I've recently acquired a pre-owned T+A PA 3100 HV integrated and this is my first exposure to a 20 amp power cable. The supplied cable has what I think is a C19 IEC connector (20 A) on the amp end, but the connector on the wall side has parallel hot and neutral blades as opposed to the 20 amp T blades. Is that end really rated at 20A?
I have a dedicated 110V 20 amp circuit with 20 A receptacles, but is about 10 ft from my equipment. I am currently plugging the amp's supplied cable into an Oyaide OCB-1 SX V2 power conditioner which is plugged into the 20A wall receptical. The wall plug on the Oyaide appears to be a 15A plug and the 4 distributed receptacles are not 20A and I assume they are rated for 15A. Is this dangerous to have this 15A section between wall and amp?
Would I be better off, or safer to find a 20A extension cable so I could plug the amp directly into the wall? I've recently started building my own PCs and could make a 10 ft one with C19 on one end and 20A wall plug on the wall side ( ouch for wire cost for 10ft). I know that its unlikely the amp will ever draw more than 15A.
@mintakax The only benefit you will get from plugging it into a 20A circuit is that likely that circuit would be a dedicated line, so it would be isolated from other noisy electronics on the same circuit.
I am an authorized T+A dealer, and I can tell you that the most powerful fuse in the unit is 10A, so it for sure never draws more than 15A. If anything, it actually only uses less than 5A continuously.
Actually for both my own T+A A 3000 HV and PS 3000 HV, I replaced the 20A IEC with 15A ones. This opened up my ability to choose from many more available power cables with 15A connectors.
And in case you ask, no, a 20A cable does not deliver more current than a 15A cable if it is not needed. Quality high current cables (e.g. 10AWG conductors) can do wonders to help that amp sing.
@mintakaxAre you the individual who purchased a PA 3100 HV locally in CO? If so, I work with the previous owner from time to time as well.
FWIW, the optional PS 3000 HV power supply should be on your consideration set for down the road. It significantly improves the performance of the unit in terms of coherence, soundstaging, and control.
Check the fuse rating on the back of your amp. It’s probably a lot less than 20A. :) I don’t have access to the manual but I saw an image which specified 1500W on the back. This should be around 12 Amps. A 15A circuit is generally rated to 1800W, a 20A circuit for 2400, so definitely a good thing you are using a 20A circuit!
Any decent conditioner should also have a built in breaker, so in the unlikely event you overload it the breaker should trip quickly.
Generally speaking, there’s not a lot of difference between a 20A outlet and 15A outlet. They both have to be built for 20A due to the NEC allowing a mix of 20A and 15A plugs on a 20A circuit.
That’s not to say the wiring in the wall doesn’t need to match the breaker in your panel, it absolutely does. :)
The thing to consider for the long term is how much of those 1500 watts do you actually use while listening? The more of that you use the more likely you can make your line sag. To find out use a voltage meter like this one. Leave it plugged in and pay attention as much to the N-E as the overall voltage. This will also help you understand how much voltage variance you have due to seasonal/major appliance use and how much is due to your gear.
@mintakaxto start with, a cable with a 20 amp IEC and 15 amp plug is not conforming to north american electrical codes and should not be used.
Granted, it will work, but if there is ever a related shock or fire event, your insurance would probably void the claim.
Granted, the amp will probably never draw close to 20 amps continuous, but transient spikes may exceed 15 amps, which may explain why the amp has a 20 amp IEC socket.
To keep the "codes people" happy...
Put a 20 amp plug on the cable for the amp
Plug the amp into the wall.
If the cable is not long enough make a 20 amp extension cord.
Use the ocb-1 for other components and plug it into the same wall outlet
Re: the wall outlet: replace the outlet with a 20 amp hospital MRI grade outlet. It will grip the plugs very tightly and improve overall performance.
@ditusawhile you can clearly buy such a cable, for a receptacle the code states...
A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.
So my interpretation is that the plug and socket on a cable should be of the same rating, because the cable is just an extension of that branch circuit.
I think it is one of those grey areas that will only be judged in the event of a catastrophic failure unfortunately.
A single receptacle installed on an individual branch circuit shall have an ampere rating not less than that of the branch circuit.
True, not less than. The single receptacleinstalled on an individual branch circuit can have an ampere rating greater than the ampacity rating of the branch circuit. Therein a single NEMA 5-20R (20 amp) receptacle can be installed on a 15 amp branch circuit.
@ditusa- thanks for that info. Its interesting that UL allows this practice. Goes against everything I was taught in college in the UK, but that was some 50 years ago
So I guess it boils down to personal preference as to how safe a person would like to feel using a power cable of this design.
Personally, I would err on the side of caution and change the plug to a 20 amp model.
Check the fuse rating on the back of your amp. It’s probably a lot less than 20A. :) I don’t have access to the manual but I saw an image which specified 1500W on the back. This should be around 12 Amps. A 15A circuit is generally rated to 1800W, a 20A circuit for 2400, so definitely a good thing you are using a 20A circuit!
