Derating conductor due to pin type crimp for lug compatibility?

[Aldoni]

An existing 600kcmil conductor needs to fit into a 500kcmil lug.

Since the pin type crimp being proposed is reducing the cross-section of the conductor, should a 600 kcmil conductor be derated? I had no luck finding anything applicable in NEC, other than temperature derating. Can you point me in the right direction for more reading?

Thanks.

 

[infinity]

I don't believe that any derating is required.

 

[Carultch]

An existing 600kcmil conductor needs to fit into a 500kcmil lug.

Since the pin type crimp being proposed is reducing the cross-section of the conductor, should a 600 kcmil conductor be derated? I had no luck finding anything applicable in NEC, other than temperature derating. Can you point me in the right direction for more reading?

Thanks.

Given that you are fitting it in to a lug rated for 500 kcmil, I would expect it to be limited to 380A, assuming it is a copper-bodied pin crimp. That lug is rated for current in the context of a max 500 kcmil wire connected to it, and isn't going to be rated for you to force-feed 420A through it.

 

[drktmplr12]

Given that you are fitting it in to a lug rated for 500 kcmil, I would expect it to be limited to 380A, assuming it is a copper-bodied pin crimp. That lug is rated for current in the context of a max 500 kcmil wire connected to it, and isn't going to be rated for you to force-feed 420A through it.

This is from Islco catalogue. Reduces from 600 to 350 and rated for full ampacity of incomign conductor. Not clear what OP intends to use, but they didn't provide a part number or cut sheet. Can't say what it's rated for, but I doubt any derating is needed.

 

[kwired]

Given that you are fitting it in to a lug rated for 500 kcmil, I would expect it to be limited to 380A, assuming it is a copper-bodied pin crimp. That lug is rated for current in the context of a max 500 kcmil wire connected to it, and isn't going to be rated for you to force-feed 420A through it.

And if the conductor is large because of voltage drop there probably isn't a problem.

If the conductor is large because of load it carries, most likely the lug on equipment would have been selected to accept larger conductor.

 

[drktmplr12]

And if the conductor is large because of voltage drop there probably isn't a problem.

If the conductor is large because of load it carries, most likely the lug on equipment would have been selected to accept larger conductor.

i don't see a problem even if the circuit is not upsized for VD provided the proper pin reducer is selected.

most of the time we run into this is because we oversized parallel sets for voltage drop, and the manufacturer's breaker can only accept #350's. We've also seen where the breaker installed is a 1200, with three sets of 600s specified. But the breaker supplied with 4 #350 per phase.

 

[infinity]

i don't see a problem even if the circuit is not upsized for VD provided the proper pin reducer is selected.

most of the time we run into this is because we oversized parallel sets for voltage drop, and the manufacturer's breaker can only accept #350's. We've also seen where the breaker installed is a 1200, with three sets of 600s specified. But the breaker supplied with 4 #350 per phase.

If the breaker has 4-350's holes how would using pin adapters on 3-600's be code compliant? If 3-350 conductors are not large enough for 1200 amps how do the pin adapters that fit in the 350 holes make them large enough to handle 1200 amps?

 

[steve66]

If the breaker has 4-350's holes how would using pin adapters on 3-600's be code compliant? If 3-350 conductors are not large enough for 1200 amps how do the pin adapters that fit in the 350 holes make them large enough to handle 1200 amps?

I would have thought the same thing (the reduced area of the termination should reduce the amapacity). But according to drktmplr12's

post, that's not what happens - 3 sets of 600's landed in the smaller holes give the full rating of 3 600's.

Makes sense - wire ampacity is determined by max. temperature, and the short length of the reduced size of the termination probably wouldn't result in a increased temperature. Most of the heat would flow to the wire or lug.

I assume there isn't any particular rating associated with each hole on a lug either - each lug just has a total rating. And I would assume Islsco has had these adapters tested and listed them for a use with a variety of lugs.

 

[infinity]

I would have thought the same thing (the reduced area of the termination should reduce the amapacity). But according to drktmplr12's

post, that's not what happens - 3 sets of 600's landed in the smaller holes give the full rating of 3 600's.

Makes sense - wire ampacity is determined by max. temperature, and the short length of the reduced size of the termination probably wouldn't result in a increased temperature. Most of the heat would flow to the wire or lug.

I assume there isn't any particular rating associated with each hole on a lug either - each lug just has a total rating. And I would assume Islsco has had these adapters tested and listed them for a use with a variety of lugs.

Ah I see that now, had trouble reading his graphic on my phone. I believe that you're correct, the tiny amount of 350 in the terminal would not have much of an affect on the ampacity.

 

[don_resqcapt19]

Note that many of those have solid pins and the lugs are often only listed for use with Class B of C stranded conductors.

 

[drktmplr12]

the other option is a Polaris tap, provided your OCPD protects a 500 kcmil.

 

[kwired]

i don't see a problem even if the circuit is not upsized for VD provided the proper pin reducer is selected.

most of the time we run into this is because we oversized parallel sets for voltage drop, and the manufacturer's breaker can only accept #350's. We've also seen where the breaker installed is a 1200, with three sets of 600s specified. But the breaker supplied with 4 #350 per phase.

If the conductor were not upsized (VD or ampacity adjustment) then you would think it should fit in the lug if the device were supposed to be able to handle the same amps as the conductor.

I agree that certain situations of paralleling can throw a wrench into the gears though.