Installing 240V 50Amp

[Dugan]

I'm prob going to be using 8 Gauge wire. I was going to install atleast two receptacles one by the "Future" lift and one by the door.

I know stranded is better/easier to move/larger than its solid counterpart, but is putting stranded into breaker panel a PIA? Would it be better to run a small solid down to a junction box below the panel and run the stranded from there? *Ive only ever worked with Solid in houses*

Im an electrical engineer.. Go ahead flame.. I have experience with wiring homes/cars etc but its the small things I'm unsure of. So I thought id post to get your ideas.

Also, the welder and Plasma only draw about ~30A and have the 2 spade 1 round 30A plug, but its easier to find the 50A 4 prong plugs around here. Lowes is always out of the 30A for some reason. So i Was going to install the 50 with the extra outlet incase I have something in the future that can use it to have a versatile outlet. Any problems running the higher breaker? Or should I keep it at 30A for the overload protection.

 

[pattenp]

I'm not sure if I'm following you on what receptacles you plan on using, such as mixing 30A and 50A on same circuit. If the circuit is 50A then the outlets can be no smaller than 50A. If the wire is #8 it needs to be THHN @ 75 degree C., NM (Romex) needs to be #6 for 50A because it's 60 degree C. Also some jurisdictions do not allow multiple outlets on circuits larger than 20A.




*

 

[LG63]

Also, the welder and Plasma only draw about ~30A and have the 2 spade 1 round 30A plug, but its easier to find the 50A 4 prong plugs around here. Lowes is always out of the 30A for some reason. So i Was going to install the 50 with the extra outlet incase I have something in the future that can use it to have a versatile outlet. Any problems running the higher breaker? Or should I keep it at 30A for the overload protection.

You might consider twist locks. 250V/30A twist lock plugs and receps are common and relatively inexpensive on Ebay.

 

[soapii]

I put two 50 amp circuits off my subpanel for a welder. I used 8/3 NM-B (stranded) for both. I also used a duplex box for each single 50A outlet to give me extra room for wire routing.

Stranded is easier to manipulate than solid.

--Joe

 

[soapii]

NM (Romex) needs to be #6 for 50A because it's 60 degree C.

http://www.homedepot.com/p/Southwir...G-Wire-63949202/202316278?N=bm7v#.Uo4q8G3yUdI

PRODUCT OVERVIEW

Wire residential indoor branch circuits for outlets, switches and other loads with Southwire Romex SIMpull Type NM-B Cable. SlikQuik jacket allows for 50% reduction in pulling force for easier installation. NM has a heat capacity of 90* C and a usage rating of up to 600 volts.

--Joe

 

[pattenp]

I don't mean to pop your bubble, but #8 NM-b is to be used for no more than 40 amps. The 90C is to be used for derating purposes. NEC limits NM to 60C. 2011 NEC 334.80

Edit: If you don't believe me, here's the chart from Southwire. See page 2 ampacity for #8 and foot note.

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet6

I put two 50 amp circuits off my subpanel for a welder. I used 8/3 NM-B (stranded) for both. I also used a duplex box for each single 50A outlet to give me extra room for wire routing.

Stranded is easier to manipulate than solid.

--Joe

 

[pattenp]

Dugan, I'd stick with the regular (non twistlock) 6-50R and 6-50P for the plugs and outlets for the plasma and welder. Those are the common ones used. You can do a 30 amp circuit with the 50A plugs, but just not a 50 amp circuit with 30A plugs. My suggestion is to do the circuit as 50A with the 50A plug and outlet.

 

[Dugan]

I found a NEMA plug diagram. Appears both the outlets I was picturing are both 50AMP. NEMA 6-50 (3 Prong) vs. NEMA 14-50 (4 prong).Reference

My mistake. Im going to run the 4 Prong for the versatility incase someone brings in something with 4 prongs.

Would a 50A breaker be a no-no running devices that could be run on 30A breaker?

Seeing that the wiring will be ran behind the Poles in the Pole barn would it just be cheaper to run 8/3 NM-B?

 

[Charles (in GA)]

I found a NEMA plug diagram. Appears both the outlets I was picturing are both 50AMP. NEMA 6-50 (3 Prong) vs. NEMA 14-50 (4 prong).Reference

My mistake. Im going to run the 4 Prong for the versatility incase someone brings in something with 4 prongs.