No fuse on the back of the amp. Fuses are inside. Accessed from removing the bottom cover of the amplifier. I couldn’t find anywhere on the Net what the ampere rating is for the fuse(s).
I don’t have access to the manual but I saw an image which specified 1500W on the back. This should be around 12 Amps.
.
This should be around 12 Amps.
Agree. 1500W/120Vac (nominal) = 12.5A
On HiFi Engine Web Site you can access the owner’s manual. Listed in the specs it says AC power consumption max 1500 watts. Not sure exactly how the 1500W max power consumption number is applied. Max continuous watts???. I don’t think so. There is only one power transformer. 1000Va, 1KVa.
Available short term overload of the 1000Va transformer??? Just a guess, there is a rated overload percentage. (service factor). Look at the specs for head room for 8 ohm and 4 ohm max power ratings.
The amplifier has to have a soft start circuit, imo, to limit inrush current. If not the electrical panel circuit breaker would see a dead short on turn-on of the amplifier and trip on its short circuit protection.
So back to the overload protection AC line fuse in the amplifier. 10A, I assume slow blow.
IF the FLA is 8.3A the fuse was sized at a little over 120% of 8.3A. (Good chance the circuit designer of the amplifier sized the power transformer at 80% of the of the FLA of the amplifier. That leaves 20% head room for playing/listening to music with high dynamic music passages.)
It would be nice if a reviewer took the time to measure the AC line current at power output clipping.
From the owner’s manual specs:
Output Power* (Peak)
8 ohm 380 W
4 ohm700 W
Peak is not max continuous output power.
Just for a rough AC mains current draw calculation using 4 ohm 700W.
@blisshifi-- Hi, yes I am that person. Nice to know that you worked with Michael. I will put the PS 3000 on my "down the road list". Next stop for me is a speaker upgrade :).
I ended up buying a 10ft, 10AWG cable with a 20A C19 female and 15A male to go right to the wall plug. The 10ft definitely adds some cost. I could have done a 20A male connector but I thought it might reduce the resale prospects if I ever wanted to sell it. At any rate that could easily be changed.
It refers to the ability of an amplifier to deliver a greater amount of power on brief musical peaks than the amount of power it is rated to deliver continuously.
That can be good in the sense that the peak power levels required by a lot of music can be vastly higher than the average levels that are required. Classical symphonic music is one of the most extreme examples of that.
However, high dynamic headroom can also be an indication that the amplifier's power supply and/or its thermal design are "weak," because it indicates that the amplifier cannot sustain its maximum power capability for very long.
2x200W amp might take from mains close to 1kW during peaks. The problem is that peak supply current won’t be expected 8A, but rather close to 40A. It is because current is drawn only for very short time (millisecond pulse) at the peak of full wave rectified sinewave. It applies to most of LPS. Power delivered with such short pulses not only creates larger voltage drops in house wiring, but also heat-up amp’s power transformer, that has to be oversized (higher copper losses and higher core losses for eddy currents and hysteresis).
It's not just the ampere rating size of the AC power fuse used in a power amp that determines the wire size needed for branch circuit wiring and the size of the wire used in a power cord.
The power supply of a power amplifier likes/needs a steady state AC mains voltage.
I read the recent thread you participated in (AC Power in misc-audio), lots of good info in that thread. I may end up putting in a Furman P-2400 at some point.
I read the recent thread you participated in (AC Power in misc-audio), lots of good info in that thread. I may end up putting in a Furman P-2400 at some point.
I don’t know enough about P-2400 to recommend it one way or the other. Especially if you would be plugging the T+A PA 3100 HV integrated amp into it.
The T+A PA 3100 HV integrated amp has a very robust power supply.
"1000VA toroidal transformer with 120,000µF of filter capacitance."
Jmho the amp should be plugged directly into the 20A dedicated branch circuit wall outlet.
Available power at the wall outlet for this,
for very short time (millisecond pulse) at the peak of full wave rectified sinewave.
is pretty much unrestricted. A 20A circuit will easily pass very short time (millisecond pulse) s many times the 20 amp breaker’s handle rating. (Same for the 10A slow blow fuse in the PA 3100 amp.
Limiting factor? VD, (Voltage Drop) on the AC mains caused by the load of the power supply on the branch circuit wiring. Therein the connected load of the amplifier playing high dynamic music at a high volume level. (Not a steady continuous load... This load, "very short time (millisecond pulse) at the peak of full wave rectified sinewave."
What determines VD on the branch circuit wiring? Connected load in amperes, length of the branch circuit wiring X two, and wire gauge size. (Remember the 20A breaker will pass short pules of current well over its’ handle rating, all day long.)
Question.
What AWG wire size did the electrician install for the 20A dedicated branch circuit? #12AWG? #10AWG?
