Damaged cable connection at MCB

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olc

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Hopefully you can see the attached photo. It is the service entrance connection to the main circuit breaker.
What do you think?
Overload?
Bad (not tight) connection?

609 service.jpg
 
petersonra said:
Is that fine stranded conductor on standard lugs?
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Don't think so, although I see what might be making you think so, what looks like a few stray very thin strands poking out of the left side there.

But it says 500MCM cable made by Pirelli, looks like EPR and if so, the current version of that (Pirelli is now Prysmian) shows it as Class B stranding as standard. If it were DLO cable with type K standing, it would not be exactly 500MCM. Usually the number is odd, like 444.4 MCM or 535.3 MCM.

I'd say the lug was not tight and the cable over heated. B phase looks a little on the brownish side as well. What's the load? I know people often thought they were getting away with higher amperages by using the Pirelli cable, because their literature would give you a higher amperage than the NEC, but that doesn't actually matter. If you look, their literature says the 500MCM is good for 700A, the NEC says 380A when you have 3 of them and you use the 75 degree column.
 
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Overloading possibly,
I'd say overheating due to oxidation and poor connection.
 
May have been tight when new. May not have been tightened to recommended tightening torque (over or under), may have required joint compound to be used in the connection. One or more of those things probably led to it no longer being a good connection. Conductor appears to been manufactured in 1979 - that seems to be somewhat expected life for this kind of thing.
 
Jraef said:
Don't think so, although I see what might be making you think so, what looks like a few stray very thin strands poking out of the left side there.

But it says 500MCM cable made by Pirelli, looks like EPR and if so, the current version of that (Pirelli is now Prysmian) shows it as Class B stranding as standard. If it were DLO cable with type K standing, it would not be exactly 500MCM. Usually the number is odd, like 444.4 MCM or 535.3 MCM.

I'd say the lug was not tight and the cable over heated. B phase looks a little on the brownish side as well. What's the load? I know people often thought they were getting away with higher amperages by using the Pirelli cable, because their literature would give you a higher amperage than the NEC, but that doesn't actually matter. If you look, their literature says the 500MCM is good for 700A, the NEC says 380A when you have 3 of them and you use the 75 degree column.
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Ditto, I concur with you. I would question the bending radius also. It seems tight to me as it appears as though there is a lot of stress on the terminals.
 
templdl said:
Ditto, I concur with you. I would question the bending radius also. It seems tight to me as it appears as though there is a lot of stress on the terminals.
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Bending radius could be a factor in this failure. The same equipment today maybe has more bending space designed into it. One has to assume the right termination had less stress on it then the left terminal because of bending issues FWIW.
 
kwired said:
Bending radius could be a factor in this failure. The same equipment today maybe has more bending space designed into it. One has to assume the right termination had less stress on it then the left terminal because of bending issues FWIW.
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Back in the late 70s, a Pirrelli rep was on a road show tour hawking their EPR cable as having a tighter bend radius than THHN, because the EPR insulation was softer. Nobody at our mill bought into this, but I wouldn't be surprised if lots of people did. They pushed it hard back then because their cable was a lot more expensive, so they sold it based on other perceived benefits, some of which were bogus because the NEC wasn't going to allow it anyway.
 
Jraef said:
Back in the late 70s, a Pirrelli rep was on a road show tour hawking their EPR cable as having a tighter bend radius than THHN, because the EPR insulation was softer. Nobody at our mill bought into this, but I wouldn't be surprised if lots of people did. They pushed it hard back then because their cable was a lot more expensive, so they sold it based on other perceived benefits, some of which were bogus because the NEC wasn't going to allow it anyway.
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Some equipment manufacturers don't seem to care about bending radius. Sure their equipment is often listed as is but I've seen larger AWG THHN bent at about as close to a true square turn as on would think is physically possible, obviously with the help of some tool to make the bend but very tight turning radius, like about the diameter of the conductor, and the insulation remains intact
 
Trying to address this issue is like shooting at shadows without knowing the with size an if it is class B or C stranding.
No matter what game the salesman plays with boasting adoit his insulation the give stranded wire size will consist of 7, 19, 37, 61 stands each strand a specific awg. As such a size 1/0 with class B stranding will consist of 19 strands of .0745 Cu wire. You still have to bend that.
In addition there is still NEC art 312.6(a) and (B) minimum wire bending radius. How does the salesman state the advantages of his super duper cable here?
 
templdl said:
Trying to address this issue is like shooting at shadows without knowing the with size an if it is class B or C stranding.
No matter what game the salesman plays with boasting adoit his insulation the give stranded wire size will consist of 7, 19, 37, 61 stands each strand a specific awg. As such a size 1/0 with class B stranding will consist of 19 strands of .0745 Cu wire. You still have to bend that.
In addition there is still NEC art 312.6(a) and (B) minimum wire bending radius. How does the salesman state the advantages of his super duper cable here?
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By submitting Public Input and getting a code change that allows his product;);)
 
kwired said:
By submitting Public Input and getting a code change that allows his product;);)
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I'd venture to guess that the salesman has little to know knowledge about the NEC and UL requirements. He probably is what you call a peddlee. If he is selling cable he should be aware as to what UL486a has to do with the product he is attempting to get you to buy. Is he even aware if his wire is included in NEC 310?
 
templdl said:
I'd venture to guess that the salesman has little to know knowledge about the NEC and UL requirements. He probably is what you call a peddlee. If he is selling cable he should be aware as to what UL486a has to do with the product he is attempting to get you to buy. Is he even aware if his wire is included in NEC 310?
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Unless selling something that has tight controlled substance type of regulation you can sell about anything to whoever you want or whoever is willing to buy.

If he is not aware of any rules/regulations related to whatever he sells even rules that only apply to the final user, he will not be as successful selling to professionals that are aware of the rules that apply to them. He may be successful selling to others that don't know any better.
 
templdl said:
I'd venture to guess that the salesman has little to know knowledge about the NEC and UL requirements. He probably is what you call a peddlee. If he is selling cable he should be aware as to what UL486a has to do with the product he is attempting to get you to buy. Is he even aware if his wire is included in NEC 310?
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I don't see EPR insulated wire anywhere in article 310.
 
templdl said:
In addition there is still NEC art 312.6(a) and (B) minimum wire bending radius. How does the salesman state the advantages of his super duper cable here?
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Actually, the NEC has requirements only for the space at the terminals not for the actual radius of the conductor.
 
anybody notice

anybody notice

anybody notice that the phase conductors are in one conduit and the ground/bare? neutral in seperate conduit?? hysteresis effect??

Is the bare wire right next to live unprotected bus bars??
 
kwired said:
Some equipment manufacturers don't seem to care about bending radius. Sure their equipment is often listed as is but I've seen larger AWG THHN bent at about as close to a true square turn as on would think is physically possible, obviously with the help of some tool to make the bend but very tight turning radius, like about the diameter of the conductor, and the insulation remains intact
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Cable benders... :happysad:

https://www.youtube.com/watch?v=WzyUBFAo6yQ
 
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