Running 220, have a question re: welder current draw

[TT_Vert]

After looking at the attached specs it appears that a 30A breaker would be acceptable. Am I interpreting this correct? Do I need additional overhead here? If that is the case I assume 10AWG would be acceptable but my question is, at what distance do I generate enough additional resistance to force me to step up in wire gauge? I already have one 220 outlet which is going to be for my compression and i believe I have extra room in my sub panel to add more breakers. I am going to trace my wiring (Finished walls/ceiling) and see if I may be able to just convert one of the 110V circuits to 220 and utilize its conduit and well exits as I'm not going to rip out drywall to run wire (NO attic). If I do, would i be better suited putting in a 50A breaker and running 6AWG and having all of my 220 devices (Minus compressor which will remain on it's own dedicated circuit w/ my lifts) for everything on the same circuit. The only things I can see running 220 would be a plasma cutter or a welder as of now. I would not be using either of them at the same time however. And given the ceilings in the garage are 12' tall, the depth of the garage is 22' I'd be at about 52' from the electrical panel to the closest wall outlet. About 80' for the furthest. OR the easy way, I just put one 220 outlet right below the electrical panel and run an extension cord to the device I'm using.

What do you guys think is best?


Dave

 

[sberry]

What model is this? There will be wire size in the manual but they can be confusing. Actually that machine can use 14 at 70 ft with a 30,,, so,,, a 10 will be way suffecient and the length not an issue. A comp should be on its own circuit.
In theory 2 welders, a plasma of this class could run from a 50 depending on wire methods. Many 50A machines actually allow a 12 wire, over 80 ft but,,,,,, no one thinks that is a great idea and performance droops some. Once it is 10 wire it's pretty much moot, but this is one outlet on a circuit with under sized wire, the minimum for 14 and 12 on these types of circuits are for single circuit in pipe, cable and cord require a size larger.

 

[wyliesdiesels]

Welder circuits have special wiring requirements and exceptions.

Its all based on input current and duty cycle....

Make and model of welder would be helpful....

looks like 100% duty cycle is possible so should go with full size wire.

 

[TT_Vert]

I figured those electrical specs from welder would be enough but it's a HF Vulcan omnipro 220

https://manuals.harborfreight.com/manuals/63000-63999/63621.pdf

 

[s14kev]

I went through this a few weeks ago. Most of my welders use a NEMA 6-50P plug. This is a 50A plug. If you are going to install a 6-50P outlet, it means any piece of equipment with a 6-50P plug should be able to be plugged into it. As such I'm running a 50A breaker and 6-2 wire. This is overkill for my little Miller TIG but since the outlet dictates 50A, it should be possible for any future equipment. The slight extra expense of 6GA wire was worth it to not have to rip out drywall and upgrade later.

IRC does not allow multioutlet circuits above 20A. Technically you need a separate breaker for each 220V outlet. I went against the IRC by having 2 outlets on the same breaker. I figure if I leave, I'll remove the middle outlet, splice the wires and put a blanking plate over the electrical box.

 

[TT_Vert]

Yeah if i have to run 6AWG I will. The issue is I hope to use existing conduit and I'm not sure i have room for three 6AWG wires.

 

[ez-duzit]

...If you are going to install a 6-50P outlet, it means any piece of equipment with a 6-50P plug should be able to be plugged into it. As such I'm running a 50A breaker...

This. Cheap out on the welder, if you must. But not on the wiring.

I have a 50-amp breaker for mine as well.

 

[TT_Vert]

Ok so it appears I cannot get 3 6AWG through the 1/2" conduit. So I guess my question is, am I mis-interpreting the specs on this welder in that it needs a 30A breaker?

Dave

 

[Bert_]

Yeah if i have to run 6AWG I will. The issue is I hope to use existing conduit and I'm not sure i have room for three 6AWG wires.

If you use THHN in conduit then #8 is good for 50A. Most 50A outlets and breakers are rated 75*C so you can use that column for sizing.

The ground can be #10 for circuits up to 60 amps.

2 #8's and a #10 can be crammed into 1/2" conduit if you really have to.

