Fusible Switch Circuit

ezridermnFebruary 2, 2011

Hi.

I want to wire an electrical circuit in my home to run a small Miller TIG welder. The welder rating is 230v at 20amps. The max standard circuit breaker/fuse is designated at 30amps. Their recommendation is to use a 30amp fusible switch between the source and the machine. They also designate a minimum 14 gauge conductor size. (which sounds lite to me)

Specifics to my home. The main panel (200 amp service) is located about 75' from the location of the 230v outlet to run the welder.

My primary question relates to configuring the circuit to use a fusible switch per their suggestion. Do I put a 30amp breaker in the main panel, then run wire to a 30 amp fusible switch located near the welder and then make the connection to the outlet from there.

If that isn't the correct configuration I would appreciate it if you could tell me what is the right way to do it.

Also, I would like to know what gauge wire I should use to carry the 20 amp load over 75' to the welder.

Thanks in advance for your help!

Bob

Thank you for reporting this comment. Undo
bus_driver

The 30 amp breaker is the "fusible switch", no additional required. Article 630 in the NEC permits electric welders to be on circuits with apparently undersized wire (tables in the Article show the sizes) in cases where the duty cycle is below 100%. Your welder might be only 20%. Some of the imports are only 6%. 20% means what one can weld 2 minutes out of very 10 and the welder is permitted to cool for the other 8 minutes. The conductors also cool during that time. I would use #12 for the application. #10 would be better but not necessary.

    Bookmark   February 2, 2011 at 11:18AM
Thank you for reporting this comment. Undo
brickeyee

"Article 630 in the NEC permits electric welders to be on circuits with apparently undersized wire"

Welding equipment, induction motors, and hermetic compressors are have there own code sections.

The wires are not undersized, but based on the characteristics of the equipment.

This equipment contains built in thermal overload protection, so all the breaker is doing is protecting the feeder against short circuits.

The low duty cycle of many welders allows plenty of time for the wires to cool off.

General purpose circuits (15 and 20 amp, 120 V) feeding multiple loads and used many times in every installation are designed with extra margin (#14 wire at 15 amps, #12 at 20 amps) to ensure safety.

    Bookmark   February 2, 2011 at 5:18PM
Thank you for reporting this comment. Undo
ezridermn

Hey Guys. Sounds like I now know what I need to know. Thanks for the help!

    Bookmark   February 3, 2011 at 9:53AM
Sign Up to comment
More Discussions
Does a refrigerator need to be on a separate circuit?
Does a refrigerator need to be on a separate circuit?...
rontero
Crawl Space Junction Boxes: inspection and capping
Hello. I'm in the process of crawl space improvement....
SparklingWater
How to get garage freezer to work in cold weather
I have a 7-year-old GE refrigerator/freezer in my unheated,...
amyf5
Help with 240V 50A location
I'm trying to do a challenging kitchen layout. I will...
12crumbles
Insulation in electrical box
While in my attic the other day I saw an open electrical...
sgilliatt
People viewed this after searching for:
© 2015 Houzz Inc. Houzz® The new way to design your home™