240v in detached shop

[RedTravis88]

I'm looking to verify what I need for a Lincoln WeldPak 180i welder, as well as an 80 gal 15a compressor (never at the same time) in my existing detached workshop.

I have 60a service feeding the sub panel in my workshop, which currently has (6) 20a single pole breakers feeding the lights and receptacles, and (1) double pole 20a breaker feeding two 240 receptacles.

I already have some concerns because the previous owner used 10/2 Romex to the first 20a/240v receptacle, then ran 12/2 to another 20a/240v receptacle.

My welder has a NEMA 6-50 plug, but the manual states a 20a breaker is sufficient. My compressor currently doesn't have a plug attached. So am I safe to wire a 6-50 receptacle to the existing 20a circuit? And just use a 6-50 plug for both units?

If not, do I need to (can I?) replace the breaker with a 40a double pole and run 8/2 Romex to my receptacle?

 

[rocksnstumps]

For reference my Millermatic 210 welder also has a 6-50P plug but from the factory the cord itself is 12/3 STOW. Manual for my unit states 30 amp max recommended breaker. Think pretty common on welders due to duty cycle to have that style plug but not use an up sized wire or breaker. I would not go with the larger 40 amp breaker if using for the welder only. Put a Welder Only label on that receptacle if it makes you feel better for the next guy.

Edit: curious what size wire goes from your plug to the 180i welder. Bet it is 12 AWG or under also

 

[u2slow]

I use 20A circuits for my welders too. I made a 8-10' adapter/extension cord to go from 6-50r to 6-20p.

 

[wyliesdiesels]

If not, do I need to (can I?) replace the breaker with a 40a double pole and run 10/2 Romex to my receptacle?

only if youre using it for the welder. otherwise 10/2 NM is limited to 30a

 

[RedTravis88]

For reference my Millermatic 210 welder also has a 6-50P plug but from the factory the cord itself is 12/3 STOW. Manual for my unit states 30 amp max recommended breaker. Think pretty common on welders due to duty cycle to have that style plug but not use an up sized wire or breaker. I would not go with the larger 40 amp breaker if using for the welder only. Put a Welder Only label on that receptacle if it makes you feel better for the next guy.

Edit: curious what size wire goes from your plug to the 180i welder. Bet it is 12 AWG or under also

Looked at the welder's wire size today, and it's actually 14/3. But that doesn't make sense to me since 14ga is only rated to 15a... What am I missing?

I use 20A circuits for my welders too. I made a 8-10' adapter/extension cord to go from 6-50r to 6-20p.

Interesting. Looking more closely at the welder today, and using voltages for anything above 12ga steel it recommends connecting to a 25a circuit. Not sure why the manual says 20a is sufficient is that's the case.

only if youre using it for the welder. otherwise 10/2 NM is limited to 30a

My bad, I meant to say 8/2 NM. I'll edit that.

 

[wyliesdiesels]

Looked at the welder's wire size today, and it's actually 14/3. But that doesn't make sense to me since 14ga is only rated to 15a... What am I missing?

Majority of small and medium size welders have limited duty cycle allowing for smaller wire gauges. The wire wont have enough time to heat up

 

[theoldwizard1]

I already have some concerns because the previous owner used 10/2 Romex to the first 20a/240v receptacle, then ran 12/2 to another 20a/240v receptacle.

My welder has a NEMA 6-50 plug, ...

A NEMA 6-50 receptacle should use 10/3 or 12/3 NM-B (L1, L2, neutral and ground). If it is in metal conduit (EMT) that is connected to ground at the load center then the conduit is your ground. (Can you LEGALLY use the uninsulated wire inside the NM-B as neutral when installed in EMT ?)

 

[Snapped-off]

A NEMA 6-50 receptacle should use 10/3 or 12/3 NM-B (L1, L2, neutral and ground). If it is in metal conduit (EMT) that is connected to ground at the load center then the conduit is your ground. (Can you LEGALLY use the uninsulated wire inside the NM-B as neutral when installed in EMT ?)

