Three conductor feed to garage 2 awg 100 amp service

[SDW7613]

My friends garage has a Three conductor feed 2 awg Al to a 100 amp panel. The garage is fed from a 2 pole breaker in house main panel. Is this set up ok?

 

[augie47]

(a) you did not identify the type conductor but, at best, it's one rated at no more than 90 amps and should be protected accordingly.
(b) There would need to be an EGC with the circuit.

 

[SDW7613]

It is a UF XLPE 2-2-4. If it is already installed. Can you install a ground rod for the garage? Was this accepted under old code before 2008?

 

[infinity]

It is a UF XLPE 2-2-4. If it is already installed. Can you install a ground rod for the garage? Was this accepted under old code before 2008?

Prior to 2008 NEC yes it was permitted. The garage requires a grounding electrode system.

 

[winnie]

Two issues to clarify: prior to 2008 you were permitted to use the neutral as your fault current path rather than an EGC, but only in the limited case of an outside feeder with no other metallic paths between buildings. No shared pipes, no grounded coax, etc.

If this system was installed in this fashion, grounding electrodes are required at the outbuilding, but these cannot substitute for the EGC. The panel at the outbuilding needs to bond the neutral to provide the fault current path.

The use of #2 Al for residential 100A installations is a common error. #2 Al is specifically allowed for a residential main service conductor, and this allowance is frequently but erroneously applied to things such as garage feeders.

Jon

 

[SDW7613]

Copy thank you.

 

[infinity]

I would add one more thing whether you use a 3-wire or 4-wire feeder the separate structure requires a GES.