 

[brewchief]

A plug below the panel can be pretty easy, I bought a 50' #8 cord with nice molded plugs a couple years ago for 100$ shipped to my door.


Sent from my XT1254 using Tapatalk

 

[TT_Vert]

So I suppose what I could do is put a 6-50P under the panel and use an extension cord. I just need to see if I can get the conduit up in through the hole I cut for the plug and box but I doubt it'll be high enough to actually manage that without the ground interfering..

My only issue with this method is the garage is very large and on occasion I may truck my stuff outside to do work w/ my mobile bench when I don't want to make a huge mess inside the garage.

Dave

 

[sberry]

You can use 10 for that machine even with a 50,,, but you can use a 30 too. The only reason for a bigger wire is some specify machines and most that need it to not come factory plug. The fear of needing a bigger wire is wayyyyyy overblown, if this was a problem the code would have been changed long ago. Compressors need to be motor rated for the plug ins, it couldnt feed a 5 anyway, only cord and plug welders that need 8 are 250 migs, most ovens or ranges are 4 wire,,, and ,,,, the machine you spec calls for a 14,,, but,,,,,,, you can run a 6 if you want.

 

[sberry]

Other equiment doesn't "come" with a 6 50 P.

 

[TT_Vert]

You can use 10 for that machine even with a 50,,, but you can use a 30 too. The only reason for a bigger wire is some specify machines and most that need it to not come factory plug. The fear of needing a bigger wire is wayyyyyy overblown, if this was a problem the code would have been changed long ago. Compressors need to be motor rated for the plug ins, it would feed a 5 anyway, only cord and plug welders that need 8 are 250 migs, most ovens or ranges are 4 wire,,, and ,,,, the machine you spec calls for a 14,,, but,,,,,,, you can run a 6 if you want.

Ok I'm confused. Do you mean 50A breaker or 6-50 plug? I assume the plug as running 10AWG w/a 50A breaker is a recipe for disaster. This is a 120/240 mig/tig welder BTW. Am I correct in interpreting the specs on this as attached above as pulling a max of 25.5A @ 220V?

Thanks,

Dave

 

[sberry]

That machine can use a 50A breaker on 12 wire, single circuit in pipe.
What machine is it? I am not familiar with all the combination models. A 211 Miller requires a 14 wire, this combo may be 12, you should look at the manual.
What you should do may be different than what's legal. Run 10 with a 30, it makes a tailored circuit for it. I really post the difference due to the obvious misunderstanding about these circuits.
The machines are duty cycle limited. A 225AC pulls 48,, or can pull it, comes with a 12 cord, 50A end, can be wired with 12.

 

[TT_Vert]

That machine can use a 50A breaker on 12 wire, single circuit in pipe.
What machine is it? I am not familiar with all the combination models. A 211 Miller requires a 14 wire, this combo may be 12, you should look at the manual.
What you should do may be different than what's legal. Run 10 with a 30, it makes a tailored circuit for it. I really post the difference due to the obvious misunderstanding about these circuits.
The machines are duty cycle limited. A 225AC pulls 48,, or can pull it, comes with a 12 cord, 50A end, can be wired with 12.

Ok so I understand, while this machine may be able to safely use a 50A breaker on a 12AWG wire wouldn't that potentially cause a fire drawing 50A on a 12AWG wire? I may not plug anything else into that outlet but if a new homeowner ever comes in and sees a 50A breaker they are going to assume it'll sustain 50A w/o melting.

That welder is a harbor freight vulcan omnimax 220. I did post excepts from the manual which I thought were pertinent. How can I tell what is required if all it says in one spot is max current 25.5A @200A for mig and then in another it says plug into a 20A receptacle? Do you see my confusion?

Dave

 

[sreeb]

I would add a sub-panel in the garage. 6AWG/50A feeding panel should be enough for a one man shop.

