installing 50 amp.... 6-2NM vs 6-2NM-B

ProCharger · Feb 2, 2016

What is the difference between 6-2NM and 6-2NM-B. I have a buddy with a brand new roll of 6-2NM @ 125' he will sell me for $50. I will be running less than50' from my panel to my garage for running a welder and compressor. If this wire will work I will run 2 seperate circuits, no worries, I have an electrician that will do the install at the panel and the receptacle for $50 as long as I just need to run the wire for him. Will this wire work for this application? Thanks in advance.

wyliesdiesels · Feb 2, 2016

6-2 NM is NOS(new old stock) but code no longer allows its use because the conductors arent 90* c rated like NM-b conductors are. The b stands for 90* c.

Get some new wire.

Also what is the HP rating on the compressor?

pattenp · Feb 2, 2016

I assume the garage is attached to house.

ProCharger · Feb 2, 2016

ProCharger · Feb 2, 2016

wyliesdiesels said:
6-2 NM is NOS(new old stock) but code no longer allows its use because the conductors arent 90* c rated like NM-b conductors are. The b stands for 90* c.

Get some new wire.

Also what is the HP rating on the compressor?

Bummer, I was really hoping this wire would work. I was going to upgrade compressors once I was wired for it so no compressor yet. It would more than likely be a pretty standard 60 gallon like the HF 60.

wyliesdiesels · Feb 2, 2016

ProCharger said:
Bummer, I was really hoping this wire would work. I was going to upgrade compressors once I was wired for it so no compressor yet. It would more than likely be a pretty standard 60 gallon like the HF 60.

HP rating effects the wire size so before u wire up anything for a compressor u should settle on a HP size.

Over 3HP will require hardwiring unless u can find a receptacle and plug rated for the HP of the compressor. Standard NEMA receptacles and plugs are rated to about 3.5HP max....

Norcal · Feb 2, 2016

Agree with the above, code does not allow the use of NM cable rated under ninety degree C, the wire is scrap metal but with scrap prices in the toilet that won't bring as much as it would have in the past.

ProCharger · Feb 2, 2016

wyliesdiesels said:
HP rating effects the wire size so before u wire up anything for a compressor u should settle on a HP size.

Over 3HP will require hardwiring unless u can find a receptacle and plug rated for the HP of the compressor. Standard NEMA receptacles and plugs are rated to about 3.5HP max....

Looks like it would be a 5hp motor. My plan was to run both circuits to NEMA 6-50r's and then wire the compressor to a NEMA 6-50p. Would that not work? That way I can run a plasma cutter and the welder at the same time. When I get home I can measure the run to get closer on length. Plasmas a Hypertherm pm30 air.

Thanks for the info. This thread has been a huge help.

wyliesdiesels · Feb 2, 2016

Norcal said:
Agree with the above, code does not allow the use of NM cable rated under ninety degree C, the wire is scrap metal but with scrap prices in the toilet that won't bring as much as it would have in the past.

no kidding!!! :toilet:

My neighbor gave me his old rusted out water that he recently replaced and i took it down to the scrap yard. It weighed about 200lbs.

When i checked out after reweighing the clerk handed me a dollar.

I blinked

several times and did a double take. Went back and asked the weighmaster. He said scrap prices are WAAYYY down. :shocking:

I got paid .005 cents/lb. use to get .04 cents/lb a few years ago when i did water heaters. For 4 water heaters i would get $30-$40....not anymore... :sad:

wyliesdiesels · Feb 2, 2016

ProCharger said:
Looks like it would be a 5hp motor. My plan was to run both circuits to NEMA 6-50r's and then wire the compressor to a NEMA 6-50p. Would that not work? That way I can run a plasma cutter and the welder at the same time. When I get home I can measure the run to get closer on length. Plasmas a Hypertherm pm30 air.

Thanks for the info. This thread has been a huge help.

Unless its rated for 5HP or more(it wont be) then NO! It needs to be hardwired.

And how would u run both machines at the same time? Will there be more than one person working at the same time?

And u will need the compressor for the plasma. So do u plan on running all 3 at the same time?

Best thing to do is give the compressor its own circuit, hardwired!

ProCharger · Feb 2, 2016

30xp air has its own compressed air, latest new thing from hypertherm. As far as both machines at once I just meant without having to unplug one and plug the other back in.

What wire size would be needed for a 50 foot run to a hardwired compressor in the 5hp range. Compressor I was looking at is rated for 22 amps.

Edit: Just measured, 35 feet up from bottom of panel, over, and up into garage depending on height from the floor. Figure 40 feet to be safe.

wyliesdiesels · Feb 2, 2016

ProCharger said:
30xp air has its own compressed air, latest new thing from hypertherm. As far as both machines at once I just meant without having to unplug one and plug the other back in.

What wire size would be needed for a 50 foot run to a hardwired compressor in the 5hp range. Compressor I was looking at is rated for 22 amps.

Edit: Just measured, 35 feet up from bottom of panel, over, and up into garage depending on height from the floor. Figure 40 feet to be safe.

Thats a short run so VD(voltage drop) doesnt come into play.

