[georgemcq]

If sub panel is located in attached garage then only need 3 wires and not 4??


Thanks

 

[BRodgers]

Nowadays code requires 4 wire regardless of whether the sub panel is in the same building as the main or not.

 

[anyacolo]

4 wires,


two hot, neutral, ground

 

[brric]

Unless the sub is grounded to the main panel by connection to a metallic conduit.

 

[seharper]

Combining neutral and ground like that has long been forbidden. Doing that will allow a simple wire break to cause a particularly nasty condition.

 

[J. V.]

A sub in the same structure or dwelling (attached) requires a grounding conductor or a metallic path back to the panel.
If the feeder is run in metal conduit, only three wires are required.

If the feeder to the sub panel is cable, then yes, he must use a 3 wire cable assembly with ground.

There has been much debate over which method provides the best metallic path back to the source. Some believe conduit is a much superior path.
Some believe a grounding conductor is a superior path.

The best part is you can do it either way and be compliant.