3 Wire 220 Volt Outlet

theatretch85

I feel kinda stupid asking this question, but the labeling on the outlet threw me for a loop. Its a 50 Amp 3 wire plug, the particular one I have is the Pass and Seymour 3890-CC6. This will be wired up for a temporary use on a stove that I currently do not have access to. Normally i'd wire it up with Red Black and Green since a 240volt 3 wire plug would have a ground and no neutral. I don't know if the stove has any 120volt parts on it (I am going to assume not). The back of the outlet marks the center pin as "white". I will be wiring this up with a 3 wire cable into a sub panel that has the neutral and ground separated on it, and when I do get to the point of using this next weekend I could change the bus bar the center pin connects to pretty easily. I would think that if the stove does not have any 120volt parts, that center pin should be Ground, not Neutral.

One thing I just thought of, with the center pin being flat (not U or round shaped) it should be connected to the neutral bus verses the ground bus. Would that make sense?

Below is an image of the outlet I am working with:

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Stubbie

That is a nema 10-50R 3 wire range receptacle. Two hots and neutral. If the stove is 240 only then you should be using a 6-50R. but to answer your question 3 wire range with a neutral is only allowed for existing permanent installations. Otherwise 4 wire supply is required.

That receptacle will work as you want with 240 volts only by using the ground connected to the neutral terminal (W). However this is not the intent for that receptacle.

theatretch85

I understand the whole reason behind the 4 wire and that it is code in the 2008 book. This is for a temporary use of a stove for 1 or 2 days. Big wedding going on at a buddies farm house, and temporarily tapping power for several hot plates, this stove, some stage lighting and power for sound. Thankfully the heat items (hot plates and stove) won't be on at the same time the bands will be playing and the stage lighting being on.

The way I understood it, 3 wire range outlets were wired up with a ground, not a neutral. But thinking about how a 4 wire plug is wired, the center flat pin is the neutral, and the U shaped or rounded pin is the ground. So my guess with this outlet would be that since the center pin is flat, it should be wired to the neutral (as the outlet is labeled) and if it had a U shaped pin it would be ground. So the only question that I think I will need to answer is if the cord on the stove is original or not.

Stubbie

You would not be alone in thinking it was a ground. However 3 wire ranges were 120/240 so needed as you know a neutral. In application the neutral was bonded to ground (metal frame) at the range terminal block so the neutral played double duty as ground and neutral. This configuration has been documented to several electrocutions over the years and now is no longer allowed but existing ones are out there by the 100's of thousands there fore the exemption but no more are to be allowed.

frenchelectrican

The netual wire on the range is double duty on three wire verison it used for both netural and ground as you can see if you look at the termail block on back of the range.

Yep right on the target and myself I will not install the three wire range receptale for tempory useage heck no way.

Merci,Marc

theatretch85

Just thought i'd post back, this particular application the stove was a 120/240 so the center pin is/was a neutral.