Safety Factor on a 50 Amp Straight Blade Plug

continuous rated service and right along with this most plugs are junk. There are some good ones but to be safe never count on more than 50% using rating. Especially for continuous service. The best of them fit well and this is apparent when you use them. Along with all this you need good receptacles and preferably the same barnd. Hubbell and better. Twice the money almost everytime. For 50 Amps I would uese 100 Amp rated plugs and if not the largest rating you can afford and have space for. Especially for motors and other inductive loads.

Bob AZ

Just thought I'd chime in and support Bob's thinking. Go someplace where such a plug/receptacle is in use and feel it. You will most likely note that it's already getting hot. And age doesn't make things better!!!!!

Pete Stanaitis

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Bob AZ wrote:

I think you guys are absolutely bonkers on this one. If they underbuilt plugs so they got hot and started a fire, they would get their asses sued off.

Grant

spaco wrote:

Probably true. But they certainly do underbuild them so they get hot at full load, based on touching plugs that have been run at full load for several hours or longer. Not flaming, but not cool, either. And that means that they are adding voltage drop & power loss you could do without to the circuit. ie, if, as will tend to be the case on a cost & lawyer-driven basis, the plug is just good enough to not catch fire at full load, it can still get plenty hot.

Cleaning the blades on the plug can also help, depending how cruddy those are. Cleaning the socket contacts is a bit trickier, and can have detrimental side effects.

I use the typical 50 amp dryer/stove 3 bladed connectors on both my big welders. Even after running long beads with 5/16 rod at 150 or more amps..it takes a rather long time for them to start heating to anything beyond warm

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

Unless you are running a wire feeder with 1/16" wire at big amps..its unlikely you are going to burn one out.

Gunner

"Pax Americana is a philosophy. Hardly an empire. Making sure other people play nice and dont kill each other (and us) off in job lots is hardly empire building, particularly when you give them self determination under "play nice" rules.

Think of it as having your older brother knock the shit out of you for torturing the cat." Gunner

My experience has been that the weakest link in that area is a crappy socket. A lot of the cheaper ones use only the edge of the flat metal for contact on the plug (male) blade. Causes a lot of overheating, which makes the already poor contact even worse. A good socket will contact the entire width of the blade. Hubbell twist-locks are the way to go for higher current use, but at $20 - $30 each, not too attractive. As with Gunner's comment, 50A range plugs have served me quite well, even at full rated current.

Joe

Bob AZ wrote:

Let's remember that the 150 Amp welder is not doing 150 Amps at the input where it is plugged in. The 150 Amps is the output at considerably lower voltage.

Nominally the 50 Amp oven/stove connector/plug is perhaps drawing 20 amps about 8KW which is 4 burners on my stove. And the stove/oven load is resistive. Not inductive as welders are.

Bob AZ

I've certainly noticed that plugs on high-powered devices get warm. Within the last year I've found two plugs (one on an electric fire, one on a hot air gun) which have got alarmingly hot. When I opened them up I found that the neutral screw terminal was several turns loose. My father wired both these plugs 15 or 20 years ago and he's convinced that the screws were originally tight. It seems that the warming had slowly allowed the screws to loosen.

Chris

To get over 50 amp device in a plug or receptacle, you are going to have to use a pin and sleeve style industrial device. We just jumped into the few hundred dollar range now. Why not just hard wire it to a fused disconnect switch and be done with it?

I've used 300 Amp in line Hubble three phase 5 wire connectors. You have to eat good to carry more than one around. Lots of copper! One end was hard wired into the panel (code). (That was 300 amps per leg!) - the wire - It was a troubling concept but it taught us to be different designers.

Martin

Are you using those plugs on the power input side, or on the connections to the welding rod? 150 amps to the rod is *not* going to draw 150 amps from the wall.

Enjoy, DoN.