Electrical conundrum quiz

[Bobbo]

I have solved this problem, but thought the electrical experts might try their hand at diagnosing this problem.

My father in law made a homemade extension cord. He took a 12/2 wG cable and put a plug on one end. He wired a box with a SPST ON/OFF switch to the hot wire. He then wired the other end with a duplex 15 amp outlet.

When he plugged ANYTHING into the outlet, it would not work. It was like it had no power, so he called me. (I have a reputation of being able to fix anything.)

I plugged in one of the 3 light testers.

With the power switch turned ON, all 3 lights were lit.

With the power switch turned OFF, the red and middle lights were lit up which normally indicates a hot/neutral reversal, but the right light was not on. Note that this is with the power switch turned OFF.

Anyone care to guess?

[enblethen]

How long is the run and what type of wire? It is possible that it could be induced current.

[Bobbo]

wnjj wrote:

Hiking Hunter wrote:
I'm having a hard time buying that...

I understand how a couple of loose whiskers can give a false indication for a hot-neutral reverse when the switch is open, but when you close the switch the whiskers would immediately be burned or the breaker would blow, UNLESS the whiskers provided just a high resistance connection and not a dead short. BUT, If that were the case and the breaker didn't blow, then why wasn't the load powered?

But, I don't have any better explanation.

OP, are you 100% sure of the switch ON/OFF state for the light cases? Did you re-check things after "fixing" it? Did you take apart and check all of his connections?

Yes, I am 100% sure of the switch ON/OFF state. I rechecked with the tester immediately after re-wiring the plug and everything was right. I did check his other connections, later, but they were acceptable.

wnjj wrote:

Bobbo wrote:
That let enough current go up the neutral wire to give a hot/neutral reversed test when the switch was off.

With the switch off (and truly switching the hot wire), where is there any current in the system at all?

The neutral wire was energized at the plug, before the switch, so it was hot all the time. That is why the tester showed a HOT/NEUTRAL reversal even with the switch off.

wnjj wrote:
Did you by chance take more than one wire apart in the plug and put them back correctly in the process?

No. I took each wire off, one at a time, twisted the wires and put them back in place. At no time was more than one wire loose.

Think of it this way:

1: Run ground wire to ground pin.
2: Run hot wire to neutral pin.
3. run hot wire to switch then to hot pin.

Now, with the switch off, you have hot/neutral reversal. With the switch on, you still have hot/neutral reversal, but you also have power on the third light, which is the light showing a hot/ground connection. That is the best I can describe it.

What I don't understand is why it didn't blow a fuse or burn up the strands that were crossed, since the neutral wire was also hooked to the neutral pin.

I agree that the symptoms are not explained. That is why I have posted this here, hoping someone with more knowledge can enlighten me.

[wnjj]

Hiking Hunter wrote:
I'm having a hard time buying that...

I understand how a couple of loose whiskers can give a false indication for a hot-neutral reverse when the switch is open, but when you close the switch the whiskers would immediately be burned or the breaker would blow, UNLESS the whiskers provided just a high resistance connection and not a dead short. BUT, If that were the case and the breaker didn't blow, then why wasn't the load powered?

But, I don't have any better explanation.

I agree with you. One easy way that I can explain both the 3 lights on and the hot/neutral reversed scenarios is if the system is indeed hot/neutral reversed AND the neutral wire is switched by the switch. The discrepancy with the OP is the 3 lights would then happen with the switch OFF and 2 with it ON, plus the receptacle would "work" with the switch on.

This could easily happen if the hot and neutral were swapped at the plug and the rest were wired correctly. The black wire would now be neutral but have a switch and connect to the hot terminal of the receptacle. With the switch ON, you get the 2 hot/neutral reversed lights. With if off, you get a floating neutral and 2 of the 3 lights turn on dimly (series connected between hot and ground) with the 3rd at normal brightness (between hot and ground).


OP, are you 100% sure of the switch ON/OFF state for the light cases? Did you re-check things after "fixing" it? Did you take apart and check all of his connections?

The filament being the only issue does not explain the symptoms at all. At the very least, if both the neutral and ground are connected to the receptacle at all times, there is NO way to light the red light on the tester.

