ECN Forum Forums General Topics of the Trade General Discussion Area Ground Wire On 220V Receptacle with BX or EMT

Should a ground wire be run back to the neutral bar in a main panel or to the ground bar in a subpanel for a 220V receptacle circuit when using metal conduit or bx and all metal boxes or should the ground pin on the receptacles just be tied to the metal box. If it's just tied to the box, what size wire is required for various amperages?

If one is using common bx with black/red/white wires, should one put the white on the ground pin and tape it green at the recept. and the panel? Is the ground pin suppossed to be tied to the box whether you run the ground wire back to the panel or not?

Would the awnser be the same for New York City as for most other places?

It all depends...

Sometimes, the job will spec a seperate ground wire. By code, EMT is permitted as the grounding path, and a ground wire does not have to be run in EMT. (Sorry, i dont have the book in front of me, so i cant tell you the section.) Usually, a seperate ground wire is run for an added measure of safety.

BX is rarely used anymore, and it does not contain a ground wire anyway.

A receptacle must always be bonded to a metal box, unless it is a self-grounding receptacle. if a ground wire is run, it must be bonded to the box and the receptacle, again, unless it is a self-grounding recetacle. (the ground wire still must be bonded to the box in this case)

Wire gauges are as follows:
15 amp=#14
20 amp=#12
30 amp=#10

The grounding jumper must always be the same size as the circuit conductors.

I don't believe it is allowed to recode a white wire green the way you described. if you are using AC (BX), the metal sheath serves as the ground, so I don't see why you would need to use the white wire as the ground anyway. All you would have to do is bond the receptacle to the box, and it would be grounded.

See the 2002 NEC:

310.12 Conductor Identification

(B) Equipment Grounding Conductors.

Equipment grounding conductors shall be in accordance with 250.119.

250.119(B) Multiconductor Cable.

Where the conditions of maintenance and supervision ensure that only qualified persons service the installation, one or more insulated conductors in a multiconductor cable, at the time of installation, shall be permitted to be permanently identified as equipment grounding conductors at each end and at every point where the conductors are accessible by one of the following means:

(1) Stripping the insulation from the entire exposed length

(2) Coloring the exposed insulation green

(3) Marking the exposed insulation with green tape or green adhesive labels


[This message has been edited by Joe Tedesco (edited 06-22-2002).]

I might be mistaken but, I thought that only conductors either #8 or #6 (can't remember which size)or larger were allowed to be phase taped or otherwise identified. Smaller conductors are required to be the proper color for thier entire length.

Someone correct me if I'm wrong.