Would a 50A breaker be a no-no running devices that could be run on 30A breaker?

Seeing that the wiring will be ran behind the Poles in the Pole barn would it just be cheaper to run 8/3 NM-B?

As already noted, the 8/3 NM-B isn't suitable for 50 amp, you would need to go to #6 in NM for 50 amp.

Note that if you use 4 prong, you use a neutral, two hots and a ground.... while with three prongs, you use a ground and two hots.... NO neutral, cheaper but less flexibility in the future. I always carry a neutral to a distant 240v receptacle, even if it is not needed.

Charles

 

[pattenp]

The breaker protects the circuit, not the device. It's okay to run the welder on a 50A circuit even if it only requires a 30A circuit. Think of a table lamp that only requires 1 amp and has a skinny 16 gauge cord that gets plugged into a 20A circuit.

...........
Would a 50A breaker be a no-no running devices that could be run on 30A breaker?

.........

 

[Charles (in GA)]

In the UK the plugs on things such as lamp cords apparently have fuses install in the plug, so the cord is properly protected also. Actually a neat idea.

Charles

 

[soapii]

I don't mean to pop your bubble, but #8 NM-b is to be used for no more than 40 amps. The 90C is to be used for derating purposes. NEC limits NM to 60C. 2011 NEC 334.80

Edit: If you don't believe me, here's the chart from Southwire. See page 2 ampacity for #8 and foot note.

http://www.southwire.com/ProductCatalog/XTEInterfaceServlet?contentKey=prodcatsheet6

No bubble to be popped, I'm not a certified electrician. Thanks for the info.

--Joe

 

[pattenp]

There was a problem in the Home Depots and Lowe's at one time where Southwire had supplied charts that listed the 90C ampacity rating of their NM wire which led DIY'ers to get the wrong size wire. The wire chart supplied by Southwire now list the ampacity as required by the NEC. On a couple occasions I pointed it out to the store manager at our local Lowe's about the chart being wrong and they just ignored me.

No bubble to be popped, I'm not a certified electrician. Thanks for the info.

--Joe

 

[Dugan]

There was a problem in the Home Depots and Lowe's at one time where Southwire had supplied charts that listed the 90C ampacity rating of their NM wire which led DIY'ers to get the wrong size wire. The wire chart supplied by Southwire now list the ampacity as required by the NEC. On a couple occasions I pointed it out to the store manager at our local Lowe's about the chart being wrong and they just ignored me.

Yea i was reading that chart... With all the "fluff" they add to it, pictures of happy familes etc. I didnt trust it. Id rather look it up or ask where I know I can get real answers to back up my research to be safe.

Thanks for all the info Ill have to go check out and see if i can get some 6Ga. If it ends up being a crazy amount of money different I might just run a 30A circuit. But do it once and never have an issue I guess. If running a welder/plasma is gonna heat up the lines it might be worth it to have the extra buffer of heat protection.

 

[Dugan]

In the UK the plugs on things such as lamp cords apparently have fuses install in the plug, so the cord is properly protected also. Actually a neat idea.

Charles

They also do this in christmas lights... Ask me how i know

 

[dasmotiu]

For a Nema 14/50 receptacle in my garage for my wife's Tesla Model S I pulled 3 x 8gage THHN and a 10gage ground through surface-mounted 3/4" conduit and it was the easiest wiring job I ever did, in my opinion way easier than pulling Romex. But then my main panel is in my workshop adjacent to the garage and so the run of cable is only 65 feet. And the ampacity rules say 8gage is acceptable with THHN. It does get warm ... but not hot.

 

[C96]

Im an electrical engineer..

Allot of very basic questions being asked here for an electrical engineer, hmm, interesting.

 

[laser3kw]

Allot of very basic questions being asked here for an electrical engineer, hmm, interesting.

never hurts to expand your knowledge.

 

[Norcal]

In the UK the plugs on things such as lamp cords apparently have fuses install in the plug, so the cord is properly protected also. Actually a neat idea.

Charles

They are plugged into a 32A ring circuit,BTW, hence the fused plug.

 

[sberry]

The welder plugged in to this doesn't need 50A and you do not need 3 conductor, only 2 and ground and use 6-50-P so it isn't bastardized. Thats what comes with welders. I added a recept to my hoist for welder, same wire.