Yes, I know, neither your welder or compressor use neutral. IMHO, cut the plug off the welder and install a NEMA 6-20 plug on it and on the compressor. Replace both outlets with NEMA 6-20 receptacles.

Where does the neutral go on a 6-50?

 

[sparky 1971]

A NEMA 6-50 receptacle should use 10/3 or 12/3 NM-B (L1, L2, neutral and ground).

what kind of jibberish is that? What's the purpose of the neutral?

If it is in metal conduit (EMT) that is connected to ground at the load center then the conduit is your ground.

then what's the point of using romex?

(Can you LEGALLY use the uninsulated wire inside the NM-B as neutral when installed in EMT ?)

No

Yes, I know, neither your welder or compressor use neutral. IMHO, cut the plug off the welder and install a NEMA 6-20 plug on it and on the compressor. Replace both outlets with NEMA 6-20 receptacles.

Why?

 

[BrandonV]

Looked at the welder's wire size today, and it's actually 14/3. But that doesn't make sense to me since 14ga is only rated to 15a... What am I missing?

The welder is considered listed equipment. Like the comment above, it's more than capable to handle the demands of welding due to the duty cycle and the fact that 14 gauge can handle more amps than you can think in reality.

 

[PCustoms]

A NEMA 6-50 receptacle should use 10/3 or 12/3 NM-B (L1, L2, neutral and ground). If it is in metal conduit (EMT) that is connected to ground at the load center then the conduit is your ground. (Can you LEGALLY use the uninsulated wire inside the NM-B as neutral when installed in EMT ?)

Yes, I know, neither your welder or compressor use neutral. IMHO, cut the plug off the welder and install a NEMA 6-20 plug on it and on the compressor. Replace both outlets with NEMA 6-20 receptacles.

Do you enjoy making things up on a consistent basis?

 

[mm08822]

OP, post a picture of compressor motor nameplate. Necessary info for determining what can be done for both pieces of equipment.

 

[mm08822]

Do you enjoy making things up on a consistent basis?

41K posts ..............

 

[wyliesdiesels]

Do you enjoy making things up on a consistent basis?

gotta be it. he does this all the time. then never corrects the misinformation when called out

 

[wyliesdiesels]

A NEMA 6-50 receptacle should use 10/3 or 12/3 NM-B (L1, L2, neutral and ground). If it is in metal conduit (EMT) that is connected to ground at the load center then the conduit is your ground. (Can you LEGALLY use the uninsulated wire inside the NM-B as neutral when installed in EMT ?)

what the what?

a 6-50 does not have a neutral.

pointless to run NM-b in EMT.

no you cannot use the bare EGC in NM-b as the neutral for any install.

Yes, I know, neither your welder or compressor use neutral. IMHO, cut the plug off the welder and install a NEMA 6-20 plug on it and on the compressor. Replace both outlets with NEMA 6-20 receptacles.

thats horrible advice. the 6-50 on the welder is perfectly fine and a 6-20 on the compressor is most likely undersized due to HP rating on motor.

please just stop with this non-sense

 

[RedTravis88]

OP, post a picture of compressor motor nameplate. Necessary info for determining what can be done for both pieces of equipment.

Here you go.



I ended up running 12/2 to a 6-20 receptacle just for the compressor.

I'll likely run a second circuit on a 40a breaker for the welder.

But also, look what I found when I started looking a little more closely at the existing wiring...



Needless to say I won't be using it for anything.

what the what?

a 6-50 does not have a neutral.

pointless to run NM-b in EMT.

no you cannot use the bare EGC in NM-b as the neutral for any install.


thats horrible advice. the 6-50 on the welder is perfectly fine and a 6-20 on the compressor is most likely undersized due to HP rating on motor.

please just stop with this non-sense

I'm no electrician, but I'm glad I'm not the only one who thought he was smoking something.

 

[Chuckster in NJ]

what the what?


thats horrible advice. the 6-50 on the welder is perfectly fine and a 6-20 on the compressor is most likely undersized due to HP rating on motor.

please just stop with this non-sense

I learn something everyday on this forum.…….. I find it amazing there aren’t more electrocutions or electrical fires.