 

[TT_Vert]

Dumb question but why add a sub panel? The sub panel would have go to into the same joist unless I want to do significant drywall work to run conduit through studs. If my goal is just one 6awg feed in the same joist I could do that and have the space to do so. Pic of said box attached for reference. What I'm leaning towards is putting a 50A in and a 6-50 outlet directly below the box in 6-3 romex and an old work box for the welder and other device. Then just using an extension cord around the garage. The cord will have to be a good 50' long however. And then my 220 compressor is another issue. It needs a 40A breaker and currently has a 20A over there w/ 12AWG. I'm HOPING I can feed 2 8AWG into the 1/2" conduit that is shared w/ a few outlet circuits going that way and then put a 50A Breaker in for that too.

thanks much,
Dave

 

[pattenp]

For 240V only using a 6-50 outlet, you need 6-2 NM, not 6-3 NM. You may be over filling the 1/2" conduit by adding 2 #8's depending on how many 12's are already in it.

 

[sreeb]

Dumb question but why add a sub panel? The sub panel would have go to into the same joist unless I want to do significant drywall work to run conduit through studs. If my goal is just one 6awg feed in the same joist I could do that and have the space to do so. Pic of said box attached for reference. What I'm leaning towards is putting a 50A in and a 6-50 outlet directly below the box in 6-3 romex and an old work box for the welder and other device. Then just using an extension cord around the garage. The cord will have to be a good 50' long however. And then my 220 compressor is another issue. It needs a 40A breaker and currently has a 20A over there w/ 12AWG. I'm HOPING I can feed 2 8AWG into the 1/2" conduit that is shared w/ a few outlet circuits going that way and then put a 50A Breaker in for that too.

thanks much,
Dave

Maybe I misunderstood your situation.

I thought you were describing a situation where you needed to route individual circuits from a panel that is remote from the garage. In that case, it will be easier in the long run to install a sub panel in the garage and make garage additions from there.

If your panel is already in the garage then you are good with the existing panel. That panel isn't even close to full assuming that it allows double density breakers.

 

[sberry]

A 5 hp comp requires 10 in pipe, that will go 1/2 easy. Your welder will work 10 in pipe. 40A for the comp and breakers from 30 to 50 or the welder. I have a convenience outlet on panels around the shop, various wire on them as it was free at the time but at the welder home I have 1 with a 6 wire 50 for the heavy mig, 2 of then 10-50 for plasma and a DC stick and 2 of them 10-30 for compact migs.
I have a welder outlet on the hoist wire, a 10-30 so I can plug mig there.
I have installed a couple few for buds using old work boxes below the panel. The welder could use a 10 cable, depending on model the comp may need an 8 in cable to meet the code.

 

[TT_Vert]

For 240V only using a 6-50 outlet, you need 6-2 NM, not 6-3 NM. You may be over filling the 1/2" conduit by adding 2 #8's depending on how many 12's are already in it.

I have 3 12 AWG wires in there already for the 110 outlets. I found an online calculator and w/ two 8awg and the 3 12AWG wires and it said it was the equivalent of a 3AWG wire which I think would be fine. Would that be overstuffed? To run the 6-50 outlet I'd want to run 6AWG to it though right since it's a 50A breaker?

Maybe I misunderstood your situation.

I thought you were describing a situation where you needed to route individual circuits from a panel that is remote from the garage. In that case, it will be easier in the long run to install a sub panel in the garage and make garage additions from there.

If your panel is already in the garage then you are good with the existing panel. That panel isn't even close to full assuming that it allows double density breakers.

There is a 100A sub panel in garage and that is what I linked in above. It has 3 openings available. I think i'm going to use 2 for a 50A 220 breaker w/ a 6awg run/6-50 plug directly below the box and use an extension cord for warning around the garage.

A 5 hp comp requires 10 in pipe, that will go 1/2 easy. Your welder will work 10 in pipe. 40A for the comp and breakers from 30 to 50 or the welder. I have a convenience outlet on panels around the shop, various wire on them as it was free at the time but at the welder home I have 1 with a 6 wire 50 for the heavy mig, 2 of then 10-50 for plasma and a DC stick and 2 of them 10-30 for compact migs.
I have a welder outlet on the hoist wire, a 10-30 so I can plug mig there.
I have installed a couple few for buds using old work boxes below the panel. The welder could use a 10 cable, depending on model the comp may need an 8 in cable to meet the code.

