Listen everyone, I have a dedicated line rated above 30 amps!, their is no issues,I have said numerous times, I have a 10/3 romex, meaning 10 awg 3 conductor dedicated line, it is the same as the captive cord on my krell 700cx, seems no one is listening to me more like it!
03-05-15: Audiolabyrinth
Audiolabyrinth, Yes from day one you said the branch circuit wiring you have is #10 awg. And yes that is the minimum size needed for a 30 amp branch circuit. If you were not using a 125V 20 amp rated receptacle your branch circuit would be code compliant. So for me in your instance the problem is the 20 amp rated receptacle. Whether you like it or not because of the 125V 20 amp rated receptacle, you are insisting on using, in the eyes of NEC code the NEMA 125V 20 amp receptacle dictates the branch circuit shall be 125V 20 amp regardless whether you used #10 awg wire or larger. Therefore per NEC Code the breaker must be a 20 amp breaker. My concern with your posts to this thread and others is when you say Krell tells customers to change out a 20 amp breaker, that is protecting a branch circuit that meets NEC code which likely may have #12 awg wire with a 15 amp duplex receptacle or a 20 amp receptacle connected to the branch wiring, to a 30 amp breaker. As for the captive power cord, my bad for being lazy and not reading through the owner manual of the Link I provided for the Krell amp above. In your particular case because at least your branch circuit wiring is #10, 30 amp rated wire, and the power cord for the Krell amp is captive that eliminates you/others from using a DIY or other non UL and or CSA Listed power cord. Why do you thing Krell chose not to use a 20 amp IEC inlet connector on the back of the Amp? At $14,000 list price for the Krell 700cx amp, Krell did the consumer an injustice, imo, by installing the 125V amperage?? type plug on the end of the 10/3 power cord. Amperage??, I could not find in any searches whether the plug is a 15 amp or 20 amp NEMA rated plug. By their specs for the amp they say it should be connected to a 20 amp circuit minimum. That would suggest the plug is a NEMA 5-20P 125V 20 amp plug. What plug did Krell install on the end of the cord? 15 amp plug?20 amp plug?Also I could not find if the Krell 700cx amp is safety tested, Listed, by any recognized independent testing laboratory like UL or CSA. Do you know if the amp is Listed? Bottom line, imo, Krell chose to use the captive 10/3 cord to stop a user from using an aftermarket power cord there by prevent the possibility of electrical fire due to the power demand the amp can place on the power cord if the amp is driven hard. And , imo, a 20 amp IEC inlet connector would never be able to handle the varying load current placed on the connector if a user was driving the amp hard. See page 22 of owner manual. Output both channels driven, 8 ohm 700 watts 4 ohms 1400 watts 2 ohms 2800 watts 8 ohms, 700W / 115Vac = 6 amps plus. 4 ohms, 1400W / 115Vac = 12.8 amps plus. 2 ohms, 2800 watts / 115Vac = 24.35 amps plus. AC mains power consumption, 6,000 watts max. @ 115V Not sure why FLA was not given. If Al is still following this thread he can do a better job of translating the info from page 22 of the owner manual than me. The plug Krell chose to use? Imo, it was chosen because the standard receptacle configuration in the USA and Canada is the NEMA 5-15R receptacle. And just guessing, imo, they used this number 4 ohms 1400 watts from their specs to justify the reason they choose the plug and not a 30 amp rated plug. . |
I can hear a fly take a wizz on the 3rd chair cellist with my fuse slugs!!
Jmcgrogan2
LOL, now that's funny. . Jim |
Using separate outlets, especially if they are on separate runs back to the breaker panel, will reduce the amount of amplifier-generated electrical noise that may couple back into the preamp. On the other hand, doing that may increase susceptibility to ground loop issues, including high frequency electrical noise as well as low frequency hum. If the connection between preamp and power amp is balanced, the likelihood of ground loop issues is considerably reduced.
02-09-15: Almarg
Hi Al, The late Al Sekela, an EE, used to post on the AA Forum why decoupling the power supplies of audio equipment by using separate dedicated circuits benefited the SQ of audio equipment. Especially decoupling digital equipment from analog equipment. As for ground loop problems I would say most ground loop problems caused from the use of multiple dedicated branch circuits is due to the choice of the materials and wiring methods used. Worst wiring method is a single conduit run with multiple single current carrying conductors with insulated safety equipment grounding conductors pulled in the same conduit. Dedicated branch circuits should never occupy the same conduit, or cable. Best branch circuit wiring practices for dedicated branch circuits is the use of 2 wire with ground NM-B cable, (Romex is a Trade Name for NM-B cable), or 2 wire with ground MC Cable with an aluminum outer armor. The construction of the two cables cancels the EMF effect from inducing a voltage onto the safety equipment grounding conducting by the magnetic fields of the hot and neutral current carrying conductor caused by the connected load. When Romex is used for moderate to long parallel runs of the cable they should be separated by at least 6 or 8 inches to prevent voltages from being induced from the hot and neutral current carrying conductors of one dedicated circuit onto others plus the safety equipment grounding conductors. Keeping them separated also, imo, helps prevent EMI/RFI noise transfer from one Romex cable to the other. Especially when one of the Romex cables will be used to power digital equipment. Jim |
Your punishment has been reduced to publicly wearing a sign stating "I have my amp and preamp on the same circuit."
