Reducing 750 Aluminum

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Transportation Guy

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Williamsburg,VA
Morning! An engineer designed a project we are doing (2 of them) with a 750 Aluminum secondary run instead of parallel runs. We didnt have time to wait for an RFI answer as the slab was being poured and were told to "install per plan". We now have 1 ea 4" PVC in the slab for this 750 Aluminum run. The issue is now with the power company. They cannot terminate 750 in their transformer and 750 will not fit in the meter base. (we cant get the meter for 8 months anyway due to the crisis we are all facing with electrical gear lol) Can we use the tap rule in 240.21 and reduce the wire size that will fit in the lug? I checked on the pin reducers and these will not reduce the 750 down small enough.

Been a while since I was on the forum. Good to be back on!

Thanks all.
 
I don’t think you can use the tap rule because the tap must terminate on an OCPD.

8 months is enough time for the engineer to respond to an RFI and design a (at this point, expensive) fix. It’s his problem. Concrete demo is easier the sooner it’s done after the pour!
 
750 in a Meterbase?
This isn’t a transformer rated meter installation?
As far as the XF, they make two hole spades for 750
 
Sounds like this is service conductors so tap rules in 240.21 don't apply to it anyway.

Also on the utility end most cases NEC doesn't apply and POCO can do whatever they want with that end. Mostly depends on where the "service point" is as to whether NEC applies or not.

All that said, still nothing wrong with reducing this conductor at terminations if it is increased in size for voltage drop reasons. But if you need the selected size as the minimum ampacity, reducing it is going to mean higher termination temperature is a possibility than if it were not reduced. But again in most similar situations that is more of a POCO issue than an NEC issue.
 
Is there any way you could install a JB with a Stud Block and transition to parallel from there? I've done this for transition from finely stranded wire to Code wire.
 
petersonra said:
can you run an adequate number of parallel conductors in the 4" pipe?
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That's what I was going to say, smaller conductors are so much more efficient that usually even after the derating you end up ahead.

Some more details would be prudent too, the 750 landing in a meter base is strange. Is this a class 320 socket? Or a CT can?
 
Polaris taps to smaller copper. If this is a non-CT meter base, then it’s probably 400 amp or less, so is the engineer requesting 750 for voltage drop? If so, the wire size can be reduced substantially using the Polaris taps, or the compression lugs as Augie47 suggested.
 
Also why is the neutral full size? It could be 500 or smaller, unless you have mostly line to neutral loads.
And a 1/0 to a ground rod?
Some value engineering is needed.
 
don_resqcapt19 said:
Those are not actually permitted as the termination lugs are typically listed for use with Class B or C stranded conductors, and not solid conductors as that pin adapter has. There is at least one brand of reducer that has a stranded conductor for the pin that wold be permitted.
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I don't believe any of them at that size are actually listed anyway.
 
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