5HP requires 35a rated wire(28FLC * 125%= 35a)

So u need #10 THHN/THWN in pipe or #8/2 NM-b

If the compressor is out of sight and more than 50' from the panel a local disconnect is required.

Breaker can be max 250% of FLC. But a 30a may work. If not try a 40a.

Charles (in GA) · Feb 2, 2016

wyliesdiesels said:
If the compressor is out of sight and more than 50' from the panel a local disconnect is required

If the compressor is out of sight of the breaker panel OR is more than 50 ft from the panel (even if visible from the panel) then the local disconnect is needed.

Its not AND.......... its OR......... makes a HUGE difference.

Charles

wyliesdiesels · Feb 2, 2016

Yeah i always seem to mees that one up! My fingers type faster than my brain.

sberry · Feb 2, 2016

I would pay scrap price and run the wire, the comp or the welder will never know the difference. Its a size or more bigger than it needs to be. 50$ for 125 ft, this doesn't sound like its getting inspected wouldn't lose a moments sleep about 60 or 90 rating especially if it was going in a little older house where it didn't stand out.

wyliesdiesels · Feb 2, 2016

sberry said:
I would pay scrap price and run the wire, the comp or the welder will never know the difference. Its a size or more bigger than it needs to be. 50$ for 125 ft, this doesn't sound like its getting inspected wouldn't lose a moments sleep about 60 or 90 rating especially if it was going in a little older house where it didn't stand out.

So because its not being inspected justifies doing it wrong??

DieselPills · Feb 2, 2016

wyliesdiesels said:
So because its not being inspected justifies doing it wrong??

Just because it doesn't exactly meet code for some stupid pointless reason does not make it "wrong".

If the cable is not expected to exceed the temperature rating of the wire you want to use (for example is oversized for the load), nothing is wrong. It was "safe" a few years ago. If your wires are hitting 90C they are probably overloaded anyway.

bczygan · Feb 2, 2016

wyliesdiesels said:
So because its not being inspected justifies doing it wrong??

If it works, it works...

I know it's wrong, and leaves something non standard for someone else to worry about down the line.

But frankly, how much non standard stuff have you seen. How much grandfathered, but now not standard things are out there? Until it was recently knocked down, my grandfathers house had working knob and tube.

It is nice to know the right way though. And I really appreciate the few of you, who give us that, here on GJ.

Bill

sberry · Feb 2, 2016

I realize that this doesnt meet the current letter and wouldnt do it in a new build but this pretty tame in the world of code violations. Obviously you do it at your own risk but it's pretty minor.

wyliesdiesels · Feb 2, 2016

Sure its minor out of all the non code permitted work we see.

However, as an electrician(speaking for myself and the others on here) we cant recommend anything other than what the code is.

If u dont want to follow code then by all means...

nadogail · Feb 2, 2016

IIRC, isn't 60 degrees Celsius equal to 140 Fahrenheit?

What, other than the shop burning, would make the NM cable that hot?

sberry · Feb 3, 2016

I agree if I was putting this in for hire it would be another matter. if it was mine would do it provided it was in good condition or if it was something a bud had and needed help with in his garage.

Norcal · Feb 3, 2016

Using 30-35 year old cable IMHO, is not a wise move. Just a little food for thought. I am not advocating ripping out all the old 60° C rated cable installed, but installing stuff sitting around all these years just ain't right.

DieselPills · Feb 3, 2016

wyliesdiesels said:
However, as an electrician(speaking for myself and the others on here) we cant recommend anything other than what the code is.

On this board, nobody is your customer, and nobody is an electrician. (we've never seen your credentials and never will) Surely, you can use your vast knowledge as an electrician to help when people need to bend the rules a little bit.... :lol_hitti

Just get it out of your head that if it isn't code then it is "wrong". That is NOT true.

Norcal said:
I am not advocating ripping out all the old 60° C rated cable installed, but installing stuff sitting around all these years just ain't right.

I agree, 50' of 6ga isn't that expensive. Might be cheapest to get a 500' spool of THHN, even if you don't need that much. All the suppliers love to **** you on <500' rolls.

sberry · Feb 3, 2016

Norcal is correct, it is wrong and for good reason. But, now the focus is on number 6 wire which the op doesn't need, that was the available wire.

sberry · Feb 3, 2016

Just get it out of your head that if it isn't code then it is "wrong". That is NOT true.

It is absolutely true. That doesn't mean it wont work, there is a difference. I am really getting older and time is flying, how long has it been obsolete?
I just rewired whole house to rid it of old wire. 35 years is a good portion of its service life.

sberry · Feb 3, 2016

There may be a time and place for using something like that but hidden in a new build or remodel isn't it.

sberry · Feb 3, 2016

People get on a Harley and ride down to the store for a pack of smokes and this is deemable risk by an insurance companies. Ha. No helmet.
I had some reservation about saying I would use it but that's what generates a little interest. As Ii mention in other threads I have come a long way over the years to change my original theory that me and the boys had when we were full of it that we could at least certainly invent our way around such nonsense and when I look around at old handyman that followed that philosophy thy learned once the wrong way and that was the end of it.
I worked on this principle in the water heater thread, he wants to research enough to ask about tearing something apart and improving it, the thing is a standard. The guy could serve it with a wire undersized and never have a fault for decades or pinch a wire more likely trying to "upgrade" something that isn't broke and been factory assembled.
Installation error will trump wire here especially in the relative short term provided the coating isnt already crumbling etc.
Its risk in another 30 years would go up but buildings are insured daily with lots of it. In a home garage with separate outlets for tools this wire will never see 1/2 load for than 5 minutes at a time very intermittently.

