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Motor duty 6-50 socket?

lucky7

Titanium
Joined
Sep 6, 2008
Location
Canada
At home want to have a 50 amp 2 pole breaker in main panel supply a 60amp non fused switch to turn on and off a 15 hp 230 volt GWM rotary phase converter. Using #6/2 copper. Ideally would like a 6-50 socket at load end of this switch so I can also use for welder on occasion. Stumbled onto a discussion about 6-50‘s not being appropriate for motor loads. Over my pay grade. Is this true? Work around?
 
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BT Fabrication

Stainless
Joined
Nov 3, 2019
Location
Ontario Canada
any plug can be easily a point of failure.
simple solution.
direct wire the RPC
then run off another wire from pull down switch and have a seperate plug for a welder. the rpc will have power when on, but won't go through as the rpc isnt on and the contactor wont be closed inside the rpc control cabinet.
 

sfriedberg

Diamond
Joined
Oct 14, 2010
Location
Oregon, USA
lucky7, a plug/receptacle of adequate (NEC says 125% of full-load current, not locked-rotor current) ampacity can handle a motor just fine. However, it's not a good "disconnecting means". Meaning, don't turn the motor on and off by plugging it in or unplugging it. If your switch is 15HP rated, and you always use the switch to disconnect the receptacle before messing with the plug, you're golden. (I am assuming you would have either the phase convertor or the weldor plugged in at any given time, but not trying to run both at the same time.)
Having said that, I would double-check your 50A breaker assumption! That does not sound kosher for a 15HP single-phase motor load! I am using a 70A breaker for a 10HP Phase Perfect converter, which is both less HP and less inrush load than your planned rotary converter.
I would also recommend you put in a fused disconnect instead of an unfused one, with time-delay (slow-blow) fuses rated at 125% of the motor full-load current. The breaker is to protect your wiring. The fuse is to protect your motor.
 

lucky7

Titanium
Joined
Sep 6, 2008
Location
Canada
Yeah, 50 amp breaker seemed low to me as well, but that’s what GWM recommends.

Disconnecting 50 amps 220volts by plug sounds too close to a really bad day. Yes, that’s why the switch.
 

Superbowl

Hot Rolled
Joined
Feb 12, 2020
Just put in a small sub panel with 6-8 breaker slots feeding your switch and outlet.
 

jim rozen

Diamond
Joined
Feb 26, 2004
Location
peekskill, NY
Late to the party but you can buy a better quality 50amp cord connector set from mcmaster carr. It's non NEMA and not cheap, being used for shore power - boats and RVs. Again not for use to disconnect under power. But a super connector.
 

lucky7

Titanium
Joined
Sep 6, 2008
Location
Canada
Thanks, Jim. I knew about 100 and 200 amp ship to shore connectors (pricey!) but didn’t know about smaller amp versions. And have seen some ‘interesting’ connectors on various overseas military bases in a past life, but that’s a little OT.

Sueprbowl, don’t need a subpanel, have plenty of space and capacity in main panel.

Waiting on a friend who knows more about rotary converters than me to give second opinion on amps to feed this one. Largest load will be a clutch head 7.5 hp lathe, and won’t ever have more than 8 hp total running at one time.
 

sfriedberg

Diamond
Joined
Oct 14, 2010
Location
Oregon, USA
Regarding jim rozen's suggestion, I use IEC 60309 connectors at the fused disconnects in my shop for the larger machines. The connectors are indeed super, but the plugs are as big as wine bottles. (That's not an exaggeration. Someplace I've got a picture I took of a plug and a bottle standing next to each other on my kitchen table.)
 

JST

Diamond
Joined
Jun 16, 2001
Location
St Louis
Plugs are accepted as a "disconnection means" in most cases.

Not as a switch, but as a positive disconnect that will not allow power through when disconnected.