Guesstimate length of the wiring from the electrical panel to the wall receptacle outlet? Try to include up, down, over and around lengths to the total length of the branch circuit wiring.
T+A specifies the PA 3100 HV’s maximum continuous power as 300W into 8 ohms (24.8dBW) and 500W into 4 ohms (24.0dBW). With both channels driven and using our definition of clipping, which is when the output’s percentage of THD+noise reaches 1%, fig.4 indicates that the amplifier clipped at 318Wpc into 8 ohms (25.0dBW). The T+A amplifier also exceeded its specified power into 4 ohms, clipping at 525Wpc (24.2dBW), again with both channels driven (fig.5).
(I don’t hold the AC wall voltage constant for these tests. With the amplifier idling, it was 121.6V; with the amplifier clipping into 4 ohms, the AC supply voltage had dropped to 117.9V.)
Just a guess measurement were taken with an RMS multimeter.
What was the base line for the AC VD measurements? What did the current, in amperes, measure on the branch circuit wiring?
What determines VD on the branch circuit wiring? Connected load in amperes, length of the branch circuit wiring X two, and wire gauge size.
It would be nice if a reviewer took the time to measure the AC line current at power output clipping.
From the owner’s manual specs:
Output Power* (Peak)
8 ohm 380 W
4 ohm700 W
Peak is not max continuous output power.
Just for a rough AC mains current draw calculation using 4 ohm 700W.
700W / 120V = 5.8A + unknown loses.
700W / 120V = 5.8A + unknown loses would be for one channel.
Both channels driven peak watts would be 1400W / 120 = 11.67A + loses.
Problem is my above calculations are flawed and do not express what is actually happening on the AC mains branch circuit wiring.
It doesn’t account for this.
2x200W amp might take from mains close to 1kW during peaks. The problem is that peak supply current won’t be expected 8A, but rather close to 40A. It is because current is drawn only for very short time (millisecond pulse) at the peak of full wave rectified sinewave.
I’m not sure what type of current measuring test equipment would be used to measure for dynamic short spurts of current draw on the AC mains branch circuit wiring caused by high dynamic music passages for music being played. A regular Clamp Amp meter will not catch, register, the current draw event fast enough, imo. Unless several peaks were close together. ??? Not even sure then. Maybe an Oscilloscope?
@kijanki might be able to answer the question. And, more than likely, rephrase it better, what I’m trying to say.
Thanks! I believe the wire was 12AWG and the run is roughly 60ft. Most of the advice I've received has been to plug the amp into the 20A wall outlet.
Hindsight is 2020. I wish I had asked you earlier in the thread about the AWG wire size of the branch circuit wiring. Especially before you had, bought, a 10ft 10AWG power cord made.
60ft 12ga branch circuit wiring feeding the PA 3100 HV integrated amp may be sounding fine, good, to your ears. That is all that really matters.
(#12AWG is the bare minimum required for a 20A branch circuit.)
IF you ever decide to have another 120V 20A dedicated branch circuit installed for a 60ft - 70ft run, I would recommend using solid core #10AWG wire.
My first preference is 10/2 Solid core MC (Metal Clad) aluminum armored cable. Second choice is 10/2 NM sheathed Cable. (Romex, Trade Name).
FYI, the circuit breaker will be 20A. The circuit breaker determines the size, amperage rating, of the branch circuit. Therein even if the branch circuit wiring is #10AWG the circuit breaker cannot be bigger than 20A. The connected 20A duplex wall outlet is Listed for use on a 20A circuit only. Cannot be installed on a 30A circuit.
Are you saying the 10AWG power cord could have been 12 AWG and would have been less expensive?
No, not saying that at all.
My thinking was, If I had ask about the size of the wiring of the existing 20A dedicated branch circuit, before you bought the 10ft power cord, and I found it was #12awg 60ft long, I would have recommended you have a new 20A dedicated branch circuit installed using #10AWG solid wire installed closer to your audio system. Forget buying a 10ft power cord and use the money instead toward the cost of a new 20A dedicated branch circuit for the PA 3100 HV integrated amp.
You could have hired the electrician to extend the existing 20A dedicated branch circuit closer to your audio system equipment for any digital equipment you have. Including any SMPS equipment you have.
So you have a dedicated 20A outlet. Your amp is one of the very few that needs a 20A supply. Yet you wonder if it is ok to use a 15 amp circuit. Maybe it is. but why not just do it right. Replace the cord on your amp with a cord long enough to plug into the 20A outlet.
Always avoid extension cords, even if they have a long cool sounding name like "Oyaide OCB-1 SX V2".
Apologies if I gave the impression that I was wondering if it was OK to use a 15A circuit. I was never going to do that. I was wondering about the 15A male plug on the supplied PC and the 15A male plug on the power conditioner. At any rate if you read back a couple of post you will see that I bought a 10ft 10AWG PC to plug directly into the 20A receptacle.
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