Wiring the ground or not ?

Thread Starter


Joined Nov 29, 2005

Wiring a 240VAC main breaker panel to a sub-panel; have the red, black and white AWG10 conductors.

Neutral--------------------white-------------------neutral strips bonded to metal boxes both ends.

Do I have to add
Ground--------------------green------------------ground connected to both metal boxes.

What does the redundancy achieves ?
If yes, can the ground be AWG18 ? Seen that in older installations.


Joined Apr 3, 2014
In the US, the Neutral conductor and the Ground conductor are NOT the same. The Neutral conductor carries the return current for either of the two Hot conductors. Neutral should only be connected (bonded) to Ground in one place. This is usually in the main disconnect breaker panel. This is per NEC code.

Ground does not normally carry current. It exists to carry current ONLY in the case of a fault. For example if the Hot wire inside the chassis of a metal appliance contacted the chassis the current would return via Ground.

You DO need to add a ground. The wire gauge will depend on the breaker used to feed the sub panel. Given that you're using 10 AWG for Hot and Neutral, you should use 10 AWG for Ground as well.


Joined Jul 18, 2013
The very best reference is the Book On Grounding by Eustace Soares, it is published and used by the IAEI International Assn. of Electrical Inspectors and NEC, CEC use it as a reference.
I picked up a brand new copy off AbeBooks for $1.00!!