Three wires from the clothes dryer – ground or neutral?

[Mike Lamb]

There are three wires running from an electric dryer to a condo subpanel. Would it make sense that the green wire is a neutral for 120 V from the dryer or would that need 4 wires? Or is this a ground that should be isolated from the neutral bar on the panel?

[Jim Katen]

Assuming that this is a pre-1996 installation, when 3-wire dryer circuits were still allowed, then my best guess is that the green wire is the neutral and is best terminated on the neutral bar because it carries current and you want to keep that current off the equipment grounding terminal bar. (Of course, it's not supposed to be green - that's probably the error here.) 

[Mike Lamb]

It's new laundry equipment.

[mjr6550]

I agree with Jim. 

The age of the equipment does not matter.

At least the wire in insulated. I see many old installation with two conductor and an uninsulated ground. That was permitted using SEC, but not NM.

[inspector57]

My guess based on the type of wire is there is likely metallic conduit which could be the ground and the green wire should be white for a dryer neutral. So other than insulation color the installation is about as good as it gets without a rewire to pull a 4th wire.

[John Kogel]

Right, if the dashboard lights on that washer come on and it is in working order, 1) good bet that 3rd wire is the neutral.

2) My Xray vision sees conduit. Chicago has strict rules and a strong union, per Br Kurt. So it is grounded as well.

 

[Marc]

One of my more commonly used boilerplates:  If your electrician says you don't need it because the house is old, fire him and find someone else.  Electricity doesn't know how old the house is and doesn't care.  It'll shock folks and start fires just as easily on an old house as it will on a new one.

If the wireway is metallic, then that green neutral should be replaced with a white one.  If it's not metallic, that dryer needs four wire service.

Edited June 12, 2017 by Marc