Onhwy61
I have my preamp and amp plugged into the same 20 amp dedicated branch circuit and the digital on another. Works great for me. To maintain a constant voltage at the receptacle feeding the amp and preamp I chose to use 10-2 W/Grd NM-B cable branch circuit wiring. As for my responses to this thread, I was trying to justify the reasoning behind the supposedly statement made by ARC in the owners manual the OP referred to. In the case of the OP all that matters is his system sounds good to his ears plugged into a 120V 20 amp convenience outlet branch circuit. He does not have the luxury of finding out if just a new single 20 amp dedicated branch circuit would make a difference in the SQ sound of his system, let alone two. Jim |
LOL, I get a kick out of some of you guys that say a dedicated circuit is not needed to improve the sound of an audio system. It will sound its' best just plugged into a regular convenience outlet branch circuit. I guess the same could be said for OEM power cords vrs good quality after market power cords. Don't waste your money.
Mitch2,
It is not the continuous current draw of the power amp that is the problem. It is short spurts of higher than the average current pulled from the mains that can cause VD, voltage drop, on the mains that causes problems with the power supply of the amp.
A few years ago I remember reading a post by, I believe it was from Atmasphere, where he spoke on the subject. I'll look and see if I can find the post.
Jim |
Al, Thanks for finding that particular post by Atmasphere. I believe he has at least one more out there he either posted here on Agon or AA where he goes into more detail the effect a voltage sag can have on the filter caps of a power supply. The part that is the same is this statement of Ralph's,
The more insidious problem is high frequency bandwidth. The power supplies of most amplifiers have a power transformer, a set of rectifiers, and a set of filter capacitors. The rectifiers only conduct when the power transformer output is higher than that of the filter caps. So:
When the caps are fully charged the amp is able to play. As it does so, the caps are discharged until the AC line voltage waveform gets high enough again that the rectifiers in the power supply are able to conduct. Depending on the state of charge of the filter capacitors, this might only be for a few microseconds or it might be a few milliseconds. Either way, the charge is a spike which has very steep sides- and requires some bandwidth to make it happen.
Thanks Al for your example of VD, voltage drop, due to a sudden demand draw of current placed on the branch circuit wiring. Your example should be plain enough for anyone reading it. I would like you to also give an example where the branch circuit wiring is #14 gauge wire which would be a more real world example for the majority of homes in the US where guys are plugging their audio systems into a 15 amp convenience outlet circuit in the living room or a den. As for the length of the branch circuit I would be willing to bet the length of the 15 amp branch circuit wiring feeding a living room is longer than 50' on average. Of course with that said we have no way of knowing where in the entire length of the branch circuit the audio equipment is plugged into a receptacle. It could be close to the electrical panel or it could at the farthest end or somewhere in the middle. Something else, though it is impossible to calculate, is the wiring method used by the residential electrician when he made up the joints, wiring connections, feeding in and out of each convenience electrical duplex receptacle outlet wall box. Did the electrician directly connect the in and out branch circuit hot and neutral wires together respectively and extend out pigtails to feed the duplex receptacle? Or did he use the terminal side screws on the cheapo residential grade device to make the in and out connections, daisy chain, of the branch circuit? Or worse yet did he stab the wires in the back of the cheapo residential grade receptacles relying on the spring tension clip inside the receptacle to make a good electrical connection? All the above can throw a monkey wrench into the equation, especially when corrosion or an ever so slightly loose connection in the branch wiring is thrown into the mix. In this instance VD could/will be greater because the resistance through a corroded connection can change due to the load placed on it. Jim |
Al,
Thanks for your response to my previous post.
Jim |
Krell should be ashamed of themselves "IF" they are telling someone to install a 30 amp breaker when their equipment is designed and manufactured using a 15 or 20 IEC inlet connector connected to a NEMA rated 125V 15 or 20 amp plug by a cord that is designed to plug into a 15 or 20 amp NEMA rated 15 or 20 amp receptacle. Per code two or more 15 amp receptacles can be connected to a 20 amp branch circuit. To be a 20 amp branch circuit the breaker handle rating is 20 amps. Minimum wire size, #12 AWG. If a NEMA 20 amp receptacle is used the branch circuit must be a 20 amp, period. 20 amp breaker....
IF the Krell amp's FLA is 12 amps or less per UL,NEC,CSA, a NEMA rated 125V 5-15P amp plug can be used to power the amp. If over 12 amps but less than 16 amps a 20 amp NEMA rated 5-20P plug must be used.
If Krell equipment is UL listed I suggest they ask UL if it is ok to tell their consumers that for their amp to operated at its' best, as designed, the customer needs to change out the 20 amp branch circuit breaker in the electrical panel to a 30 amp. Doesn't matter if it is in violation of the local governing body electrical safety codes, UL, or NEC code.
Also it should be said in some states a company can be held libel in a court of law for injury or loss of life or property damage if it is proven they knowingly knew information they were giving to the buying consumer of their product violated electrical safety codes and or accepted electrical safety standards.