When used as rated, they are not employed as switches. And when used outside their ratings, they are not approved.
 

rons

Diamond
Joined
Mar 5, 2009
Location
California, USA
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SAF

Stainless
Joined
Jul 20, 2014
Location
MI USA
Lucky : Over my pay grade. Is this true? Work around?
WDK_WiringDevices_PinSleeve_IECPinSleeve_300.jpg


A Brief Guide to Pin-and-Sleeve Devices

Arrow Hart Pin and Sleeve devices

Hubbell Pin & Sleeve

McMaster Electrical Connectors

ebay pin and sleeve
 
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Superbowl

Hot Rolled
Joined
Feb 12, 2020
Sueprbowl, don’t need a subpanel, have plenty of space and capacity in main panel.


I know you don't "need" a sub panel. Perhaps I was not clear. The breakers in the sub panel can be your local on and off switches. One 50 amp breaker to turn the phase converter on and off. And when the phase converter is turned off, you can switch the other breaker on to put power to the outlet for your welder. Breakers make good cheap high amperage switches.
 

JST

Diamond
Joined
Jun 16, 2001
Location
St Louis
The item Rons linked is specified and rated to interrupt full current. That means it can be used as a disconnect in any definition.

Don't know but doubt it is rated for any inrush when plugged IN. So not suitable for that.

UL is indicated at top of catalog page, and in listing part of spec page
.
 
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Superbowl

Hot Rolled
Joined
Feb 12, 2020
I fat fingered that quote. What I was saying was:


I know you don't "need" a sub panel. Perhaps I was not clear. The breakers in the sub panel can be your local on and off switches. One 50 amp breaker to turn the phase converter on and off. And when the phase converter is turned off, you can switch the other breaker on to put power to the outlet for your welder. Breakers make good cheap high amperage switches.

I have a 50 amp outlet on the wall near my garage sub panel. 95% of the time my hot tub is plugged into it. When I need to run my 7.5 hp compressor I shut off the 50 amp breaker, unplug the hot tub, plug in the compressor, and flip the breaker on. I also use the same outlet for my welder. It does triple duty.
 

JST

Diamond
Joined
Jun 16, 2001
Location
St Louis
I fat fingered that quote. What I was saying was:


I know you don't "need" a sub panel. Perhaps I was not clear. The breakers in the sub panel can be your local on and off switches. One 50 amp breaker to turn the phase converter on and off. And when the phase converter is turned off, you can switch the other breaker on to put power to the outlet for your welder. Breakers make good cheap high amperage switches.

........................
You can often get away with that, but standard breakers are not rated for a "lot" of operations, as with "switch duty". There are breakers rated for that, but they are not as common and may not be available for your panel.
 

Superbowl

Hot Rolled
Joined
Feb 12, 2020
You can often get away with that, but standard breakers are not rated for a "lot" of operations, as with "switch duty". There are breakers rated for that, but they are not as common and may not be available for your panel.
If you are going to use it a LOT then there are certainly better, but much more expensive ways to go. You will however get a reasonable amount of use from a standard breaker and they can, if necessary, be replaced easily for little money.
 

BT Fabrication

Stainless
Joined
Nov 3, 2019
Location
Ontario Canada
If you are going to use it a LOT then there are certainly better, but much more expensive ways to go. You will however get a reasonable amount of use from a standard breaker and they can, if necessary, be replaced easily for little money.
60A pull down switches are only $100 or so. actually designed for this and not a breaker.
 

jim rozen

Diamond
Joined
Feb 26, 2004
Location
peekskill, NY
Thw one rons linked to is the exact connector I use at work, it's non NEMA but a tremenously well-built twist-lock set. Highly reccomend.
 

Superbowl

Hot Rolled
Joined
Feb 12, 2020
60A pull down switches are only $100 or so. actually designed for this and not a breaker.
Yes but he would need two, one for the welder and one for the rpc.

I don't think the code would allow him to run two non- fused 60 amp switches just from a junction box. Can any expert sparkies out there tell us for sure if this is allowable?
 








 
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