I think I am a bit confused here w/ the 10AWG for a 5 HP compressor motor. The manuf. docs state I need a 40A but if I run THHN 90C 10AWG the ampacity chart says the limit is 30A which clearly will not work.


Thanks for all the input guys, I am trying to do this one and do it right.

Dave

 

[pattenp]

You don't use 90C to determine ampacity of THHN under normal conditions, use 75C. 90C is only used when doing derating calculations. #10 THHN at 75C is 35A. By the NEC, 5HP is 28A, so 28A X 125% = 35A.

 

[TT_Vert]

Ahh just found the NEC info. I looked here and it shows something different. Are you saying I should go w/ the NEC info vs. the compressor manufacturers requirement which is 40A? Just curious as I don't know what info to follow and why at this point. Perhaps I didn't link the manual info for the compressor here, they say it requires a 40A breaker. If I go w/ the compressor docs I have to run a 40A breaker which would require 8AWG right since 10AWG limit is 35A?

Dave

 

[pattenp]

Can you tell me where you get this data so I can look? I looked here and it shows something different.

That chart is using the most conservative numbers in the code based on small conductor amp limits. There are exceptions for motor circuits. You need to understand all the ins and outs of the NEC to know what wire sizes can be used where and when. My number are coming directly from the NEC charts. Do a search for NEC Table 310.15(B)(16) and for motors Table 430.248

 

[TT_Vert]

That chart is using the most conservative numbers in the code based on small conductor amp limits. There are exceptions for motor circuits. You need to understand all the ins and outs of the NEC to know what wire sizes can be used where and when. My number are coming directly from the NEC charts. Do a search for NEC Table 310.15(B)(16) and for motors Table 430.248

Thanks I'll read that right now. I edited my text as you were replying, could you address the following??

Are you saying I should go w/ the NEC info vs. the compressor manufacturers requirement which is 40A? Just curious as I don't know what info to follow and why at this point. Perhaps I didn't link the manual info for the compressor here, they say it requires a 40A breaker. If I go w/ the compressor docs I have to run a 40A breaker which would require 8AWG right since 10AWG limit is 35A?

 

[pattenp]

Motor circuits can be on breakers larger than the actual ampacity of the wire. If the compressor is hardwired you can use a 40A breaker on #10. The motor on the compressor should have it's own overload protection and the breaker only serves as short circuit protection. NEC 430.52

Edit: This only applies to hardwired motor circuits , no outlets and plugs.

 

[TT_Vert]

Motor circuits can be on breakers larger than the actual ampacity of the wire. If the compressor is hardwired you can use a 40A breaker on #10. The motor on the compressor should have it's own overload protection and the breaker only serves as short circuit protection.

Great thank you. It is not hardwired but I can mark the outlet so it is for the compressor use only. And it's actually behind a rack so it's not easily accessible anyway. So I will run 10AWG to a 40A breaker and be done with it. Does anyone see any issue w/ that? If so, i'll just hardwire it to alleviate any issues.

 

[pattenp]

Great thank you. It is not hardwired but I can mark the outlet so it is for the compressor use only. And it's actually behind a rack so it's not easily accessible anyway. So I will run 10AWG to a 40A breaker and be done with it. Does anyone see any issue w/ that?

Nope. Can't do that. If a plug then the plug and outlet are to be HP rated and the breaker and wire are to match the outlet amp rating. NEC 430.42(C)

 

[pattenp]

Normal NEMA outlets such as a 6-50 is rated to 3HP, this is why compressors that are 5HP should be hardwired.

 

[TT_Vert]

Fair enough thank you for all the information, i will hardwire. Can you perhaps tell me why the same plug that can sustain 50A loads cannot sustain the current draw from a 3.1HP motor?

Dave

 

[pattenp]

The issue with using a plug that's not HP rated for the motor being used is not about the running amps of the motor and what the amps the plug can handle but about the plug and outlet being considered a disconnect. If you pull the plug in an emergency situation such as a locked rotor the sparks can fly and be a physical safety risk. Higher HP motors using plugs need to use Pin and Sleeve plugs which provide cover protection of the Pins so any arcing is contained when disconnecting.