Disclaimer. I do not know if Krell is indeed telling customers to use a 30 amp breaker to feed the amp mentioned in this thread. If they are, they are grossly ignorant of accepted safety electrical standards.
. |
Jea48, Asit turns out, my krell manual for my amp says to use 20 amp single pole breaker min, they put it in their manual, that means 20am will work, really terrible, but you can get by, the 30 amp single pole allows my amp to get the correct current, does it use all 30 amps, of course not!, however, it spikes well above 20 amps, the amp never runs hot like with the 20 amp breaker, way more dynamic, bigger sound stage, it's a fit!
02-26-15: Audiolabyrinth
Audiolabyrinth, I am sure the Krell user manual says the amp should be connected to a 20 amp circuit. They did not a have a choice if they wanted to use a NEMA 5-15P or a NEMA 5-20P plug and cord to feed the amp. Just going from memory in another thread here on Agon you and I have discussed the code violation of using a 30 amp breaker on a 20 amp branch circuit that uses NEMA 5-15R, (two or more), or NEMA 5-20R receptacles connected to the branch circuit wiring. If I remember correctly you used #10awg for your branch circuit wiring instead of #12. I believe in that thread as well as this thread #10 wire I said why #10AWG wire does a better job of controlling VD, voltage drop, placed on the circuit caused by the Krell amp. As I said in the other thread the current carrying contacts as well as the other current carrying conductors in a 20 amp breaker are exactly the same as 30 amp breaker. Only the magnetic and thermal trip units settings are different. I may not be able to convince you otherwise but it is my hope that others reading this thread or other threads like it will not think it is ok to use a 30 amp breaker in place of a 20 amp breaker. If the current carrying components inside of a 30 amp breaker are larger than a 15 or 20 amp breaker then why would they sale for the same price? Square D QO 130 single pole breaker. Square D QO 120 single pole breaker. Square D QO 115 single pole breaker. If the 20 amp breaker felt warmer to the touch with the #10AWG wire connected to it the reason could be the breaker was defective. Again it had nothing to do with the differences in the size of current carrying metal components in the 20 amp verses the 30 amp breaker because there is no difference. . Jim |
Jim, you do not understand, Krell runs 30 amp braker on every krell 700cx, 750mcx amp there at the factory, BTW, I have 4 fuses, well with-in the current capability useing a 30 amp breaker, as I said befor, I am not useing all the 30 amps!,however, This amp in particular spikes well above 20 amps while in use, maybe you should call krell, then you will get all the theory as to why this works properly you want, remeber, this amp at full power is 6,000 watts!
Audiolabyrinth, IF, Krell is indeed telling customers the amp was designed to be connected to a 120V 30 amp branch circuit for use in the USA or Canada. Again IF!!! You are the one that that does not understand what Krell is actually up to. If Krell is having to connect the amp to a 120V 30 amp circuit for the amp to operate properly as designed as well as to achive the amps reported specs then Krell should be using a captive power cord and a NEMA 125V 30 amp plug on the end of the cord. The user, customer, would then be required, per NEC Code, to install a 120V 30 amp branch circuit with the correct NEMA 125V 30 amp receptacle for the Krell amp plug. Per NEC Code a 30 amp branch circuit requires #10AWG minimum wire and shall be connected to a 30 amp branch circuit breaker, period. The receptacle must be a NEMA rated 125V 30 amp receptacle, period. No exceptions. Instead Krell is apparently more interested in building a product that violates NEC code safety standards for the USA by using a 20 amp max rated IEC inlet connector on the amp where by the user can use a power cord that has a NEMA 5-15P or a NEMA 5-20P plug. Then Krell has the gull to tell a customer that bought the amp to change out the breaker at the electrical panel from a 20 amp to a 30 amp, which I believe the real reason is, because the Krell amp is nuisance tripping the 20 amp breaker on startup in rush current. So because Krell was too tight to design/incorporate a soft start circuit to limit inrush current to solve the customer's problem of the 20 amp breaker nuisance tripping they tell the customer to change out the 20 amp breaker to a 30 amp breaker. What they should be telling the customer is to change out the 20 amp breaker to a 20 amp HM, High Magnetic, breaker that has a longer delay time for startup inrush current. Problem solved. I wonder how many Krell users have followed the advice of krell? How many users who changed out the 20 amp breaker to a 30 amp on a 20 amp dedicated branch circuit that has #12AWG 20 amp rated wire? As I have pointed out earlier in this thread the current carrying contacts as well as the other current carrying metal parts of a 20 amp breaker are identical to that of a 30 amp breaker. Had an EE at Krell done his/her homework he/she would know this as well. They would also know as well a typical TM, thermal magnetic, breaker will easily pass short bursts of current of 120 amps all day long. More than enough for their amp but not enough apparently for startup inrush current. A 30 amp TM breaker will pass short bursts of 300 amps. Hell you can arc weld with 120V at 30 amps. And if the branch circuit wire is of any length and #12AWG copper once I get the #12 branch circuit wire cooking I won't have to worry about tripping the 30 amp breaker. I have looked at every article in NEC Code that pertains to the code violations and nowhere in the NEC Code book is an exception given for Krell inc. Audiolabyrinth , did you know?