 

[u2slow]

I ended up running 12/2 to a 6-20 receptacle just for the compressor.

Identical specs on my compressor ... and it came with a factory 6-20p cord plug.

 

[mm08822]

I learn something everyday on this forum.…….. I find it amazing there aren’t more electrocutions or electrical fires.

Dead men don't tell tales and those who really FUBAR'd don't talk about it

 

[dave*99]

Where does the neutral go on a 6-50?

That's it, you did it now. Flagged the usual nonsense. Now he won't be back to this thread.

 

[wyliesdiesels]

Here you go.



I ended up running 12/2 to a 6-20 receptacle just for the compressor.

thas a 3hp motor

technically need 21a rated wire (17a x 1.25a) to be code compliant but the 12 NM-b should be fine. The 6-20p (and R) are most likely not rated for 3hp so keep that in mind when going to disconnect it while running should you have to.

I'll likely run a second circuit on a 40a breaker for the welder.

Just run a 50a circuit.

But also, look what I found when I started looking a little more closely at the existing wiring...



Needless to say I won't be using it for anything.

yikes. wonder if it does indeed have asbestos. Thats the first time ive ever seen that brand.

I'm no electrician, but I'm glad I'm not the only one who thought he was smoking something.

he does it regularly....

 

[Cruzan80]

thas a 3hp motor

technically need 21a rated wire (17a x 1.25a) to be code compliant but the 12 NM-b should be fine. The 6-20p (and R) are most likely not rated for 3hp so keep that in mind when going to disconnect it while running should you have to.

Asking to better educate myself...
Any"quotes" from you were in italics so as not to break up the line reading.

The SPL means you go off the Amps, vs the FLA tables, correct? So the 3HP you mention in your first sentence is a best estimate, and not to be used for FLA tables?

Where did you get 21A rated wire (17a x 1.25a) from? The picture I see has 15A listed, not 17, and a SF of 1.0. Does the x1.25a not relate to the service factor, but is a standard multiplier?

 

[wyliesdiesels]

Asking to better educate myself...
Any"quotes" from you were in italics so as not to break up the line reading.

The SPL means you go off the Amps, vs the FLA tables, correct? So the 3HP you mention in your first sentence is a best estimate, and not to be used for FLA tables?

Where did you get 21A rated wire (17a x 1.25a) from? The picture I see has 15A listed, not 17, and a SF of 1.0. Does the x1.25a not relate to the service factor, but is a standard multiplier?

When the HP isnt listed you are to use the FLA and correspond that with the FLC tables in 430.248

15a is most likely a 3HP motor because of the values we see in the above table. so then you take the FLC amps for a 3hp motor (17) and multiply that by 1.25.

Code does not use the SF for sizing wire. the SF only comes into play when setting overloads on motor starters.

 

[Cruzan80]

Gotcha. I had thought (sounds like mistakenly), that SPL meant you could use the nameplate amps directly, rather than cross-reference to the nearest approximate HP and then use that HP amps (from the chart).

I had thought the 1.25 was a standard multiplier, but could not remember when SF came into play.

If the motor had come with a 6-20 style plug from the manufacturer (and relevant certification), it meant that they had done the necessary testing to ensure the plug/amperage was adequate for the specific setup that was sold, regardless of motor nameplate value (possibly) indicating otherwise? I understand it did not in this case, just a hypothetical.

 

[u2slow]

thas a 3hp motor

technically need 21a rated wire (17a x 1.25a) to be code compliant but the 12 NM-b should be fine. The 6-20p (and R) are most likely not rated for 3hp so keep that in mind when going to disconnect it while running should you have to.

Technically, an SPL rated motor on a compressor comes with a factory cord plug. I already stated what mine came with.

Thinking it needs 21A sized conductors is incorrect. The nameplate says 15A.

 

[sparky 1971]

Technically, an SPL rated motor on a compressor comes with a factory cord plug. I already stated what mine came with.

Thinking it needs 21A sized conductors is incorrect. The nameplate says 15A.

