plug

[rswolff001]

So far I haven't gotten an answer for the following question....

Can you put a 60a plug on SO cord rated for 30a, plug it into a 60a receptacle, if the machinery being supplied by the cord has fusing limiting the amp draw to 30a (or less)

I thought this was not acceptable but can't locate anything covering this in the code

Thanks, bob:blink:

 

[lunalilo]

No you cannot. And you haven't not mentioned anything about whether or not the breaker would be 60 amp? But it really wouldn't matter, the only compromise and allowed practice would be to put a much bigger rated gauge wire on the correctly rated plug and receptacle for the correctly rated breaker. There's a reason why the receptacles are rated the way they are so that someone who does not know what they're for or does not know what they're doing doesn't plugin a 60amp machine.

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[lunalilo]

I'm assuming it is a dedicated circuit to? I could almost guarantee it is. And if it is I could almost guarantee that the manufacturer installation manual would also have the correct installation breaker, wire, and receptacle type. If it's not installed correctly they void a warranty all together let alone it would also be installed unprofessionally to say the least.

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[lunalilo]

Section 210. 21 B

Talks about single receptacles on an individual branch circuit not allowed to be rated less than that of the branch circuit.

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[rswolff001]

still no answer

still no answer

yes, its a 60a circuit with a 60a wall mounted hubbel receptacle......the equipment is portable equipment.....and the non plug end is terminated at the disconnects on the machines......each machine has its own SO cord rated correctly for the machine requirements. so no, we can't plug a 60a machine in using the 30a cable....

the machine in question is rated for 30a......and has protection devices in the equipment itself.......the SO cord for this machine is rated for 30a.......and there are no manufacturing installation guidelines. (you'll just have to take my word for it).

so my original question still goes unanswered.......can you put a 60a plug on SO cord rated for 30a? I've been told yes and no, by several different electricians. And my question went completely unanswered in the General Forum. I can't locate anything in the NEC code that prohibits this. Mostly everyone agrees that this would be the same as plugging in any device with a lower current draw than the supply circuit.

Thanks, bob

 

[rswolff001]

receptacle

receptacle

the receptacles are all rated for the supply circuit....as is the plug...all 60a.........there is no reference to whether the SO cord needs to be sized for the machine load or the plug ampacity.

So the answer still doesn't apply I believe.

bob

 

[Little Bill]

So far I haven't gotten an answer for the following question....

Can you put a 60a plug on SO cord rated for 30a, plug it into a 60a receptacle, if the machinery being supplied by the cord has fusing limiting the amp draw to 30a (or less)

I thought this was not acceptable but can't locate anything covering this in the code

Thanks, bob:blink:

Look at 240.5(A) then look at Table 400.5

 

[Adamjamma]

I was always taught that unless you can put a fuse at the plug to protect the voltage to the wire, the wire must be rated for the voltage of the plug. But, did not see that in the codes I just read as noted above. So, not sure. Then again, how do you wire a 20 amp stove and a 20 amp oven from a 50 amp stove outlet and it be fine?

 

[lunalilo]

Hello Bob, if you're fishing for an answer to say yes, the answer isn't fact yes you can and it will work.

But the sad fact is there is supposed to be some type of manual or user manual that comes with the equipment and I guarantee you you'll be able to find it and I guarantee it will suggest the exact type of plug to put on the end of that so cord if it came with it at purchase.

The sad fact is if you put a 60 amp plug on a 30 amp rated s o cord technically speaking it will not overheat as long as your equipment does not short somewhere. That's where the problem lies.

If your equipment ground or shorts or fails of that nature your whole equiptment and the cord could set on fire. This is assuming that the breaker on this circuit is 60 amp.

You wouldn't happen to have the model number of the equipment would you? I'll be glad to triple check to see if we can find a user manual of some nature.

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[lunalilo]

Your problem is a little bit more deeper than trying to see if you can connect a 60 amp plug on a 30 amp or 10 AWG wire s o cord.

It's because if you're connecting a 30 amp piece of equipment that is rated for 30 amps to a 60 amp breaker that is in fact against code.

From what I read too I think you can connect pretty much any type of plug you want as long as it is at least rated for the equipment. But you cannot connect equipment that is rated for less than the dedicated branch circuit. This is not only against cold but it is a severe safety hazard if something shorts.

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[sameguy]

Need more info. at power plants under supervision temp. power and changing fuses you might see anything. As they run under their own rules.
Normally the breaker/ fuse is to protect the wire, if the equipment came from the manufacturer with a 60A on a 30A cord then it would be what it is, if your putting the cord cap on then no.