NEWS from CPSC
U.S. Consumer Product Safety Commission
Office of Information and Public Affairs Washington, DC 20207
August 19, 2009
Release # 09-312
Firm's Recall Hotline: (888) 436-6055
CPSC Recall Hotline: (800) 638-2772
CPSC Media Contact: (301) 504-7908
Amplifiers Recalled by Krell Industries Recalled Due to Fire Hazard
WASHINGTON, D.C. - The U.S. Consumer Product Safety Commission, in cooperation with the firm named below, today announced a voluntary recall of the following consumer product. Consumers should stop using recalled products immediately unless otherwise instructed. Units:
Distributor: Krell Industries LLC, of Orange, Conn.
Hazard: The amplifiers were designed to operate at a temperature warm to the touch. However, a component input device can fail and cause the amplifiers to overheat, posing burn and fire hazards to consumers.
Incidents/Injuries: Krell has received 50 reports of the amplifiers overheating including reports of smoke and electrical fire. No injuries have been reported.
Description: This recall involves Krell power amplifiers with model numbers KAV-250a, KAV-250a/3, KAV-500i and KAV-1500. The amplifiers are used to provide power to a loudspeaker in a home audio playback system. The Krell logo is printed on the front of the amplifier.
Sold by: Authorized dealers and distributors of audio equipment nationwide from January 1997 through February 2001 for between $3,000 and $8,000.
Manufactured in: USA
Remedy: Consumers should immediately stop using the amplifiers, and contact Krell to schedule the free installation of replacement fuses.
Consumer Contact: For additional information contact Krell at (888) 436-6055 between 9 a.m. and 4:30 p.m. ET Monday through Friday, or visit the firm's Web site at www.krellonline.com. Consumers can also email the firm at service@krellonline.com
Krell recallI would bet that no owner of the Krell amp mentioned in this thread has anything in writing from a representative of Krell inc. stating Krell recommends changing the breaker on a 20 amp branch circuit from a 20 amp to a 30 amp breaker. All a user/customer has is a verbal conversation that is worthless in a court of law. So who is in violation of State, and local governing body safety electrical codes and electrical safety standards when a 20 amp breaker is changed out to a 30 amp breaker on a 20 amp branch circuit?
. The person/home owner that changes it out of course. I suggest you call you insurance agent and ask him/her if you are covered by your home owners insurance policy in the event of an electrical fire if it is found a 30 amp breaker is installed on a 20 amp branch circuit. Then call the governing electrical inspection department in your city and ask them about changing the 20 amp breaker to a 30 amp breaker on a 20 amp branch circuit. NEC Code 210.21 (B)(3) Receptacle Rating. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacles ratings shall conform to the values listed in table 210.21(B)(3), ........... NEC Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits. Circuit Rating ..... Receptacle Rating (Amperes) .............. (Amperes) 15 ............................ 15 20 ....................... 15 or 20 30 ............................ 30 Minimum wire size #10awg. Breaker size 30 amp. *No exception given for Krell Inc. Circuit Breaker MythsSiemens BreakersElectrical-forensics. |
See page #5 Full Power Balanced
X Series Power Amplifiers
AC POWER GUIDELINES
The Full Power Balanced 300cx and 350Mcx
amplifiers need to be operated from a dedicated
AC power line rated at a minimum of 15
amps. The Full Power Balanced 700cx,
750Mcx, 400cx, and 450Mcx amplifiers need to
be operated from a dedicated AC power line
rated at a minimum of 20 amps.
Please contact your authorized Krell dealer, distributor,
or Krell before using any devices
designed to alter or stabilize the AC power for
Full Power Balanced amplifiers.
