Double-pole breaker not tripping

GaryS · Mar 29, 2019

There are a number of things to look at
when you measure the voltage always measure Hot to Hot, Each Hot to Nut, each Hot to Ground and Nut to ground this will give a clear picture of the voltages
It is possible one leg of the breaker is open and with the load connected both legs will be powered from the same hot leg.
You could have an open Natural so shorting any hot to nut will not trip the breaker.
All Neutrals are required to bonded to the ground at the main panel if the branch is feed from a sub panel the neutral and ground in the subpanel are isolated in the subpanel
As stated before it is never a good idea to short wires to find the breaker I have seen many breakers where the contacts welded together from a short and they will never open.

janner_10 · Mar 29, 2019

tragically1969 said:
Anybody seen playing that game in the UK would find themselves without a job pretty quickly.

Many years ago, this was the last resort to finding a breaker! There we no fancy gadgets, you just cut, mind you, this was on T&E, sod doing on SWA!

Rob... · Mar 31, 2019

janner_10 said:
Many years ago, this was the last resort to finding a breaker! There we no fancy gadgets, you just cut, mind you, this was on T&E, sod doing on SWA!

We had a spiking gun for the big HV cables, do everything possible to proove its dead before splitting the cable for a joint.

However rather than some poor sod cutting the cable with a small chance of it still being energised, strap a small charge to it that fired a blade through all the cores. If it wasn't dead, the circuit protection would activate.

Aabeck · Mar 31, 2019

I occasionally work alongside an electrician that complains about the water in Lake Erie.

He was working on a boathouses wiring and wanted to trip the breaker in the house so he pulled the live cable and threw it in the water to trip it. Not enough current was going through the water to trip it. Bad water obviously.

da_mule · Mar 31, 2019

jraef said:
Since we have to guess, my guess is that this was a DIY hack job done by someone who didn't know what they were doing, and they used a "twin" breaker as if it were a two pole breaker. that doesn't work because on a twin, both poles are connected to the SAME leg of the 240V lines. So there is zero potential between them. Given the improper connection to the hots, it's highly likely that the original installer didn't connect the ground correctly either.

And yes, that would have meant your heater never worked, unless said nincompoop rigged the heater to go to ground at it's connection box, in which case it was a 240V heater (illegally) getting 120V and would have been giving out a lot less than rated heat. In fact come to think of it, that might explain the "low spark of high heeled boys" you experienced, because that would put the heating element(s) in SERIES with your supposed short circuit test.

Traffic fan?

willxfmr · Apr 1, 2019

rguimond said:
I apologize in advance if this is off-topic, but I really need to understand what's going on...

While doing some renovations, it was found necessary to relocate a few runs on BX (aluminum-sheathed) cable. One of the cables ran between a single-pole thermostat and a 240V baseboard heater. After trying unsuccessfully to locate the breaker, I turned up the thermostat to ensure both hot lines were energized and cut through it (while wearing arc-flash protection, or course), with an old set of linesman's pliers.

Guess what? The breaker didn't trip! I stripped off a few inches of aluminum sheathing and bared the ends of both hot conductors. When I touch them to the ground conductor, there is only a very small spark and the breaker DOESN"T TRIP, even after holding it for several seconds.

Definitely a top-ten entry in my weirdest encounter.

Any suggestions, guys?

Gotta love it when a guy is still willing to kick it old school!

Based on what you have described, the original install was a complete botch job. While it is possible that you have a bad breaker, but the noise alone would be enough to make you nervous while holding the hot to the ground. *Please don't ask me how I know this to be true* It sounds to me like this heater has no ground, and may of been wired for 120v and not 240v. Personally I would either trace the entire wire run back to the source and then hook it up correctly or I would trash the old wire and start over fresh. If at any point from the heater to wherever it gets power you can't see the cable, then forget fixing it and start over. I have seen too many examples of splices buried in walls and ceilings where you can't see them to trust that it enters and leaves someplace I can't see and something stupid wasn't done in between.

Bubba.

Double-pole breaker not tripping

GaryS

Member

janner_10

Lifetime Supporting Member

Rob...

Lifetime Supporting Member

Aabeck

Member

da_mule

Member

willxfmr

Lifetime Supporting Member

Similar Topics