Metal Clad Cable

[djcrzysounds@yahoo.com]

This really has no place in the forum, however I thought this to be the best place.

Received a call today from a plumber. He was working above a drop ceiling and "bumped" a #1-3 Conductor (plus ground) cable. Cable goes about 65 feet from Single Phase 120/240V Fused Disconnect (Fused at 100 Amps) and feeds a sub panel. He said he called another electrician before me and was told that it was an overloading issue and that the owner would need to put a new service, disconnect and sub-panel in. I didn't do much investigation seeing as it wasn't a service call for me but assisting a friend. Any thoughts?

 

[infinity]

My thought is how is it overloaded when #1 conductors are protected at 100 amps? Sounds like part of the story is missing.

 

[djcrzysounds@yahoo.com]

There is a lot of the story missing, however I'm not investigating this on my dime. I'm just asking around on the forum to see if maybe I missed something. I figured it for an improper grounding and/or bonding situation.

 

[jim dungar]

There certainly is a lot missing.

What is the problem/concern/issue?

 

[mivey]

I'm just asking around on the forum to see if maybe I missed something.

I say yes.

I figured it for an improper grounding and/or bonding situation.

Based on what? Sounds like we got part of the part of the story you got.

 

[Smart $]

There is a lot of the story missing, ...

Your opening post makes it sound like this plumber called you because he "bumped" the MC cable.

You must be a good friend if he called you for this reason

 

[jumper]

What does "bumped" a cable mean?:-? And how does this "bumping" all of a sudden require a new service?

 

[LEO2854]

What does "bumped" a cable mean?:-? And how does this "bumping" all of a sudden require a new service?

Maybe the plumber saw sparks

 

[jeremysterling]

Maybe the plumber saw sparks

As when the plumber "bumped" it with the sawzall or torch flame...

 

[djcrzysounds@yahoo.com]

What is the problem/concern/issue?

The initial concern was what the possible cause(s) were for this issue.

As when the plumber "bumped" it with the sawzall or torch flame...

As in bumped it with nothing that would harm the cable.




Upon further investigation today(cause I couldn't stop wondering why). I found the following.

1. Ground Electrode Conductor terminated to Neutral Lug in disconnect (isolated but bonded with that cute little green screw)

2. Equipment Ground of MC terminated to Ground Lug in disconnect

3. Grounded Conductor of MC terminated to Ground Lug in disconnect(attached via screws to disconnect enclosure)

4. Grounded Conductor of Service Cable terminated to Neutral Lug in Disconnect

I did a voltage reference of the Equipment Ground of MC to the Neutral of the MC in Disconnect there was a potential of 18 Volts. This is another case of poor workmanship. After terminating everything the 'right way' (even though the way it was, was still code) There was no potential and no more arcing between the MC and ceiling grid. I guess there is high resistance via the bonding connection.

 

[jeremysterling]

.....


2. Equipment Ground of MC terminated to Ground Lug in disconnect

3. Grounded Conductor of MC terminated to Ground Lug in disconnect(attached via screws to disconnect enclosure)


I did a voltage reference of the Equipment Ground of MC to the Neutral of the MC in Disconnect there was a potential of 18 Volts...

(I'm guessing an improper neutral bond) yet,

how is there 18V when they are connected together in the disconnect?

 

[djcrzysounds@yahoo.com]

There is a current on the neutral. My thoughts were poor bonding between the Grounded Cond and the ground.

 

[LarryFine]

Obviously, "bumped" means "touched and shocked by" to the plumber. Make note.

 

[mivey]

Obviously, "bumped" means "touched and shocked by" to the plumber. Make note.

I'm glad that's clear. I was beginning to think he needed to hire the plumber. Anyone that can just bump into things and tell if they are overloaded or not would be a valuable addition to the team.

 

[mivey]

I can't help but look at a re-cap:
#1) Plumber bumps into a cable and determines it is overloaded (method of determination unknown)
#2) Infinity say: What?
#3) OP asks for input without telling us what is going on.
#5-#9) Members ask: What in the world are you talking about?

#10) Play-by-play:

The initial concern was what the possible cause(s) were for this issue.

Issue? What issue are you talking about?

As in bumped it with nothing that would harm the cable.

So what's the problem then?

Upon further investigation today(cause I couldn't stop wondering why).

"Why" what? For goodness sake, this is death by a thousand cuts.

...
There was no potential and no more arcing between the MC and ceiling grid.

Whew! This is worse than cliffhangers before the season finale. :grin:

DJ: you forgot to tell us about the arcing at the beginning. :grin:

 

[SegDog]

do the bump...

do the bump...

This gives me chills.

The last time a plumber bumped something, the plumber actually installed unknown type of refrigeration equipment, and "bumped" a wire down to a high-leg in the panel. The smell of burning insulation got someones attention. Afterward, someone called and did not tell the whole story. Needless to say, troubleshooting was not easy.

 

[sparky59]

I'm confused.

 

[jeremysterling]

I'm confused.

If you think you're confused, consider the poor plumber that said he got electrocuted by a cable only to be told it was just a "bump."

 

[mivey]

I'm bumped.

 

[Saywatt]

Bump to the top.