Note the word [minimum] used for the "750Mcx, 400cx, and 450Mcx amplifiers need to be operated from a dedicated AC power line rated at a minimum of 20 amps." If the equipment is manufactured for use in the USA with the intent of using a power cord with a NEMA 5-20P 125V 20 amp plug then the max branch circuit ampacity rating is 20 amps. Period! The minimum branch circuit ampacity rating because of the NEMA 5-20P plug is 20 amps. Period! Minimum wire size #12AWG copper. Branch circuit breaker size, 20 amp. Period! Receptacle, if the Krell power cord plug is a NEMA 5-20P plug then a NEMA 5-20R 125V 20 amp receptacle for the plug to fit it is required. All the above are NEC Code minimum electrical safety standard requirements. Krell can spec #10 AWG copper wire, which I would recommend. For long branch circuit runs maybe even #8 AWG Cu. They can spec an HM, High Magnetic, 20 amp breaker must be used to help prevent nuisance breaker tripping. They should spec that only power cords that has a NEMA 5-20P plug can be used with a minimum cord conductor wire size of #10AWG. They can spec only a NEMA 5-20R 125V 20 amp heavy duty commercial/industrial rated receptacle be used. The bigger wire and heavy duty receptacle will help reduce voltage sag on the branch circuit wiring, receptacle contacts to plug blades, and power cord wire right up to that 20 amp IEC inlet connector mounted on the back of the unit caused by the Krell amp's dynamic power connected load. They cannot spec a 30 amp circuit breaker be used on a 20 amp branch though. You will notice in the owner manual a 30 amp branch circuit was not mentioned. Everybody reading this thread by now should know the reason why. . |
Edit for previous first post dated 03-03-15: Jea48 NEC Code 210.21 (B)(3) Receptacle Rating. Where connected to a branch circuit supplying two or more receptacles or outlets, receptacles ratings shall conform to the values listed in table 210.21(B)(3), ........... NEC Table 210.21(B)(3) Receptacle Ratings for Various Size Circuits. Circuit Rating ..... Receptacle Rating (Amperes) .............. (Amperes) 15 ............................ 15 20 ....................... 15 or 20 30 ............................ 30 Minimum wire size #10awg. Breaker size 30 amp. *No exception given for Krell Inc. >>>>>>>>>>>>>>>>>>>>>>> Strike, Minimum wire size #10awg. Breaker size 30 amp. and replace with, The branch circuit breaker size determines the size of the branch circuit. If the branch circuit breaker is 30 amp then the minimum wire size must be #10 AWG. It can be bigger but it cannot not smaller. The receptacle must be a NEMA 125V 30 amp rated receptacle. It cannot be bigger, it cannot be smaller, it can only be a NEMA 30 amp rated receptacle. . |
Thanks Al for your response to my post above.
.
Jim |
Audiolabyrinth, Krell chose to use a 125V 15 amp plug on the unit because the 125V 15 amp duplex is the standard wall receptacle found in dwelling units, homes, in the US and Canada. Krell did choose to use the 15 amp plug for economic reasons. Not because of the price of the 15 amp plug verses a 20 amp or 30 amp plug, but because how many people in the US or Canada have NEMA 5-20R 125V 20 amp duplex receptacles in their living room, family room, parlors, libraries, dens, bedrooms, or recreation rooms? They have 15 amp duplex receptacles because NEC Code says the minimum wire size that can be used on a 15 amp branch supplying power to a 15 amp branch circuit is #14 awg wire connected to a 15 amp breaker. You will find in most cases, at least in the US, residential dwelling units are wired to NEC Code bare minimum standards. But wait, Krell says the minimum circuit ampacity required for the Krell 700cx amp is 20 amps. Does your Krell 700cx amp have a 20 amp plug on the end of the cord? No, not by what you have said in your last post, it has a 15 amp plug. So why didn't Krell at least install a 20 amp plug on the end of the cord? Well that's easy, any fool knows a 20 amp plug will not fit, plug, into a 15 amp receptacle. Of course if Krell had installed a 20 amp plug on the end of the cord that would have required a 20 amp receptacle with #12 awg cu wire minimum, connected to a 20 amp breaker. Only a 20 amp breaker! I asked you in my last response to you if the Krell 700cx amp is UL and or CSA Listed. My guess it is not! As for what Chris Vanhause of Vh-Audio may have told you, I only have your side of the conversation. I would hope Chris is not telling customers it is ok to connect the furutech FI-50 Rhodium plug and Furutech receptacle to a 30 amp circuit.I suggest the manufacture of the plug and receptacle should be contacted and ask them what they have to say. IF, Furutech plugs and receptacles are UL and or CSA Listed connecting them to a branch circuit voltage or amperage circuit other than what the plug and receptacle is designed and manufactured for voids the UL Listing of the device. I would bet it also voids the manufacture warranty. As for differences found between a 125V 15 or 20 amp plug and receptacle and that of a 30 amp receptacle I suggest you go to the local electrical supply house or Home Depot store in your area and compare them to one another. What you will find is the 30 amp plug and receptacle contacts are about 50% bigger. Yes more surface area as well as more meat on the bone. After all the devices are designed and manufactured to handle 50% more load than the 15 or 20 amp device. The spacing between the contacts apart from one another is greater on the 30 amp than the 15 or 20 device. Here is some more info on the Krell 700cx amp. Audio Video Revolution, review. The Stereo Times, review. I found this thread on AA. Two 4KVA toroidal transformer in the Krell 700CX? When connected to a 30 amp branch circuit breaker the only thing that holds that puppy back is the breaker on the back panel of the unit. I wonder if it is a 30 amp? I doubt it. Audiolabyrinth, is it true the amp has two 4KVA power transformer? Do you know the ampere rating of the circuit breaker mounded in the back rear panel of the amp? 15 amp? 20 amp? Do you know if it is a magnetic trip breaker only? Another Agon thread.
09-13-10: Mclsound
thanks guys
Seems like most are using a 20amp rec. with 10awg wire and 30amp breaker.
. . I will leave you with this.
If a circuit breaker is over loaded to a value of 135% it rated current, it must trip within one hour.
If a circuit breaker is over loaded to a value of 200% it rated current, it must trip within two minutes.
