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Old 11-19-2010, 01:29 PM   #1
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Default Welder Receptacle

I've got a Hobart welder that requires #8 conductors and a max of 70 amp over current protection. I'm scratching my head on how I can put in a code compliant receptacle while keeping costs down.

Options:

1. 50 amp receptacle, #8, with 70 amp breaker
2. 70 amp receptacle, #4, with 70 amp breaker

I think option 2. is the only way to be code compliant. Am I missing something?

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Old 11-19-2010, 01:35 PM   #2
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Quote:
Originally Posted by nitro71 View Post
I've got a Hobart welder that requires #8 conductors and a max of 70 amp over current protection. I'm scratching my head on how I can put in a code compliant receptacle while keeping costs down.

Options:

1. 50 amp receptacle, #8, with 70 amp breaker
2. 70 amp receptacle, #4, with 70 amp breaker

I think option 2. is the only way to be code compliant. Am I missing something?
Yeah, you will be stuck with a 100 amp receptacle, I doubt you will find a 70.

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Old 11-19-2010, 04:13 PM   #3
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I would recommend reading Article 630.

Chris
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Old 11-19-2010, 04:15 PM   #4
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I would recommend reading Article 630
Always good advice but I do not think 630 changes the rules for receptacle ratings vs OCP rating.
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Old 11-19-2010, 05:29 PM   #5
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Always good advice but I do not think 630 changes the rules for receptacle ratings vs OCP rating.
But the rules in 630 do change the way that the determine the ampacity of the branch circuit conductors and the overcurrent protective device.

We need to know the Ieff value from the nameplate of the welder or calculate the load using the rated primary current multiplied by the multiplier listed in Table 630.11(A) for the duty cycle.

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Old 11-19-2010, 05:56 PM   #6
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Manufacturer figured that out in their recomendations. Pretty sure that BBQ is correct about the receptacle ratings. That was my feeling also.
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Old 11-22-2010, 03:12 PM   #7
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Just a side note. Price jumps tremendously above 50 amps for receptacles and plugs. Did some pricing and it's expensive. If I had a weld shop customer on a budget I'd recommend hardwiring and disconnects.
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Old 11-22-2010, 04:06 PM   #8
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Just a side note. Price jumps tremendously above 50 amps for receptacles and plugs. Did some pricing and it's expensive. If I had a weld shop customer on a budget I'd recommend hardwiring and disconnects.
Yup. Most often, that puts you in pin and sleeve receptacle territory. Mucho dinero.
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Old 11-22-2010, 04:55 PM   #9
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What model is he Hobart welder? How are you protecting person if they unplug/plug the welder out/in? Have you contacted the Hobart and ask for recommendations? Need more detailed specs on unit.
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Old 11-22-2010, 05:04 PM   #10
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What model is he Hobart welder? How are you protecting person if they unplug/plug the welder out/in? Have you contacted the Hobart and ask for recommendations? Need more detailed specs on unit.
I like these interlocked disconnect/receptacles. The one in my picture is a Mennekes, but Hubbell and Leviton and a few other people make similar ones. The switch can't be turned on until the plug is in, and the plug can't be removed until the switch is turned off.



Contacting the manufacturer for receptacle recommendations is absurd, however. We're electricians. Do your job. Leaning on the manufacturer to spec construction materials is pretty rookie, in my opinion.
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Old 11-22-2010, 11:35 PM   #11
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What model is he Hobart welder? How are you protecting person if they unplug/plug the welder out/in? Have you contacted the Hobart and ask for recommendations? Need more detailed specs on unit.
Just like any other appliance that is running. If you unplug it while it's operating it's going to arc. Recs are above in the thread. That is a slick looking disco MD.

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