Measurements for a dedicated line

@jea48

I completely understand VD on hot and neutral. Thanks, but no further explanation is needed on that. My curiosity was always with the N to EGC. That’s where I’ve been confused all along. I’ve never paid much attention to that measurement. It’s starting to click now (as you’ve raised my awareness), especially after looking at a few websites explaining what to look for. Going forward, I'll be paying closer attention to it in the future. 

Neutral-to-Earth/ground Voltage- Causes, effects, and solution

>>>With nothing on the circuit your N-E (neutral to earth or ground) should be 2V or less.<<<

I’ll be honest, I never check for this. What would be some of the causes for it?

-a less than optimum performing neutral

-leakage from the neutral to GND somewhere

@erik_squires 

>>>once current is flowing through your circuit an excessively high N-E indicates excess resistance on the neutral.<<<

OK, this is starting to make a little more sense now. A device on the circuit being tested has to be consuming *some* current for the N - E figure to take place or appear. Got it.  

@erik_squires Since I do pay a considerable amount of attention to power quality, bonding and grounding (bordering on OCD), and because of your provided link, I have now ordered this tester (mainly just for the N - E figure). I'm not sure I'm going to trust this device though after reading the 1 star reviews on Amazon. How do you think the tester obtains the N - E figure? Is the tester possibly converting ohms to volts for this test? Do you have to push a test button to see this figure, or is it always displayed?  

I received the test meter today that @erik_squires linked. Right off the bat I would say I’m impressed by its performance. One thing I look for in an AC voltmeter is how quickly it can measure and display voltage drops or variations. Even at ear splitting levels, one of my systems rarely consumes more than 1.5 amps on peaks, so I did not test it there, yet, as I doubt I’ll see much if any voltage fluctuation (10 AWG wire run about 15 feet from the load center). I did however put it on a variac, while quickly adjusting the power, simulating a huge momentary current draw on the line. The meter responded very quickly to this adjustment. All outlets that I’ve plugged it into so far are displaying 00 volts for the N-E figure. I am fortunate that I am fed directly from the step down transformer on the pole (I’m not at the end of the line) for my block. Even at that, during heavy summer cooling periods, I may see my total house voltage temporarily (for a few hours) drop about 2 volts. The meter doesn’t display tenths of volts for the L-N display, but using a reputable Fluke, the reading was only off by less than 1 volt. I would say it was easily worth the (roughly) $20 purchase price. My house voltage (on one leg I constantly monitor) typically remains at 120.7 volts 99% of the year.

Another plug in voltmeter that I really like is the Kill A Watt EZ meter. It measures a lot of things, but the voltmeter portion (which reads in tenths) is extremely accurate. 

Kill-A-Watt(Tm) Ez

Using the KAIWEETS KM117B Socket Tester (the one @erik_squires linked), I took some measurements around my home:

My pizza oven consumes 11.5 amps during operation (measured using my
Amprobe ACD-10 TRMS-PLUS meter). With the oven off, AC volts available at the outlet is 121.3 - 121.5. With the oven on, volts available at the outlet dropped to 117.8. N-E volts 00 with the oven on or off.

My microwave oven consumes 14.6 amps during operation (measured using the amprobe meter). Volts available at the outlet with the microwave off was between 121.3 - 121.5. Volts available at the outlet with the microwave on was 117.9. N-E volts 00 with the microwave on or off.

My main audio system is a 3 power amp tri-amped system. The power amps alone consume about 1.5 amps total powered on with no program material. AC volts at the outlet is 121.5 with the amps off. With the amps on, volts at the outlet are 121.0. Peak amps measured at loudest passage was 1.9 amps (or, 0.40 amps above powered up status). The feed is 15' of 10 AWG directly from the circuit breaker box. N-E volts was 00 with the amps on or off.

My furnace consumes 3.79 amps with the unit in full operation (gas burner heating, and forced air fan blowing). Volts available at the outlet with the furnace off was 121.5. Volts available with the furnace full on was 120.5. N-E volts was 00 with the furnace on or off. 

What this does prove to me is how important a dedicated run *is* for power amps, or high current consuming integrated amps or receivers. 

@erik_squires Good point Erik. I have a Panini maker which is rather light in weight, and easier to relocate vs. my pizza oven or microwave. It consumes 11.8 amps (the pizza oven consumes 11.5 amps). I plugged it into my 10 AWG main audio feed AC outlet. Volts available at the outlet at that moment was 121.8. Volts available with the Panini maker on was 119.0 (a voltage drop of -2.8 volts). N-E volts was 00.

I knew the 10 AWG feed was about 15 feet in length from the circuit breaker box to the measuring point. My other AC circuit feeds for my microwave and pizza oven I discovered are on the same 20 amp circuit as each other (good thing I never have a reason to run the pizza oven and microwave at the same time). The pizza oven and microwave are on a completely different circuit than my 10 AWG AC feed. My house was built in 1942, and the pizza oven wiring has never been updated, except with a new outlet at some point. The microwave outlet was installed at a later date, with copper wiring. The previous owners of the house had that installed. It was tied into the same circuit as the pizza oven outlet. Within the past 10 years I updated that microwave/pizza oven circuit breaker to the recent AFCI type. I’m guessing the wire run to the pizza oven outlet is around 20 feet, and the microwave outlet is 30 feet. Suffice to say there was more voltage drop at the pizza oven outlet (consuming roughly the same amount of amps as the panini maker), at -3.7 volts, than there was at my dedicated 10 AWG feed (-2.8 volts), consuming roughly the same amount of current.