Electrical ForensicsSo a 20 amp receptacle installed on a 30 amp breaker could be 135% overloaded for up to an hour before it is supposed to trip open. 30 amps X 135% = 40.5 amps Has to trip open if overloaded by 200% in 2 minute. 30 amps X 200% = 60 amps Compared to, 20 amp breaker X 135% = 27 amps. 20 amp breaker X 200% = 40 amps . Jim |
Edit to my last post. Do you know the ampere rating of the circuit breaker mounded in the back rear panel of the amp? 15 amp? 20 amp? Do you know if it is a magnetic trip breaker only?
Should read, Do you know the ampere rating of the circuit breaker mounted in the back rear panel of the amp? . |
Also the stock Krell cord indeed has a 15 amp male plug, and probably for the reason you mentioned here earlier, but he feels it is good for 35 amps. It is a heavy sonofabitch.
03-07-15: Ct0517
LOL, he feels it is good for 35 amps? The manufacture of the plug rated the plug for a continuous connected load of 12 amps as per NEC Code, NEMA standards, as well as UL testing for a NEMA 5-15P 125V 15 amp plug. In other words the 15 amp plug can only be used on equipment that has an FLA of 12 amps or less. The 15 amp plug's blades and ground pin are the same size as that found on a 20 amp plug. The difference between the 15 amp plug and the 20 amp plug is on the 20 amp plug the neutral blade is turned 90 degrees with respect to the hot blade. In the electrical trade that is called making the device idiot proof. A 20 amp plug cannot be plugged into a 15 amp receptacle that could be connected to a 15 amp branch circuit, that is protected by a 15 amp breaker, in most cases the branch circuit wiring is #14 awg rated for 15 amps max. Do you think Krell is so stupid they do not know that? Hey, but the tech says the plug is good for 35 amps. I guess he would say the #14 cu wire is good for 35 amps as well. Forget about the plug, think about the non knowing consumer that bought the amp. If the plug on the amp plugs into the wall receptacle in his living room that's all that matters. Think the guy knows the branch circuit is only a 15 amp? All the consumer knows is that Krell knows what they are doing and the plug on the end of the cord plugged into the receptacle. Then his problems start. Who does he call first? Probably the dealer that sold him the amp. Just change the 15 amp breaker to a 20 amp breaker. Problem solved. Hell, the tech said the plug is good for 35 amps. Change it out to a 30 amp breaker! Whats a few more connected load amps among friends.
I brought up what was discussed here about putting a 30 amp breaker in the fuse panel on a 20 amp line.
He laughed, called it counter productive and for what ? He does not support it, for some of reasons stated here and used some words that I can't publish here. He then rimmed me and told me to stop reading internet banter. I told him it was cabin fever but that today is a nice day so I will go out and play.
If he does not support it why is Krell telling owners of the amp to do it? He then rimmed me and told me to stop reading internet banter.
Oh, I just bet he did! Maybe if he read what is posted on audio forums he might learn something. He may also learn non-qualified people are doing what he/Krell suggests and or maybe worse. . Like I said early on in this thread Krell should be ashamed of themselves. I would guess the tech is not a state licensed electrician and it is obvious he does not know what the hell he is talking about. His expertise stops where the power cord exits the equipment. IF the amp has a 20 amp breaker on the back panel then the 125V plug should be a 20 amp plug. Krell should stop telling dealers as well as consumers that a 15 amp plug is good for 35 amps. The plug is not the issue. The issue is what the plug can be plugged into. If krell thought the 15 amp plug was plenty big, there in the FLA of the equipment does not exceed 12 amps, then they should have installed a 15 amp circuit breaker on the rear panel of the amp instead of a 20. Do you know why they didn't? NEC Code
Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle. |
Mrvordo, Did you tell Audiolabyrinth it was alright to install a NEMA 5-20R receptacle 125V 20 amp rated receptacle on a 30 amp branch so he could then plug in the NEMA 5-15P 125V 15 amp plug that is connected to a power cord that feeds the Krell 700W @8 ohm, 1400W @4 ohm, 2800W @ 2 ohm, with an up to 6000 Watt power consumption rating per Krell specs of the amp?
03-04-15: Audiolabyrinth
Jea48, one of these audiogon members that has e-mailed me for months about the 30 amp breaker is MRvordo, you can consult with him, maybe bring him to this thread, he uses the 30 amp breaker on his krell 750mcx mono amps, I believe a 30 amp breaker for each?, any way, every aspect of what he said this will do for my amp was spot on correct, he is one among many others that have done this with no issues.
Audiolabyrinth
03-08-15: Mrvordo
I have come late to this party, and I didn't read every single post, so forgive me if I missed something important to the discussion.
First off, Krell IS NOT recommending that you simply replace your 15A breaker with a 30A breaker. What they do recommend is that in order to get the best out of the amp, use a 30A breaker with the APPROPRIATE wiring on a DEDICATED line. Appropriate wiring would, of course, include the appropriate outlet and plug.
Mrvordo
Really? Curious why didn't Krell just install a 30 amp plug on the power cord to begin with? . Highlights.....
02-13-15: Audiolabyrinth
Mitch2,That is funny!, my amp got way to hot on just a single pole 20 amp breaker, krell told me that my amp was designed to run on single pole 30 amp breaker, guess what, I did what krell told me to do, my amp has incredible dynamic's, bigger sound stage and transparency, and now for the kicker, the amp never run's hot and operates smoother, my krell kick's a 20 amp in the Axx!
