K&T/120 volts to ungrounded wire mesh

[iwire]

ground the mesh and see what trips

'Seeing what trips' is always a bad idea.

 

[nolabama]

i didnt say it was a good idea - but i think if the ground refernce is hot and the mesh isnt .... it wont trip anything - and i dont know but i think that if you were to ground it as a test ie short period of time - seconds - and not leave it grounded you should be fine - but... it may be a feeder issue and in that case probably not a good idea

 

[al hildenbrand]

Just curious, did you turn them all off at that same time, or did you turn each one off individually?

If you only turned one off at a time I would turn them all off and see what you have.

It is possible you have faults on two circuits or one circuit is actually interconnected in the walls somewhere.

My thoughts, exactly.

I've isolated the problem to the "A" phase.

The accidental mesh-connection of two or more branch circuit hot legs on the "A" phase, as you call it, will require shutting off the branch circuit OverCurrent Protection (OCP) (breaker or fuse) on all of those mesh-connected circuits at the same time for the 120 V to go away.

Isolating the 120 V to the "A" phase was smart trouble shooting. That's already cut the number of OCPs in half.

Turn off the "A" phase branch circuit OCPs one at a time, leaving them off. Watch for the mesh 120 V to go away. When it does, that last branch circuit OCP is one of the mesh-connected branch circuits. Leave this OCP off, and turn on all the rest of the "A" phase branch circuit OCPs, one at a time, leaving them on as you go along. When the 120 V re-appears on the mesh you have found the next branch circuit that is connected to the mesh.

Now, leave the two OCPs that you found OFF and turn all the rest on, and, if the 120 V on the mesh stays off, then there are only two branch circuits connected, if the 120 V re-appears, there's more to isolate.

 

[phattonmvp]

Close this thread?

Close this thread?

Gentlemen and Ladies- How do I close this thread and post my solution? Just do it in another reply, or is there another way to do it and let you all know how I took care of the problem?

 

[MF Dagger]

The suspense is killing me. Just post it right here. Maybe it's possible to change the title of the thread or add on to it

 

[76nemo]

Gentlemen and Ladies- How do I close this thread and post my solution? Just do it in another reply, or is there another way to do it and let you all know how I took care of the problem?

There's a limit of possibilites even if we didn't hit it. Don't start a new thread, answer the question. This wire mesh you speak of I have yet to work around. I want to know what you found myself......

 

[phattonmvp]

Solution

Solution

To Isolate the circuits, I did what AL Hildenbrand said for the most part. After I identified the curcuits (yes..... Good shootin'- there were 2 circuits on the same phase causing the problem). One circuit was "small" enough that I didn't have too much trouble locating the fault. Then I got lucky on timing.... Long story short, the fault on the other circuit happened to be on a switch-leg. Found it/Fixed it.......And the rest is history. Kinda cool though. This place has a hallway in the common area with tin ceilings and walls. I lit up a 100 watt bulb from the wall. The owner was nervous and impressed at the same time!

Thanks for your input! Pat

As for explaining the wire mesh in an old building with plaster walls.... I'm tired of typing. Can someone else handle that one?

 

[76nemo]

No need to, you found the problem. You did good! Another chapter in learning.

 

[al hildenbrand]

I lit up a 100 watt bulb from the wall. The owner was nervous and impressed at the same time!

Nothing like a teachable moment to justify the expense of the troubleshooting.

Nemo,

The metal mesh is "wire lath" or "expanded metal", and undoubtedly a bunch of names I don't know. It's been essentially the same thing for most of the last century. It's still used as the base for stucco siding up here in Minnesota.

 

[mxslick]

'Seeing what trips' is always a bad idea.

I think I already said that... :grin:

See post #18 :grin:

Glad to see the OP got to the bottom of this and solved the problem.

And thanks to Al for posting the pic to explain what we've been chattin about.