UG splice and change of wire size

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wrobotronic

wrobotronic

Senior Member
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Colorado
Hello all,
I have a new residential service that I will be inspecting and the HO called me and asked if he could run 350MCM AL but wants to splice it at either end to reduce it to 4/0 AL so the wire will fit into the lugs of the ped and the panel. Is this legal? While I do not have a code section off the top of my head, I was under the impression that UG splices had to be accessible and if he does do this can he then, in turn, change the wire size at the splice point? Thank you
 
300.5 (E) Splices and Taps. Direct-buried conductors or cables
shall be permitted to be spliced or tapped without the use of
splice boxes. The splices or taps shall be made in accordance
with 110.14(B).
 
wrobotronic said:
Hello all,
I have a new residential service that I will be inspecting and the HO called me and asked if he could run 350MCM AL but wants to splice it at either end to reduce it to 4/0 AL so the wire will fit into the lugs of the ped and the panel. Is this legal? While I do not have a code section off the top of my head, I was under the impression that UG splices had to be accessible and if he does do this can he then, in turn, change the wire size at the splice point? Thank you
Click to expand...


If it were me I'd probably run the 350 all the way and then crimp on some offset Mac Adapters on each end and forget the underground splice.

JAP>
 
If it is direct buried it is allowed.

Splice wouldn't be allowed if in a raceway. I won't tell anyone if you don't though that it does happen sometimes;)
 
I would much rather land #4/0 conductors than try and struggle with 350's in a pedestal that is more likely suited for #4/0.
 
jap said:
If it were me I'd probably run the 350 all the way and then crimp on some offset Mac Adapters on each end and forget the underground splice.

JAP>
Click to expand...

You must not deal with residential equipment. The wire bending space is limited. There isn't room for large conductors and pin connectors.
 
curt swartz said:
You must not deal with residential equipment. The wire bending space is limited. There isn't room for large conductors and pin connectors.
Click to expand...
Correct, you will likely need a splice box to have room to make the reduction.

You could enter the opposite wall rather then the one adjacent to the main lugs/breaker lugs, but your large conductors and splicing methods may still take up a significant amount of wiring space in the so called "wiring channel" of the panel that will also have wiring and splicing fill limitations.

Put in AFCI breakers in some panels and you have practically no room left for 350KCMIL conductors in the wiring channel.
 
You all just must not have much expirience handling big wire... :)

Just kidding...


JAP>
 
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