Audiolabyrinth
02-28-15: Audiolabyrinth
Jea48, I do not understand why you would make humor of the truth, I had numerous others with the Krell 750MCX mono block's and the stereo Krell 700cx say the same thing, they encouraged me to use the 30 amp breaker as did krell them selfs,no one knows it all, we all learn from each other, I did not believe that the 30 amp breaker would do any thing either, but when I got 20hrs of break-in on the breaker, it turned out to be the best cheap tweak ever I have done in my life time, the benefit's was worth thousand's of dollar's to me!
Audiolabyrinth
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03-03-15: Audiolabyrinth
Jim, you do not understand, Krell runs 30 amp braker on every krell 700cx, 750mcx amp there at the factory, BTW, I have 4 fuses, well with-in the current capability useing a 30 amp breaker, as I said befor, I am not useing all the 30 amps!,however, This amp in particular spikes well above 20 amps while in use, maybe you should call krell, then you will get all the theory as to why this works properly you want, remeber, this amp at full power is 6,000 watts!
Audiolabyrinth
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03-04-15: Audiolabyrinth
Jea48, one of these audiogon members that has e-mailed me for months about the 30 amp breaker is MRvordo, you can consult with him, maybe bring him to this thread, he uses the 30 amp breaker on his krell 750mcx mono amps, I believe a 30 amp breaker for each?, any way, every aspect of what he said this will do for my amp was spot on correct, he is one among many others that have done this with no issues.
Audiolabyrinth
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03-05-15: Audiolabyrinth
thankyou ct0517, it is patrick bresnahan that asked the technician's and R&D design team about the 30 amp breaker, this was NOT my idea at all, it was numerous other big krell amp owner's and krell that made this sugestion to me,however, Patrick is correct about the male wall plug, I have no issues at all, but I also said, I will be getting a high performance male wall plug for sound, Not any thing else, if I decide I really want one, currently, I do not, cheers.
Audiolabyrinth (Threads | Answers | This Thread)
03-06-15: Audiolabyrinth
Jea48, Hi, believe it or not, I have $11,500.00 into my amp!, it is totally new out side nearly everything inside, however, I was shocked myself, I have no idea Jim as to why Krell used a inter power 15 amp wall plug on this captive power cord!, unless they were tring to save money,LOL!, the inter power I have is brass, ok sound for what it is, but you can see as to why going to a high end wall plug like the furutech FI-50 Rhodium that is overly built 20 amp would be a good idea, Jim, I talked to chris vanhause of vh-audio, he sells the 30 amp wall plug version of the FI-50, his words- why would you buy this?, the 30 amp only has a little bigger contact surface area inside, the side ways blade is for child safty or people that would try to plug this type of wall plug to a normal fitted wall outlet, their is NO difference in each one for sound or power handling., end quote, chris also told me he does not list the 30 amp wall plug version on his site, no need, the version he sales is cheaper and can handle a load that I have here for sure, that said, I believe krell also used the inter power 15 amp plug on my captive power cord because this will not make any difference useing a 30 amp circuit, I know you dont believe that Jim, however, I have no issues!, the wall plug does not in any way change temperture driving the amp hard, it stays cold all the time jim, like I said, I am only conterplating on this furutech FI-50M for sound purposses only because I have the matching wpo's-wall power outlet's, thankyou jim, I am reading into what you are posting, I do not disagree with you, but I am saying I have NO issues here with what I have set-up, I constanly check, cheers.
Audiolabyrinth
quote "I believe krell also used the inter power 15 amp plug on my captive power cord because this will not make any difference useing a 30 amp circuit," . . Again for the umpteenth time there is no difference in the contacts or associated current carrying circuit parts of a 20 amp breaker or a 30 amp breaker! ONLY the TM, thermal and magnetic, trip setting are different. Any differences possibly heard could only be because of the contact seating of the contacts in the breaker or possibly the tension contact of the breaker to the bus tie of the bus of the electrical panel. Note the breaker connecting mechanism is made of exactly the same material for both the 20 amp breaker and the 30 amp breaker for that manufacture, model and style number. TRY A DIFFERENT 20 AMP BREAKER! Then listen again for any difference. IF you hear a difference it is all in your head! For those of you that are hell bent on using a 30 amp circuit connected to a 20 amp receptacle in violation of all electrical safety codes why are you limiting yourselves to using a 30 amp breaker? Why not stick a 60 amp breaker in the panel in place of the 30. Hell, better yet, eliminate the bottle neck breaker all together and tie the hot conductor for the branch circuit directly to the HOT bus on the panel. And for even better performance of the Krell amp eliminate all fusing inside the amp. Talk about a bottle neck, can you imagine all the electrons being forced to get into single file to pass through that small little wire inside the fuse. Let them run free.... . |
03-09-15: Ct0517
03-06-15: Jea48
Edit to my last post.
Do you know the ampere rating of the circuit breaker mounded in the back rear panel of the amp? 15 amp? 20 amp? Do you know if it is a magnetic trip breaker only?
