220 outlet - 4 plug to 3 question.

[Pinewood]

Hi guys, I'd appreciate your help with this one... I have a workshop that I'm in and I'd like to convert an outlet that has a 4 plug outlet in it to three so I can plug in my welder. Problem is I'm a little perplexed as to what to do with the neutral wire when I go to the new three plug outlet and also because I have no ground wire.

This is the existing wiring into the 4 plug outlet.

And this is the back of the new 3 plug outlet. I know that red and black are hot and the white is neutral but what do I do with it now? It (white) shouldn't be connected to the ground(green) plug should it? The ground(green) plug is the one on the right.

Thanks for your help.

 

[pattenp]

First there should be a ground with a four wire outlet. The neutral would be wire nutted off and not used. The three prong should use the two hots and a ground. What is the NEMA # on the outlets?

 

[wyliesdiesels]

I was gonna say maybe there's metal conduit feeding the outlet but I don't think there's a bond between the ground screw and the yoke of the outlet. If its indeed a 3 wire feed to the outlet, tape the neutral wire with green tape on both ends. If the wire originates from your main panel(1st panel after the meter) then everything is good. If instead, the wire feeding this outlet comes from a subpanel, then the neutral wire needs to be moved from the neutral bar to the ground bar in the subpanel!

 

[Norcal]

Even if there is metal conduit feeding the receptacle, it's still wrong as that is not a self grounding device & I doubt there is one listed or made, it needs a grounding conductor..

 

[wyliesdiesels]

That's what I was trying to say but @ 12 in the morning, the words escaped me!

 

[Pinewood]

Thanks for the help guys.

PattenP: I would agree that there should be a ground wire but there isn't one... I'm not sure of the nema#, where would I find that?

Wyliesdiesels: This outlet is fed with metal conduit and the wire originates from the main panel and not a sub panel.

Maybe I need to open the panel and see what's going on at the other end?

 

[madosta]

Hmm, no green wire with the 4 plug is weird.

You can re-cord your welder with a 4 prong plug eliminating the neutral terminal from the plug, but you should probably fix your grounding issue first.

The conduit might be the ground, but that scares me.

 

[pattenp]

If the outlet box is metal and connected/grounded via the metal conduit then all you need to do is add a ground wire from the outlet to the metal outlet box. So take the new 3 wire socket and hook up the two hots and put a ground wire from the ground terminal of the socket to the box and wire nut the white as unused.

 

[wyliesdiesels]

Hmm, no green wire with the 4 plug is weird.

You can re-cord your welder with a 4 prong plug eliminating the neutral terminal from the plug, but you should probably fix your grounding issue first.

The conduit might be the ground, but that scares me.

How would re-cording the welder with a 4 prong eliminate the neutral? A 4 prong plug has a neutral. Also, why does using the conduit as a ground scare you? If the conduit is metal, then it is already grounded via the panel. Anything metallic(panel, conduit, jbox, etc.) should be bonded to and @ the same potential as ground in the breaker panel to prevent shock!

If the outlet box is metal and connected/grounded via the metal conduit then all you need to do is add a ground wire from the outlet to the metal outlet box. So take the new 3 wire socket and hook up the two hots and put a ground wire from the ground terminal of the socket to the box and wire nut the white as unused.

That's a better idea than i had- no need to mess with electrical tape! That's what happens when u try and think through this stuff @ midnight!

 

[pattenp]

How would re-cording the welder with a 4 prong eliminate the neutral? A 4 prong plug has a neutral. Also, why does using the conduit as a ground scare you? If the conduit is metal, then it is already grounded via the panel. Anything metallic(panel, conduit, jbox, etc.) should be bonded to and @ the same potential as ground in the breaker panel to prevent shock!



That's a better idea than i had- no need to mess with electrical tape! That's what happens when u try and think through this stuff @ midnight!

I believe code does not allow for the remarking of conductors 6 AWG or smaller as a EGC by using tape at the terminations. The grounding conductor has to be bare or the insulation has to be completely green.

 

[wyliesdiesels]

I believe code does not allow for the remarking of conductors 6 AWG or smaller as a EGC by using tape at the terminations. The grounding conductor has to be bare or the insulation has to be completely green.

