Interchangeable 208/220/230V "Receptacle"

[FrancisJ]

I'm continuing the build out of the (basically all concrete) "Hurricane Proof" 24 x 72 garage/shop and the next challenge is building a "Receptacle Panel" (using a SINGLE female NEMA receptacle) to accommodate:

(a) 7.5hp 208/230V Single Phase 80 Gallon Air Compressor (26.0 SCFM @ 175psi) (Calculations: Max Input Amperage 45A @ 220V)

(b) MillerMatic 211 MIG Welder (Max Input Amperage 16.6A @ 230V)

(c) Miller CST 280 Stick Welder (Max input Amperage 43.9A @ 220V)

(d) Lincoln Square Wave TIG Welder (Max Input Amperage (Max Input Amperage 22A @ 220V)

The idea is to only plug in one device at a time (obviously). The circuit is a separate subpanel (downstream of a 60A main panel breaker), on a 50AMP GE GFCI Breaker, two new copper ground rods, separate ground and neutrals (per NEC) and I'm running 6-3 UF wire (over-spec'd at 55A) from the 50A GFCI over to the Receptacle Panel (approx 12 foot run) with the following female connector:

http://www.graybar.com/store/en/gb/3-pole-4-wire-50a-125-250v-grounding-receptacle-14-50r-88127949?cm_mmc=pla:google-_-googleshopping-_-gb5420-_-88127949&utm_source=google&utm_term=&utm_campaign=Graybar%3EPLA%3ECategory&utm_medium=cpc&utm_content=QEGCy61G|pcrid|49843842170|pkw||pmt|&gclid=CjwKEAjw19vABRCY2YmkpO2OzTsSJAAzEt8sSCue-H0JqJdbmNb92-JSkh_oONy7pXosTz570PwlOhoCYTHw_wcB

Questions:

(a) The 7.5hp compressor has a magnetic start --- will using a "plug in" male into the above receptacle be a problem or should it be hard wired with a cut off switch?

(b) Any problem with "upgrading" the existing "three prong" male plugs on the welders to the 4-wire 50A grounding male connectors ?

(c) I know Arc Fault breakers (now being mandated in many localities) are a pain in the **** with welders, but has anyone had problems with GFCI breakers on welding, air compressor circuits?

 

[theoldwizard1]

The typical plug for welders is a NEMA 6-50.

I don't think there are any outlets/plugs rated for a 7.5 hp motor.

 

[ttpete]

The typical plug for welders is a NEMA 6-50.

I don't think there are any outlets/plugs rated for a 7.5 hp motor.

There are, but you won't find them at Lowe's. At Ford we had receptacles for 240 for heavy portable equipment. I recall an extension cord that was made up of 1-4 SO cable with plug and receptacle to match. 240 was max voltage allowed. Anything over that had to be hard wired.

 

[FrancisJ]

Wouldn't you know it --- the three welders in question all have different input plugs, one a NEMA 6.50P, another a L14-30, and one a NEMA 14-50..................I'm going to "standardize" and run all over a 50A plug, receptacle --- sure wish the Millers and Lincoln Electrics of the world would come up with a "modular" 208/220/230V arrangement.

 

[FrancisJ]

There are, but you won't find them at Lowe's. At Ford we had receptacles for 240 for heavy portable equipment. I recall an extension cord that was made up of 1-4 SO cable with plug and receptacle to match. 240 was max voltage allowed. Anything over that had to be hard wired.

Exactly --- I've seen similar. Thank you.