@Jea48
I received info from Patrick Bresnahan at Krell that these are 50 amp breakers.
I provided some info in my previous post about how it works.
Cheers
Ct0517
Ct0517, Thank you for taking the time and finding out the rating of the breaker. 50 amp breaker.... 'IF' we are to assume the breaker handle rating of the breaker is 50 amps that could explain the power consumption max rating given in the Krell owner manual. 6000 max. watts / 115Vac = 52.17 amps. IF , The 700CX amp has two 4kva power transformers. 4000VA, watts, / 115 = 34.8 FLA primary amps, secondary fully loaded for each transformer. (For purposes of transformer rating only). Note, this assumes there is not any other current limiting fusing after the load side of the rear panel 50 amp main breaker of the Krell amp for each power transformer primary winding. Secondary fuse protection could/would limit the amount of power that could be drawn from each power transformer as well. The 50 amp rear panel breaker limits the max FLA combined total possible connected load of the two transformers by a little over 80%. 34.8 X 2 = 69.6 X 80% = 55.68. So what else limits the mains 115Vac power for the 700CX amp? The branch circuit breaker in the electrical panel. Though remember the branch circuit is meant to protect the branch circuit wiring not what is connected to it at the wall receptacle. It is the manufacture's responsibility to select the proper NEMA plug for the FLA load for his equipment. If he say the equipment should be connected to a 20 amp circuit then his equipment must not draw more than 16 amps FLA. The plug on the end of the cord shall be a NEMA rated 125V 20 amp plug. PERIOD! So far I have resisted giving any, "what if", happens in this thread concerning the Krell 700CX. So if the branch circuit feeding the amp is 30 amps, what if there is a ground fault event anywhere in the 120Vac power wiring inside the amp, including the hot side fed of a primary winding of one of the 4kva transformers, to the safety equipment grounded metal chassis of the amp? Will the ground contacts of the plug/wall receptacle combo be able to handle the ground fault current that will travel back to the source, the electrical panel? If the receptacle and plug are NEMA 30 amp rated and UL and or CSA Listed then yes the equipment ground contacts of the plug and receptacle will be able to handle the possibly extremely high current the 30 amp breaker can supply until it reacts to the ground fault load current placed on it and hopefully trips open and breaks the ground fault circuit. If it's a NEMA 5-15P plug/5-20R receptacle connection who knows? Not the manufacture of the devices. Not UL or CSA. And I would be willing to bet Krell doesn't know either. . |
Edit. Though remember the branch circuit is meant to protect the branch circuit wiring not what is connected to it at the wall receptacle.
Should read, Though remember the branch circuit breaker is meant to protect the branch circuit wiring not what is connected to it at the wall receptacle. . |
Jea and Jmcgrogan, I thought you two already knew that you can't teach a pig to sing, and I'm certainly not going to try.
03-09-15: Mrvordo
I never said that. Pig singing.. |
Edit post, 03-09-15: Jea48.
So if the branch circuit feeding the amp is 30 amps, what if there is a ground fault event anywhere in the 120Vac power wiring inside the amp, including the hot side fed of a primary winding of one of the 4kva transformers, to the safety equipment grounded metal chassis of the amp? Will the ground contacts of the plug/wall receptacle combo be able to handle the ground fault current that will travel back to the source, the electrical panel? If the receptacle and plug are NEMA 30 amp rated and UL and or CSA Listed then yes the equipment ground contacts of the plug and receptacle will be able to handle the possibly extremely high current the 30 amp breaker can supply until it reacts to the ground fault load current placed on it and hopefully trips open and breaks the ground fault circuit.
If it's a NEMA 5-15P plug/5-20R receptacle connection who knows? Not the manufacture of the devices. Not UL or CSA.
And I would be willing to bet Krell doesn't know either.
Quote "Will the ground contacts of the plug/wall receptacle combo be able to handle the ground fault current that will travel back to the source, the electrical panel?" It should have been obvious but I should have included the plug/wall receptacle Hot contact connection as the Hot brach circuit conductor that is connected to the Hot contact of the receptacle is feeding the high current, caused by the ground fault event, back to the source, the electrical panel, through the safety equipment grounding conductor. "Houston, we have ignition!" Also in case it was not clear my load calculations, in the post, were for possible FLA full load of the two 4 KVA power transformers. I have no idea what the actuals loads could be. If Al couldn't figure them out from the Krell specs given, I assure you I can't. I did try to find a wiring diagram for the amp on the net without any luck. 03-09-15: Ct0517 post reminded me again from a previous post of his the rear panel 50 amp breaker has a pair of wires for hard wire remote control of the breaker. Just a guess, and that's all it is, the 50 amp breaker has a shunt trip solenoid that when energized will mechanically trip the breaker open. The shunt trip circuit could be controlled through relay contacts of relays that are controlled from each channel of the amp. This could be part of overload protection for the two power amplifiers of the amp. A wiring diagram of the amp's overcurrent protection would be nice. For those interested, a look inside the Krell 700CXIt's just a shame Krell did not put a 30 plug on the end of the power cord to began with .The power of electricity. |