Lucky you. Mine didn't come with a cord but cords were hanging next to the compressors for additional $. I decided I'd make my own cord when I got it home. Then I discovered I didn't have a 6-20P or R. Or 12/3 cord. So I hooked it up temporarily using a two pole switch and some 14/3 SJ cord. That was four years ago and nothing has changed.

 

[wyliesdiesels]

Gotcha. I had thought (sounds like mistakenly), that SPL meant you could use the nameplate amps directly, rather than cross-reference to the nearest approximate HP and then use that HP amps (from the chart).

SPL is not something even mentioned in the NEC

I had thought the 1.25 was a standard multiplier, but could not remember when SF came into play.

If the motor had come with a 6-20 style plug from the manufacturer (and relevant certification), it meant that they had done the necessary testing to ensure the plug/amperage was adequate for the specific setup that was sold, regardless of motor nameplate value (possibly) indicating otherwise? I understand it did not in this case, just a hypothetical.

the 6-20p that comes on a compressor from the factory is listed for use in that specific setup as tested by the NRTL. doesnt mean that a store bought 6-20p or 6-20r will have the same HP rating.

 

[wyliesdiesels]

Technically, an SPL rated motor on a compressor comes with a factory cord plug. I already stated what mine came with.

not true for every SPL rated motor. not even close.

Thinking it needs 21A sized conductors is incorrect. The nameplate says 15A.

show me where the NEC says to size the circuit conductors based on the nameplate FLA. go ahead I'll wait.

 

[Cruzan80]

the 6-20p that comes on a compressor from the factory is listed for use in that specific setup as tested by the NRTL. doesnt mean that a store bought 6-20p or 6-20r will have the same HP rating.

Understood. Just was trying to confirm that if something ships with an attached cord, even if it would seem to violate what I can do with off the shelf, they have tested and found compliant...for that exact set of components.

 

[u2slow]

show me where the NEC says to size the circuit conductors based on the nameplate FLA. go ahead I'll wait.

A consumer product featuring a factory cord plug needs nothing more than an appropriate circuit with a matching receptacle.

 

[RedTravis88]

Just run a 50a circuit.

yikes. wonder if it does indeed have asbestos. Thats the first time ive ever seen that brand.

The issue with that is that my sub panel is only in a 60a breaker from the main panel. I'm thinking I'm pushing it with the current 20a, the other (4) 20a for the lights/receptacles, and the 40a in planning to use for the welder. Granted, I wouldn't be using the welder and compressor at the same time, but I assume there would be an issue with putting a 50a in there.

Also, from what I read about the Techbestos wire, it sounds like the fabric lining does indeed have asbestos in it.

When the HP isnt listed you are to use the FLA and correspond that with the FLC tables in 420.248

15a is most likely a 3HP motor because of the values we see in the above table. so then you take the FLC amps for a 3hp motor (17) and multiply that by 1.25.

Code does not use the SF for sizing wire. the SF only comes into play when setting overloads on motor starters.

Interesting stuff. Way over my head.

 

[wyliesdiesels]

A consumer product featuring a factory cord plug needs nothing more than an appropriate circuit with a matching receptacle.

you still havent cited any code to backup your claim. i said nothing about the factory plug. my previous comment stated how to size the wire. please try again and this time post applicable codes

 

[wyliesdiesels]

The issue with that is that my sub panel is only in a 60a breaker from the main panel. I'm thinking I'm pushing it with the current 20a, the other (4) 20a for the lights/receptacles, and the 40a in planning to use for the welder. Granted, I wouldn't be using the welder and compressor at the same time, but I assume there would be an issue with putting a 50a in there.

merely installing a 50a breaker doesnt mean you will actually use 50a. but with that logic, even a 40a breaker could cause the 60a trip with 20a of load from the other circuits.

in reality, without the welder or compressor, I doubt youre using even 10a with the lights and receptacles.

keep in mind, some welders can pull 50a intermittently. so if you put it on a 40a, you could trip it. all depends on the welder, settings, and duty cycle