 

[wyliesdiesels]

The other possibility is unplugging it while its starting. Motors have inherrent in-rush currents while starting and In-rush current is 4x-8x FLA so for a 5HP motor that can be over 100a.

This creates arc flash potential...

 

[TT_Vert]

Ok so I am going to hard wire. Anyone care to offer suggestions there? There is a single gang box there now. I went to home depot to look at what they had today. I saw one option w/ what I think they call a blade switch but it was something like $60 for one w/ high enough amperage. I also saw a 2 position load center but that requires a redundant 40A breaker. What are you guys doing? For aesthetics it'd be nice to mount the box over the existing box and feed the 10 into the back of the box and then feed the cable from the compressor into this. From there can I just run a 10-2 romex whip from the compressor to the load center or equivalent?

 

[Norcal]

Ok so I am going to hard wire. Anyone care to offer suggestions there? There is a single gang box there now. I went to home depot to look at what they had today. I saw one option w/ what I think they call a blade switch but it was something like $60 for one w/ high enough amperage. I also saw a 2 position load center but that requires a redundant 40A breaker. What are you guys doing? For aesthetics it'd be nice to mount the box over the existing box and feed the 10 into the back of the box and then feed the cable from the compressor into this. From there can I just run a 10-2 romex whip from the compressor to the load center or equivalent?

Get a 60A fusible A/C pullout disconnect, cheap & effective.

 

[sreeb]

Get a 60A fusible A/C pullout disconnect, cheap & effective.

I'm using a non-fusible A/C pullout disconnect.

https://www.homedepot.com/p/Square-...kW-Non-Fuse-AC-Disconnect-QO200TRCP/202353314

I'm not sure if there is a code requirement for any disconnect. From an electrical point of view, you could probably just use a handy box and some wire nuts.

I like being able to pull the disconnect and put it my pocket when working on the compressor.

 

[brewchief]

Ok so I am going to hard wire. Anyone care to offer suggestions there? There is a single gang box there now. I went to home depot to look at what they had today. I saw one option w/ what I think they call a blade switch but it was something like $60 for one w/ high enough amperage. I also saw a 2 position load center but that requires a redundant 40A breaker. What are you guys doing? For aesthetics it'd be nice to mount the box over the existing box and feed the 10 into the back of the box and then feed the cable from the compressor into this. From there can I just run a 10-2 romex whip from the compressor to the load center or equivalent?

You can't use 10-2 romex to make a whip, it's only rated at 30 amps, an A/C whip will get you #10 thwn wires, liquid tite conduit and fittings for less then you can buy them separate. You don't need a means of disconnect if the compressor is in sight and within 50 feet, you can use one if you'd like and most will agree that it's a good idea to use one.

If you find some things in the NEC confusing you're not alone, heck I've seen two masters arguing over some parts of it.

 

[TT_Vert]

Yeah I actually had that AC disconnect box in my hand at HD. So is it acceptable to mount the ac disconnect atop the single gang box and run the wire through a knockout to the AC disconnect terminals? I will locate AC liquid tite conduit. Don't most of these compressors come w/ an unwired plug w/ something like 10 wire to begin with? Also, can your answer why NEC 403.248 for 5HP states 28A @230V yet a 10 Romex whip (which is rated to 30A) is not acceptable? Is extra overhead to be given when calculating? Is this also written in the NEC code somewhere?

Thanks much, learning a ton lately.

Dave

 

[wyliesdiesels]

Romex aka NM-b is building wire. Its not permitted to be used as appliance and equipment cords...

For motor circuits, they are sized like a continuous load so need to apply 1.25% to the FLC, which would be 35a.

#10 NM-b is limited to 30a. See 240.4D

 

[TT_Vert]

Ahh so romex is not THHN, that makes sense. And mounting this ac disconnect atop the open single gang box and running wires though the knockout in back is acceptable?

Thanks again.
Dave