DEW202001
Member
- Location
- ODENTON, MD
What do you think.
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Stripped conductors in conduit that is installed in a class 1 div 1 location
- Thread starter DEW202001
- Start date
- Status
- Location
- Massachusetts
I think there is little info here.
DEW202001
Member
- Location
- ODENTON, MD
Stripped conductors in conduit that is installed in a class 1 div 1 location
On Monday contractor test A VFD. Today they turned it back on to finish testing and it kept tripping. Megger tested the wire it failed. Pulled the wire out and found that.
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On Monday contractor test A VFD. Today they turned it back on to finish testing and it kept tripping. Megger tested the wire it failed. Pulled the wire out and found that.
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DEW202001
Member
- Location
- ODENTON, MD
On Monday contractor test A VFD. Today they turned it back on to finish testing and it kept tripping. Megger tested the wire it failed. Pulled the wire out and found that.
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- Occupation
- Licensed Electrician
Those look like busted conductors like when a backhoe digs them up.
Seen a few of those, have you? :blink:
- Location
- Illinois
- Occupation
- retired electrician
That does not appear to be recent damage based on the color of the exposed copper. Were the conductors tested before the VFD was hooked up? Were the conductors in use prior to the connection of the VFD?
DEW202001
Member
- Location
- ODENTON, MD
The cables were tested before the VFD was hooked up. No the conductors where not in use. The contractor told me that Monday they tested the VFD and everything worked fine. Then today they turned the VFD on and it kept tripping. The contractor thinks someone went back and did that to the wires.
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I agree with Don. The oxidation says it has been that way for a while. Looks like a smashed conduit with pressure enough to pull the insulation off.
just the cowboy
Inactive, Email Never Verified
- Location
- newburgh,ny
How were they to pull out?
How were they to pull out?
The stripped end looks funny, almost like the wires stretched and broke when pulling in or out!
How were they to pull out?
The stripped end looks funny, almost like the wires stretched and broke when pulling in or out!
Looks like a certain kind of automatic stripper was used on all but rightmost wire.... the kind that constricts the wire in a hole (two half holes squeezed onto insulation) then grips and rips the insulation off the end.
A backhoe could not have made those impressions.
- Occupation
- Licensed Electrician
Looks that way to me too.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
I agree, that's the first thing I thought of seeing that.
My guess:
Someone dug up a conduit with a backhoe and bent it. That made the conductors pull out of one end or the other. So even after they straightened out the conduit and reburied it so that nobody would notice, they had to pull the conductors back out of it to re-make that connection. In pulling them back through the now crushed conduit, they stretched, then snapped the conductors.
It fits that "troubleshooting flow chart" joke, where it says "Did anyone see it yet?" => No => "Hide it". This will be followed by "Does anyone know it was you?" => No => "Blame someone else!"
- Location
- Illinois
- Occupation
- retired electrician
But I still don't see it as recent damage. I really doubt the conductors were tested prior to the connection of the VFD.
DEW202001
Member
- Location
- ODENTON, MD
No they where tested. I witnessed the Meg test and have the Meg sheet.
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- Location
- Illinois
- Occupation
- retired electrician
What was in the conduit? I just do see that a recent damage unless there is something corrosive involved? Is this at a sewage treatment plant? H2S will turn copper black very quickly?
Also if the conductors are just laying loose and not touching each other or the conduit, bare ends on conductors will pass a megger test. Were they tested for end to end continuity?
Are the ends pictured both sides of the run?
If yes, that'd mean they were pulled from each end. Did anyone swab or otherwise clean out the conduit after the wires were pulled out. What I'm wondering is if they were butt spliced in the conduit and the butt connectors did not make it out.
If not, where's the other side?
If yes, that'd mean they were pulled from each end. Did anyone swab or otherwise clean out the conduit after the wires were pulled out. What I'm wondering is if they were butt spliced in the conduit and the butt connectors did not make it out.
If not, where's the other side?
wallyworld
Senior Member
If those were in a pipe how could they pass a meg test? I've seen frost break wires like that, looked like they were pulled apart. I've seen excavators make wire look like that also. They look like they've been broken for awhile but if they were submerged for a long time the wire could be oxidized like that the whole length of the run.
DEW202001
Member
- Location
- ODENTON, MD
the contractor thinks someone went back and stripped inch of the insulation off to expose the copper. When he pulled the conduit out the wires broke off.
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- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
Someone pulled the wire out, stripped off an inch of insulation, then pulled them back in again? For what purpose, sabotage to cause an explosion? That would make this a serious criminal investigation! Malicious mischief? Seems like an awful lot of effort to do that just to mess with someone. The accidental aspect an cover up seems a lot more plausible to me.
As to the discoloring, remember this is a classified area, so who knows what kind of gasses are present. A little bit of H2S in the air will discolor exposed bare copper like that in a matter of hours.
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