ProCharger · Feb 3, 2016

The wire is dated on it's cover November 7, 2007. BTW I am an idiot. The outside wrap has no mention of NM-B but if I read the wire cover itself it does say NM-B.

Not to stir the pot or anything but can this same wire/size be used for a 50 amp circuit with a 6-50R in the same length run to supply a welder with power?

pattenp · Feb 3, 2016

The #6 NM-b pictured can be used for a 50A circuit using a 6-50R for the length you need..

sberry · Feb 3, 2016

It would make a super cable for welder circuit.

wyliesdiesels · Feb 3, 2016

DieselPills said:
On this board, nobody is your customer, and nobody is an electrician. (we've never seen your credentials and never will) Surely, you can use your vast knowledge as an electrician to help when people need to bend the rules a little bit....

Just get it out of your head that if it isn't code then it is "wrong". That is NOT true.

I agree, 50' of 6ga isn't that expensive. Might be cheapest to get a 500' spool of THHN, even if you don't need that much. All the suppliers love to **** you on <500' rolls.

So whats the point of code books then?

ProCharger said:
The wire is dated on it's cover November 7, 2007. BTW I am an idiot. The outside wrap has no mention of NM-B but if I read the wire cover itself it does say NM-B.

Not to stir the pot or anything but can this same wire/size be used for a 50 amp circuit with a 6-50R in the same length run to supply a welder with power?

looks like youre good to go :thumbup:

sberry · Feb 3, 2016

We can all sleep a bit easier tonight.

DieselPills · Feb 4, 2016

wyliesdiesels said:
So whats the point of code books then?

Mostly over legislated ******** and a way for the government to get their cut every time somebody does any electrical work.

Too many people think the code book is a book about "the best and only way to do AC wiring". That is not what it is at all. It is simply the opinion of certain people in the United States that certain things need to be done a certain way. There is always more than one way to do things, and just because it isn't prescribed exactly that way in the NEC does NOT make it in any way wrong or unsafe.

Different parts of the country use different revisions of the NEC. Does that mean what they do in one state becomes unsafe if you do it in another state where they have recently changed the code to not allow that? No, not really.

There are SO MANY things in the NEC that are only there because of fat walleted lobbyists and other rules that just plain don't make sense at all. It's just like the US tax code, or EPA restrictions, good intent, but full of problems.

Yes, the NEC makes a good general guideline, but no, it's word is not god, and it's not the only safe way to do things. An electrician who cannot see outside the NEC cannot think for himself.

7thDimension · Feb 4, 2016

DieselPills said:
Mostly over legislated ******** and a way for the government to get their cut every time somebody does any electrical work.

Too many people think the code book is a book about "the best and only way to do AC wiring". That is not what it is at all. It is simply the opinion of certain people in the United States that certain things need to be done a certain way. There is always more than one way to do things, and just because it isn't prescribed exactly that way in the NEC does NOT make it in any way wrong or unsafe.

Different parts of the country use different revisions of the NEC. Does that mean what they do in one state becomes unsafe if you do it in another state where they have recently changed the code to not allow that? No, not really.

There are SO MANY things in the NEC that are only there because of fat walleted lobbyists and other rules that just plain don't make sense at all. It's just like the US tax code, or EPA restrictions, good intent, but full of problems.

Yes, the NEC makes a good general guideline, but no, it's word is not god, and it's not the only safe way to do things. An electrician who cannot see outside the NEC cannot think for himself.

A bunch of people will probably throw a fit over that, but I agree entirely.

sberry · Feb 4, 2016

Amateur uneducated opinion.

sberry · Feb 4, 2016

What makes even more comical is the posters know absolutely nothing about it but know this. ha
As a matter of fact I took a service call the other day where the job was wired by a guy with this exact thouht,, the cause of the problem was one of those dumb minor code violations, this guy knows more about this kind of thing than most people do too.

sberry · Feb 4, 2016

Yes, they want it done the same way,, kind of like everyone drives on the same side of the road.
We see the results all the time of people do it how they feel like it or how they think it should be,, hence the need for the book.

sberry · Feb 4, 2016

Yes, the NEC makes a good general guideline, but no, it's word is not god, and it's not the only safe way to do things. An electrician who cannot see outside the NEC cannot think for himself.

They are not general guidelines. They are specific rules.
We got lots that see outside, usually outside wondering why they do not get a paycyheck. They are not stupid but just smart enough to believe they are smarter than everyone else and most of their code experience has been from a blight enforcement officer. I know half a dozen guys think like this and almost to the T every one is a compulsive junk hoarder.
They are about impossible to train and a guy really cant hire them.

installing 50 amp.... 6-2NM vs 6-2NM-B

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