I hope you don't go through all that trouble just to find you've overlooked a shoddy crimp sleeve connection in the vanity light.I did. It keeps getting better as I get to the breaker, but nothing extreme. Going to get rid of the backstabbing this weekend in ALL the outlets in the house
This doesn't make sense to me. 6 outlets before the hairdryer and only 25' of wire? That doesn't seem possible.After all this I run a hairdryer in the house at the outlets while checking voltage. I find a circuit that goes from 123.5 to 114 when the hairdryer is turned on. I leave the dryer on and go outside to the panel. The voltage at the AFCI for that room is 123.0. Measured 12.4 amps. A 9 volt drop in a 15 amp circuit with 14/2 wire, about 25 ft of wire max. The outlets are daisy chained as usual.
That wasn’t right.. it’s about 25’ max to the outlet from the breaker. Probably closer to 75’ of wire.This doesn't make sense to me. 6 outlets before the hairdryer and only 25' of wire? That doesn't seem possible.
Oh, those little details.That wasn’t right.. it’s about 25’ max to the outlet from the breaker. Probably closer to 75’ of wire.
I’ve now found out from the HO someone else “added some things” under the house...
Guess I’m crawling under the house now.
I hate crawlspaces..
It is 14 guage210415-2029 EDT
You list yourself as an engineer, and thus I would expect much better information on your problem.
I believe you have indicated the circuit is 15 A and on that basis I assume the wire is #14 copper or equivalent resistance per foot. You are indicating a voltage drop of 9 V at 12.4 A at the load. This alone does not tell us what kind of voltage drop occurs at the main panel with a load change of 12.4 A. But we can assume the total source impedance back to somewhere is 9/12.4 = 0.726 ohms. If the voltage back at the main panel has little voltage change for a 12.4 A load change, then most of the impedances is in the circuit from the main.
The load was on the questioned circuit when measured.It appears you have read 123.5 V on the output of the AFCi breaker that feeds the circuit in question. And that the other phase is 124.2 V. I don't know whether your 12.4 A load was on or off at the breaker output when voltage was measured. I would like to know the main panel voltage at the panel input terminals on the phase of interest with and without the 12.4 A load. Also, I want to know the two voltages on the other phase, and their relation to the voltages of the first phase. The voltage on the opposite phase should increase when the voltage on the first phase drops. If the first phase, the loaded phase, drops by 0.5 V, then I might expect the other phase to rise by about 0.25 V.
There is no great change at the panel and for this circuit my suspicion is backwired devices with the possibility of “something else” as noted in a later post by the HO. I’m investigating that this weekend.If there is no great change in the main panel input voltage from the 12.4 A load change, then you are looking for a high resistance in the 12.4 A loading circuit. You first need to make sure there is no appreciable voltage drop across the output of the AFCI breaker associated with the 12.4 A load.
I did that with a #12 thwn wire.Next you connect a long test lead to the main panel neutral bus bar to what ever locations at which you what to test voltage drop. For checking only the neutral wire voltage drop you might getaway with using the EGC. But to check both the neutral and hot wires, then an extension cord is a good long test lead.
With a knowledge of what happens at the main panel with the 12.4 A load change, then you can go to the various outlets on the circuit and see what both the neutral and hot voltage drops are at the various outlets. The 12.4 A load change should be on the last outlet of the circuit. The various voltage drops should tell you where the problem(s) are.
Agreed. With above.A single line voltage drop for #14 copper, and 12.4 A is 2.5 ohms for 1000 ft or 9 V at 12.4 A is 1000*0.363/2.5 = 1000*0.145 = 145 ft.
The above should be about correct if I didn't make any mistakes.
If you really have a long cable before the first outlet, and then closely space outlets, and your high resistance is at the first outlet, then the difference between outlets might not be much, but there would be a large drop to the first outlet. You failed to provide any good specifics on your measurements.
Agreed...Ah Gee Whiz a wilikers. Possible lightning damage 4-5 months ago? That should have been, what, the second or third thing out of their mouths after Name, address and phone number?
I'll play.210419-1644 EDT
No one has commented on my 2 to 1 voltage change ratio when loading one phase. Do any of you understand where this comes from, and what assumptions need to be made for it to occur?