Bobbo wrote:
That let enough current go up the neutral wire to give a hot/neutral reversed test when the switch was off.

With the switch off (and truly switching the hot wire), where is there any current in the system at all?

Did you by chance take more than one wire apart in the plug and put them back correctly in the process?

[Bobbo]

Chris Bryant wrote:
Did the outlet tester use LEDs or neon bulbs?

Don't know. How do you tell?

Hiking Hunter wrote:
I'm having a hard time buying that...

I understand how a couple of loose whiskers can give a false indication for a hot-neutral reverse when the switch is open, but when you close the switch the whiskers would immediately be burned or the breaker would blow, UNLESS the whiskers provided just a high resistance connection and not a dead short. BUT, If that were the case and the breaker didn't blow, then why wasn't the load powered?

But, I don't have any better explanation.

I just report what I found. I don't understand it either. I even said so in the explanation I gave above.

Matt_Collie wrote:
Maybe -
Just Maybe,
This is why you are not supposed to put stranded wire under the screws of MOST wire devices with the singular exception of those designed for stranded wire.

His electrical work is not up to par. He installed an electric water heater, including running the wire from the fuse box. While he put in a 30 amp shut-off switch, he wired it directly to TVA. He did not run it through a circuit breaker. When I discovered that, I, ummm, rewired it.

[enblethen]

The better receptacles are back wired with plates. You stick the stripped wire to correct length, insert through the back between the buss and clamp, then tighten screw.

[Matt_Colie]

Maybe -
Just Maybe,
This is why you are not supposed to put stranded wire under the screws of MOST wire devices with the singular exception of those designed for stranded wire.

Matt

[Hiking_Hunter]

I'm having a hard time buying that...

I understand how a couple of loose whiskers can give a false indication for a hot-neutral reverse when the switch is open, but when you close the switch the whiskers would immediately be burned or the breaker would blow, UNLESS the whiskers provided just a high resistance connection and not a dead short. BUT, If that were the case and the breaker didn't blow, then why wasn't the load powered?

But, I don't have any better explanation.

[enblethen]

High resistance just acted like a filament in a lamp.

[Chris_Bryant]

Did the outlet tester use LEDs or neon bulbs?

[Bobbo]

OP here. I should have added that the outlet he was plugging into to power this monstrosity was wired correctly and tested correctly.

Here is what I found.

He wired everything correctly. BUT! He used stranded wire and did not get all of the strands under the screws in the plug. One or two of the strands from the hot wire were touching the neutral screw inside the plug.

That let enough current go up the neutral wire to give a hot/neutral reversed test when the switch was off. When turning on the switch, that also energized the hot wire lighting it up too. I guess it also gave enough hot current on the neutral to keep 120v stuff from running, since both hot and neutral were at the same voltage.

What I don't understand is why it didn't either blow the fuse (old house) or heat up enough to start a fire or at least burn up those 1 or 2 wires.

I loosened the screw, twisted up the stranded wire and got all of the strands back under the screw, and it works just like it should.

[MEXICOWANDERER]

Ground can CHEAT for neutral. I'll repeat what I wrote in my post above - doing this is NOT RECOMMENDED.

[road-runner]

I intuitively think there is more than one way this could happen. There are 2 ways all 3 lights could be on:

1) The tester allows 2 lights to light up in series when one of the three outlet prongs is open.

2) One of the 3 outlet prongs has a voltage in the neighborhood of 60.

So I'd guess there's either an open conductor or unwanted high-resistance leakage involved.

[msiminoff]

Bobbo wrote:
Anyone care to guess?

Sure, I'll take a stab...

To eliminate variables, I'm gonna say (hope) that the plug was correctly wired.
But then your FIL wired the outlet as follows; Hot wire to the ground pin, neutral wire to the hot pin and the ground wire to the neutral pin.
And finally...he wired the switch into the neutral wire.

Interested to learn what actually happened.
Cheers,
-Mark

[MEXICOWANDERER]

Black-white-green

Line-neutral-ground

Colors are there so innocent don't get zapped

Naughty -Naughty-Pants-On-Fire

[MrWizard]

nineoaks...wrong

on AC power, you always switch the HOT