 

[rswolff001]

update

update

ok guys (or girls) once again......this is portable industrial equipment.....its a standalone mixer with a pump, heater and misc equipment (think of it as a skid on wheels).

Each piece of equipment has its own disconnect as well as fusing and circuit breakers. So no, I can't force feed 60a into the equipment.

There is a tag on the equipment indicating the voltage, phases, and amperage of the equipment. No maximum ampacity circuit call out.

On the one in question, it has cord (15ft?) and a 30a 5 pin plug, 3ph, ground and neutral. The neutral is terminated at the machine but not used past the termination point. Its a standard connector for the manufacturer and allows them to use the same plug as needed for the equipment requirements. This particular piece only requires 480vac, 3ph, 60hz, and the ground.

There is no specific call out for the supply circuit in the manual.

On the wall there is a Hubbel 60a receptacle. Customer requested that I replace the 5pin 30a plug with a 60a unit (without a neutral). NO!!! The neutral is not used at the machine....not now....not ever.....its not there for future additions or expansion.

And its a used piece of equipment that originated in Europe. So even if I could contact the manufacturer, they probably don't have a good grasp of the code requirements in the US.

So is it legal to have a 60a plug on a 30a rated cord, feeding a piece of machinery thats protected at 30a?

thanks, bob:?

 

[rswolff001]

update

update

and my original response to the client was no I couldn't do it without also changing the installed SO cord and possibly the disconnect.

I believe the wiring (including the cord) needs to meet 60a standards up to the first current limiting device (fuse or breaker) in the equipment.

However, I can find no specific code to cover this instance. 240.5(A) appears to, but does it apply to plugs and receptacles or to cords directly connected to a branch circuit?

thanks, bob

 

[jap]

I was always taught that unless you can put a fuse at the plug to protect the voltage to the wire, the wire must be rated for the voltage of the plug. But, did not see that in the codes I just read as noted above. So, not sure. Then again, how do you wire a 20 amp stove and a 20 amp oven from a 50 amp stove outlet and it be fine?

A fuse does not protect voltage to the wire.
Yes the wire must be rated for whatever voltage your using it for.
At times, the tap rules are our friends.

JAP>

 

[retirede]

IMO, once you get past the receptacle outlet, the NEC does not apply other than equipment listing, and following manufacturer’s instructions.

When I was a plant engineer, we did this all the time. Usually the portable equipment was something we fabricated and always had its own fused disconnect. We had 30A twist lock receptacle outlets throughout the shop and our equipment had 12-4 SO cord and 15 or 20 A fuses.

 

[rswolff001]

update

update

jap, I believe he really meant current.....if he meant voltage he shouldn't be wiring anything. Nor answering questions.

retirede, yes I understand many have done this. many have also indicated its wrong. many speed on the highway...doesn't make it legal....IYO 240.5(A) doesn't apply then?

and while i can't locate anything about this....it was always my understanding that the plug ampacity should match the cable ampacity ratings.

I'm not being a hardcase.....I don't want to do something more involved (and costly) if its not necessary.

thanks, bob :dunce:

 

[Adamjamma]

Sorry.. meant amps not volts..lol..l but if you can use 20 amp circuits on fifty amp stove breaker to feed oven and stovetop rather than full range, why not as he states for the 30 amp stuff on the 60 amp circuit? I would rTher use the 60 amp wire until I had a fuse in the system, but...

 

[rswolff001]

update

update

because I'm not downsizing the receptacle, I'm downsizing the wiring.

And again, I agree. I'd rather keep everything rated 60a....however in this case thats a significant cost difference...

thanks, bob :happysad:

 

[jap]

because I'm not downsizing the receptacle, I'm downsizing the wiring.

And again, I agree. I'd rather keep everything rated 60a....however in this case thats a significant cost difference...

thanks, bob :happysad:

Cords have their own set of rules as far as overcurrent protection.

As far as I'm concerned 240.5A indicates flexible cords shall be protected by an overcurrent device in accordance with their ampacity specified in table 400.5A1 AND 400.5A2.

Those tables show (if your talking about the usual SEO or the like type of cord) shows 10 ga. max amperage at 25 or 30.

240.10 indicates the supplementary overcurrent protection your describing that you have in your equipment shall not be used as a substitute for the required branch circuit overcurrent protection.

So, no, if your asking me, your scenario doesn't cut it.

JAP>

 

[retirede]

because I'm not downsizing the receptacle, I'm downsizing the wiring.

And again, I agree. I'd rather keep everything rated 60a....however in this case thats a significant cost difference...

thanks, bob :happysad:

You can’t simply up the SO cord to #4? That’s not an outrageous expense.