Some of this was eye-opening, as I didn’t anticipate I would see that amount of voltage drop with high current demand at my 10 AWG feed, only 15 feet away from the circuit breaker box. One thing is for sure, I would not want to have any audio components on a microwave or pizza oven circuit when they would be in use.

I have a dual gang countertop outlet that has a GFCI outlet in it. It is then connected to, and protects the outlet right next to it. The microwave is across the room, and isn’t within 6 feet of the kitchen sink. When I first moved in in 2001, I inspected and replaced all of the outlets in the house. When I changed out the pizza oven outlet, the insulation on the wires was cracking, and I told myself I hope I don’t have to replace this outlet for a long time after that - so I won’t be switching that outlet to a GFCI. Since we’re discussing this, I’ll probably change out the current AFCI circuit breaker for the microwave/pizza oven circuit with the combo CAFCI/GFCI type (I have a Siemens load center). Having been an apartment maintenance guy for over 10 years, we too never installed GFCI’s for refrigerators. 

I too have whole house surge suppression (never lost anything from storm damage the entire time I lived at this location - going on 23 years now), but since I have so much money wrapped up in audio, video and AC isolation and filtering gear, I sometimes contemplate spending the money on a higher quality surge protector. 

Sine Control Technology

AC voltage, harmonic distortion and line frequency are all measurable. If there is a difference between night and day listening, and it's related to power delivery, we should be able to measure it. Personally I think some of this is psychological. Evening and night time listening hours are typically environmentally quieter, and your brain possibly adjusts to this. I've personally never measured any difference in power quality in my home environment between daytime listening and night time listening. One of my main listening rooms is down in my basement. The environment is intentionally blacked out all of the time (of course except when I light it), so that if this is a psychological thing, I can have a "night" environment whenever I want it. 

When I was a Radio Broadcast Engineer, I had a rack full of equipment in a transmitter room. This rack contained the audio processor for the FM transmitter. It created the audio signature of the FM station. The rack of equipment had a 20 plug power strip, and it was almost full. I plugged in my Fluke 43B Power analyzer, and discovered the Harmonic Distortion for this power strip was 0.0%. I kid you not. I was never able to find another AC plug that ever gave me that low of a Harmonic Distortion reading. The 3 phase power transformer for the building was on a pole right outside the door to this transmitter room.  

Are you sure you have an Equipment Grounding Conductor at the outlet?

100% most definitely; on both outlets being discussed. I can take my multimeter and read 121.6 volts across the hot and neutral (no load), and the exact same voltage is measured across hot and the EGC.

Maybe I’m not understanding you correctly, but I’m failing to comprehend why you think there should be some voltage on the EGC for these outlets (under load)? I was always under the impression that the EGC was to keep your equipment as close as possible to ground potential, and provide a safe path for ground-fault current to flow. My thinking is that if there was any voltage on the EGC, and I had in place a GFCI outlet; it would trip.

(I assume the audio branch circuit is 2 wire with ground...)

Correct.

It’s still not clicking in my brain what you’re trying to say about voltage drop across the neutral and EGC. No offense, but if I already have a low impedance EGC, why should I even care about voltage drop, or voltage difference, between the neutral and EGC?

Now draw a symbol for a voltmeter connected from the neutral on the load end of the circuit and connect the other end of the voltmeter to the EGC.

If assuming the load is plugged into one half of a typical duplex wall outlet, and consuming current; you’re saying 1) place the voltmeter on AC volts 2) one probe in the neutral on the other half of the outlet not being used by the load 3) and the other probe touching the EGC. Is that correct? If so, I’ve already tried this before you posted, and the reading is around 28 millivolts. I’ve even tried breaking the EGC connection from the load to the wall outlet, and placing my meter across it - still the same, about 28 millivolts.

BTW, thanks for taking the time to explain this to me. If neutrals were oversized (compared to the hot conductor), would I be seeing less voltage drop in some of my presented scenarios?

N-E volts 00 with the microwave on or off

Those figures were all based on using the KAIWEETS tester. I have other DMM’s which are much more accurate. Since I’m discovering my readings are now in the mV range, I won’t be using the KAIWEETS tester for these readings anymore.

You will get the same measurements on a bootleg ground.

I’ve visually inspected my outlets. They don’t have bootleg grounds...make that anywhere in my house. When I first moved in in 2001, I inspected, and changed out every outlet, along with numerous wall switches. I would have never allowed any bootleg grounds if I had encountered them. I would have recognized them even in 2001.

It looks like *this* is the ultimate outlet tester.

Ideal SureTest Circuit Analyzer

You Tube demonstration of Ideal SureTest Circuit Analyzer