I've run across this twice, now. In a large plant, they want 10 receptacles for 50A (100A breaker) welders scattered about, but they merely own 2 or 3 welders. When sizing the feeders, do you have to pretend that all 10 are connected at once? I see no diversity in the Code for welders. Am I missing something?
Diversity for welder receptacles?
- Thread starter donw
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I would size each feeder for the 50A load of the welder.
I would size each distribution panel or bus for the load of the welders that they own. For instance if (5) outlets are fed from Bus A and (5) from Bus B, each Bus gets the (2) welder load for feeder sizing.
Now, what happens if they buy more welders in the future? Who can see the future?
I would size each distribution panel or bus for the load of the welders that they own. For instance if (5) outlets are fed from Bus A and (5) from Bus B, each Bus gets the (2) welder load for feeder sizing.
Now, what happens if they buy more welders in the future? Who can see the future?
- Location
- Windsor, CO NEC: 2017
- Occupation
- Service Manager
Who needs to?Jim H said:
How can you apply 630.11(B) to non-existent welders we suspect may exist in the future?
In the past, welders have been offered as evidence that an individual branch circuit could supply many receptacles, due to the one welder moving around the shop. If multiple welders had different characteristics, then different receptacle/plug configurations could be chosen to keep three welders from overloading a circuit designed for one at a time.
If all three welders had the same plug, then the circuit should be designed to carry all three, IMO.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
This is really not so different from a typical multi-receptacle branch circuit. We don't have to design for full loading of every receptacle simultaneously.
- Location
- Massachusetts
donw said:
Not in dwelling units and it makes little difference in non-dwelling units, the moment you install one 20 amp duplex on a 20 amp circuit it can easily be overloaded regardless of the 180 VA requirement.
I agree with Larry, you do not have to call them welder outlets and you do not have to take advantage of the leniencies that 630 allows.
You could put 10 outlets on a 50 amp breaker and call it a day, it is a design issue.
What does the customer want today, what do they expect in the future and what can they afford are the issues at hand.
Cheapest route; If they simply use the welders once in a while the GP outlet route will work fine. One breaker ten outlets.
More money; If they are a welding shop and expect to run 10 welders simultaneously then you would want to use 630 but to do so you must know the specifics of the welders.
Article 630 lets you take some real liberties with wire sizing depending on the duty cycle of the welders.
Most expensive; Ten 50 amp outlets with a service that can supply them all at full current simultaneously on top of the other building loads. (serious over kill but bullet proof)
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