Welder / Wiring for Small Garage

   / Welder / Wiring for Small Garage #61  
aircommuter said:
Most 120/240 machines include an adapter. Some machines cone with a 4 wire plug and I have one that is 3 phase also.
Click to expand...
I hear you but consider also that machine like the Hobart Handler 210MVP has plug options that are not exactly a "adapter"....
 

Attachments

  • Screenshot 2023-06-28 194917.jpg
    Screenshot 2023-06-28 194917.jpg
    142.8 KB · Views: 59
   / Welder / Wiring for Small Garage #63  
MAX-24-Dean said:
True, except the code has to give allowance for Physics/Theory. One example would be motor loads. Breakers for motor loads need to be sized to allow for the inrush of current. So the NEC allows for breakers to be sized at approximatley 250% of motor running amps. As long as the conductor size has sufficient ampacity to serve the running amps load plus 125%, the breaker can be larger than the running amp by up to 2.5 times. (My paraphrase, Not code verbage cause I'm not taking the time to look it up.)

If you look at Art 630 of the NEC for overcurrent protection of welder conductors, the verbage is basically that conductors supplying welders shall be protected by an overcurrent device rated no more than 200% of the conductor ampacity.
So a 20 amp rated conductor could have a 40 amp breaker protecting it.
There is a formula for calculating this in 630.12.B



For inverter resistance welders. You would use Art 630.31.A, basically states that the conductor ampacity shall not be less than 70% of the rated primary current for seam welders and automatically fed welders that can be adjusted for different values of primary current and duty cycle. And not less than 50% of the rated primary current if there are other circumstances.
There are to many variables to go into here.

At least for the last 25 years of doing electrical drawings the minimum conductor sizes for welders was given in the operators manual for each welder. See attached sheets that have been previously posted showing this. I have never placed an approved stamp on a one line drawing without looking at the engineered data in a welders operators manual. The engineering calculations are placed in the operators manual, so I never bother with figuring it out. It has become thier liabilty.

I did at times have to have pictures of nameplate data sent, so I could size conductors and overcurrent protective devices.

From the welders manuals in this thread. One manual stated the minimum counductor size being a #14, the other manual stated the minimum conductor size as being #12. Both manuals stated that a "hard service cord" of #12 conductors were the minimum for an extension cord for up to 50 feet in length. The manuals also had the sizes for overcurrent protection provided.
Click to expand...
Seems like that latitude would be for a hard wired welder, otherwise something else could be plugged in there.
 
   / Welder / Wiring for Small Garage #65  
WranglerX said:
Directly from Hobart Handler 210MVP Manual...



View attachment 808353
Click to expand...
so the point you are making is that the min circuit conductor size is less than what i stated?
Granted on this specific unit that is true, I would still run #10 and a 30 amp breaker you could go down on the conductor size but this is an extension to an existing service that has some VD to it already, and not being too sure of the exact configuration i would error on the side of less VD in this case.
the cost delta between #14 (marginal) and #10 for this circuit is far outweighed by the PITA of dealing with issues arising on saving $30 up front and then having to redo it.

as a side note when i'm giving electrical advise on the internet i try to avoid the bare min advice if i'm not sure of the audience and the exact install details.
 
Last edited:
   / Welder / Wiring for Small Garage #66  
aircommuter said:
Seems like that latitude would be for a hard wired welder, otherwise something else could be plugged in there.
Click to expand...
max is correct the min conductor size is less than the amps of the cb required to run the machine due to duty cycle of the unit. it is a welder receptacle and if something else is plugged in the owner needs to re-evaluate the install.
I would still not do it this way unless i was very certain of the exact details of the existing service, notice the 53 foot max length of the circuit. also if you look at the duty cycle for this welded it is low 60% @ 150a on a 210 amp welder other welders with the same 210A capacity and a better duty cycle would require a larger conductor.
 
   / Welder / Wiring for Small Garage #67  
DaBear3428 said:
so the point you are making is that the min circuit conductor size is less than what i stated?
Granted on this specific unit that is true, I would still run #10 and a 30 amp breaker you could go down on the conductor size but this is an extension to an existing service that has some VD to it already, and not being too sure of the exact configuration i would error on the side of less VD in this case.
the cost delta between #14 (marginal) and #10 for this circuit is far outweighed by the PITA of dealing with issues arising on saving $30 up front and then having to redo it.

as a side note when i'm giving electrical advise on the internet i try to avoid the bare min advice if i'm not sure of the audience and the exact install details.
Click to expand...
The point is the spec. the manufacturer recommends in right there in the manual for the unit....

Also note the OP stated two different welders, and the manual for each welder has a different set of values...

 
   / Welder / Wiring for Small Garage #69  
WranglerX said:
The point is the spec. the manufacturer recommends in right there in the manual for the unit....

Also note the OP stated two different welders, and the manual for each welder has a different set of values...

Click to expand...
and my point is that that spec is met and exceeded by my advice and i have already given my reasoning behind my advice, can he possibly get by with less yes but there are limitations on that spec page did you get that?

also note my advice factors in an allowance for higher duty cycle equipment.
 
   / Welder / Wiring for Small Garage #70  
You must log in or register to reply here.
 

Footer Links 1

Top