NEMA 650R from a SUBPANEL

[Clik]

I'm installing an Outlet for my welders and plasma cutter NEMA 6-50R.

Just to clarify: THIS IS FED BY A SUB PANEL.

I'm not clear on Neutral vs Ground in a Sub Panel.

My plan was Black Wire to one side of the double pole 40 Amp Breaker,

White Wire (marked Black with tape) to other side of double pole Breaker,

Green Wire to Ground Bus Bar.

I don't need anything to Neutral? I only need 3 wires right?

 

[pattenp]

Right, just need the 2 hots and ground. No neutral is needed. Also the neutral bar should be isolated (not grounded) in a sub-panel.

 

[Clik]

Oh, and I still need to pig tail ground the metal outlet box, right?

 

[pattenp]

Oh, and I still need to pig tail ground the metal outlet box, right?

Yes, if you're using a metal box.

 

[Clik]

Thanks. I appreciate the advice.

 

[Clik]

Hey PattenP, I'm getting different and conflicting info here. This is from Miller's site. read the last line:

"I got to jump in on the neutral wire discussion here and put my electrical engineering degree to some good use for a change.

Both Line 1 (L1) and Line 2 (L2) are 120 volts AC with respect to the neutral bar. However, they are 180 degrees out of phase, so if you put a load between L1 and L2, you get 240 volts AC. Most welders that run off 240 volts AC use a three conductor plug. The load is connected to L1 and L2. The chassis is connected to ground. The neutral in this case is not used.

Ground is not to be confused with the neutral connection. They serve separate functions even though they are bonded (connected together) at most breaker panels. Most new breaker installations have an "isolated ground bar" where the ground wires are connected separate from the neutral bar even though they both go to ground.

There are some plugs - like the 220V/50A plug the Bobcat and TB that have four connections (L1, L2, Neutral and Ground). That plug is intended for applications where your load needs both 240V and 120V circuits. I don't have my charts in front of me or I'd give the NEMA numbers for these outlets/plugs.

The reason the neutral and ground need separate conductors is what confuses most folks. Because the neutral is grounded from the power company, there can be a slight voltage difference between it and the local earth ground. If that voltage potential gets large enough, it can be dangerous. This is why the chassis of appliances needs a ground wire that is separate from the neutral.

When should you use four wires and when should you use three? It depends on the plug your welder requires. If you use the three prong plug, you need three. If you use the 4 prong plug, you need four. Most welders use a three prong plug.

A good example of a four prong plug is a 50 amp RV connection. The RV may or may not have any 220 volt appliances, but it utilizes both of the 120 volt lines. The other major use for a four wire application is a sub-panel. It needs both the neutral and ground wires to be separated in order to be safe".

 

[pattenp]

What are you confused about? The sub-panel is fed with a four wire feed, two hots, 1 neutral and 1 ground. The circuit from the sub-panel for the welder outlet only needs 2 hots and a ground to provide 240V. The neutral is only needed if 120V is needed and the welder should not need 120V. The neutral to the sub-panel is so the panel can provide 120V circuits via single pole breakers. Or provide 120V/240V such as a stove may need.

 

[Nostraquedeo]

What is the conflicting info? The other guy just elaborated and talked about an RV receptacle that might need a neutral for 120 volt loads. Most welders just need two conductors(L1 and L2) with a ground. THREE wires total. You can run a neutral to the box and then wire nut it for future use, but most likely not needed for your welder. Your welder manual or the welder plug should list the NEMA configuration required.

 

[Clik]

The last line in what was written on the Miller site is what had me confused: "The other major use for a four wire application is a sub-panel. It needs both the neutral and ground wires to be separated in order to be safe".

 

[pattenp]

The last line in what was written on the Miller site is what had me confused: "The other major use for a four wire application is a sub-panel. It needs both the neutral and ground wires to be separated in order to be safe".

Are you clear now? This part means that the neutral bar is to be isolated/insulated from the ground bar in a sub-panel. The only panel that the neutrals and grounds can land on the same bar or bars that are bonded together is in the first main service panel.

 

[Clik]

I took what the guy on the Miller site was saying to mean:

Black to one terminal on the double pole breaker, Red to the other pole on the double pole breaker, White to the neutral bar and bare ground to the ground bar which left me to assume that the recepticle end of the bare ground wire would be attached to the metal box only. ?????????????????

 

[Clik]

The sub-panel's Neutral and Ground do appear to be seperate.

 

[pattenp]

I took what the guy on the Miller site was saying to mean:

Black to one terminal on the double pole breaker, Red to the other pole on the double pole breaker, White to the neutral bar and bare ground to the ground bar which left me to assume that the recepticle end of the bare ground wire would be attached to the metal box only. ?????????????????

Oh no.... I see what you were thinking. But to make sure you understand you only need three wires to the outlet box for the welder. What you originally posted is correct if using NM (Romex) wire. Black, White remarked as Red or Black, and bare ground. The ground goes to metal box and pig tailed to the outlet ground. As said by another poster you can run the third wire for a neutral and wirenut it off for future use if needed to get 120V/240V at that box.

 

[Clik]

OK, Many, many thanks for the help.

I had tried youtube and some other sites and it's amazing how many people post as "experts" and don't even know the names of the parts they're working with. "The thingy". Geeeez!

 

[pattenp]

OK, Many, many thanks for the help.

I had tried youtube and some other sites and it's amazing how many people post as "experts" and don't even know the names of the parts they're working with. "The thingy". Geeeez!

Yep, that's the down side of trying to get this type of info from the internet. You have to wade through the ****. I think people honestly think they know what they're talking about and try to give helpful info, but when it comes to electrical you really need to do your homework to make sure you're getting correct information.