Yeah, I think Norcal stated this in another thread. Is it just the remarking of a conductor to EGC that is not allowed or is the remarking of a conductor not allowed period(ie. from hot to neutral)? Do u happen to know the code section?

 

[madosta]

How would re-cording the welder with a 4 prong eliminate the neutral? A 4 prong plug has a neutral. Also, why does using the conduit as a ground scare you? If the conduit is metal, then it is already grounded via the panel. Anything metallic(panel, conduit, jbox, etc.) should be bonded to and @ the same potential as ground in the breaker panel to prevent shock!

Your cord to the welder is most likely 8/3 (as that's what mine is) you could cut the three prong stove plug off and put on a 4 prong plug, hooking both hots and ground up but since there is no neutral, you just leave that pin out of the cord plug all together. You would then need to bond the ground to your junction box unless it is electrically connected already through the screw flange.

Conduit is an excellent grounding conductor, but if it comes loose (by pure happenstance) and you need that least resistant path and you are standing in your awesome RedWings boots and it happens to be raining and well that's another story. My preference.

 

[pattenp]

Yeah, I think Norcal stated this in another thread. Is it just the remarking of a conductor to EGC that is not allowed or is the remarking of a conductor not allowed period(ie. from hot to neutral)? Do u happen to know the code section?

Ungrounded conductors can be remarked as provided in 210.5 (C).

EGC marking is 250.119

 

[jonahbones]

not familiar with 120v wiring so I am missing something here.
2 120v actives to give approx 220-240v and a neutral.
So I would initially think the 4 pin plug is for an earthed appliance and the three pin for a double insulated appliance ?
regardless of 3 or 4 pin your circuit is always active to neutral with ground or insulation for fault safety.
So how could you rewire the neutral as an earth?

 

[wyliesdiesels]

not familiar with 120v wiring so I am missing something here.
2 120v actives to give approx 220-240v and a neutral.
So I would initially think the 4 pin plug is for an earthed appliance and the three pin for a double insulated appliance ?
regardless of 3 or 4 pin your circuit is always active to neutral with ground or insulation for fault safety.
So how could you rewire the neutral as an earth?

Not quite sure what you're getting @ here but yes when you hookup 2 120v legs to a machine or appliance **** as an air compressor, dryer, water heater, etc., you get 240v! A neutral is used when you only need 120v. Neutral has nothing to do with getting 240v!

Every appliance should be grounded unless its an old dinosaur piece of ****. A 4 pin plug like the OP's is used when an appliance, machine, etc. needs 240v(2 hot legs) as well as 120v(between 1 hot leg and neutral). A 3 pin plug like the one the OP is using needs 2 hot legs and a ground because the machine does NOT need a neutral for 120v electricity.

A 240v circuit originating from a sub-panel will not be "active" to neutral because neutral and ground in a sub-panel should not be bonded together! You could rewire a neutral to ground(aka. what you're calling earth) by moving the neutral wire from the neutral bar in the sub-panel to the ground bar! But what you may be thinking of is how neutral and ground are bonded together in a service main! If you want to learn more i would suggest checking out a book about basic AC electrical!

 

[jonahbones]

electrical theory is fine different countries different systems. curious about 120 v as our supply is all 240v active to neutral appliances are more likely double insulated than earthed.
we step up to 415v 3 phase from 240volt 1 phase.
round here functional earth is neutral protective earth is earth hence MEN , multiple earth neutral supply. hence my reference to earth only carrying fault current
Always fun sorting out different terminology like pounds and feet to contemporary metric

 

[wyliesdiesels]

O I see. You're in England! Didn't know cause your location isn't specific!

 

[jonahbones]

Sorry have an annoying sense of humour, my location is a cryptic puzzle provided by location information and signature line....
Basic difference from memory is, you 120/240v split phase versus us 240v single phase thus giving you 240v across the phase potential,
dredging that up could be good for my long term memory

 

[wyliesdiesels]

Yes, we use split phase here! There is the occasional apartment building with 208Y/120 service, which gets distributed as single phase throughout the apartment units!