SO Cord

Status
Not open for further replies.
R

rswolff001

Member
Let me ask this question again since I'm getting different answers from different electricians....

Wall mounted 65a receptacle. Portable machinery with fusing. There are several different pieces of equipment ranging from 30a to 60a each with its own SO cabling.

SO cord on the 60a machines is rated for 60a.
SO cord on the 30a machines is rated for 30a.

Can we plug any of the machines into the 60a receptacle (using the correct 60a plug)?
Can I put a plug rated for 60a on SO cable rated for 30a?

and again....all the machinery has its own circuit breakers and fusing.

On a previous post it was indicated I could not....though no one indicated why? Two electricians I spoke with believe it meets code.
No, I haven't pulled up the necessary parts of the NEC book (which I will) but often its not specifically clear.

Any further information is appreciated. And if you can point to the NEC part in question that will also earn at least my gratitude.

Thanks, Bob:(
 
Can this be compared to plugging a 15a device into a 20a receptacle? How about a 40a range into a 50a receptacle? How about a 15a camper plug into a 30a or 50a camper receptacle with an adapter?
 
The engineering rationale behind "device with 30A SO cord connected to a 60A receptacle" would indicate that it's fine; if a short occurs in the tool or cord, the 60A OCPD (breaker) will certainly still trip; the cord won't vaporize (or even heat up) before the breaker trips.

I agree that it's the same as - for instance - plugging a table lamp with 18ga cord to a 20A receptacle/circuit.

It would be different if the device could have load added that would exceed the ampacity of its cord (a power strip comes to mind) but that doesn't seem to be the case here.

SceneryDriver
 
seems plausible to do 30p in 60r, and a 60p in 30r (if it were able to do so).

but what do the install instructions say for the gear? NEC says you must follow those instructions. if the 60a device says "provide a 75a bc" then its violation to put the 60p into anything other than a 75a bc (unless the instructions were faulty, like perhaps there is no 75a ocpd available for the panel).

but using OP logic, why not then just make them all 60a(or more) rated bc's and not worry about what can plug into what (unless the instructions say otherwise)?

the issue described in post #4 is, the 30a cord on a 60a bc somehow does not short 100%, but enough to short 39a worth, so eventually the SO cord burns up, perhaps because 1) its on a 60a ocpd bc, and 2) the gear's internal protection either failed, or, the short was pre gear protection devices.
 
SO Cord

that's what we determined also....still one question open.....can we put a 65a plug onto SO Cord rated at 30a? None of us have ever done something like this. So it would be similar to cut off the 15a plug on your tv, and wire it into a 30a or 40a plug? and then plug it into a 30a or 40a receptacle.

And, I'm not sure. Some of the machines probably came with cords and plugs (the wrong ones) or simply cords. I'm only involved with the last one which has a 5pin 30a plug. The cord is rated at 30a and I was asked to replace the plug with a 65a unit.

thanks, bob :blink:
 
rswolff001 said:
that's what we determined also....still one question open.....can we put a 65a plug onto SO Cord rated at 30a? None of us have ever done something like this. So it would be similar to cut off the 15a plug on your tv, and wire it into a 30a or 40a plug? and then plug it into a 30a or 40a receptacle.

And, I'm not sure. Some of the machines probably came with cords and plugs (the wrong ones) or simply cords. I'm only involved with the last one which has a 5pin 30a plug. The cord is rated at 30a and I was asked to replace the plug with a 65a unit.

thanks, bob :blink:
Click to expand...
well, i suspect not, 400.3 likely prevails here.

even if you did cap 30a SO with a 60a plug, the ocpd needs to be sized accordingly, which is likely way less than your 60a needs of the other gear that would "share" the receptacle.
 
rswolff001 said:
that's what we determined also....still one question open.....can we put a 65a plug onto SO Cord rated at 30a? None of us have ever done something like this. So it would be similar to cut off the 15a plug on your tv, and wire it into a 30a or 40a plug? and then plug it into a 30a or 40a receptacle.

And, I'm not sure. Some of the machines probably came with cords and plugs (the wrong ones) or simply cords. I'm only involved with the last one which has a 5pin 30a plug. The cord is rated at 30a and I was asked to replace the plug with a 65a unit.

thanks, bob :blink:
Click to expand...

Regardless of answers you get here you should contact OSHA, I have always had good luck getting responses from them.

Roger
 
One of my past employers was asked to supply a small (7.5HP, 5.5kW, 460/3/60) wheel mounted hydraulic power unit including controls and a 40 ft. power cord. We were not a UL shop, so farmed out the panel. This needing under 15A, we supplied a 14-4 SO cord. We were then asked to supply a plug to go into their 60A welding receptacles.

We declined and explained why we felt we couldn't legally. Their safety department was asked, and agreed with us. They asked for an option.

Our solution, right or wrong, was a small Hoffman box with 30A fuseholders, a suggestion of 15A time delay fuses, a suitable plug on a 4 or 5 ft 8-4 SO cord and our 40 ft cord going into it.

It worked, but their maintenance department threw our box away and put the welding plug on the 14-4 cable.

If they hadn't paid the bill, I would have wanted to notify osha, but looked the other way.

Was the direct 60A plug connection code compliant? Was my box with fuses satisfactory to be code compliant?

I've read this thread ... and wonder, to some extent, how this compares to a 18-2 SPT cord for a 5W LED below-cabinet lamp plugged into a 20A protected outlet.

I'm not an electrician. I used to pretend to be an (not registered) engineer and designed and supervised construction of (pre-UL508 days) electrical control panels, but am retired.
 
GeorgeB said:
I've read this thread ... and wonder, to some extent, how this compares to a 18-2 SPT cord for a 5W LED below-cabinet lamp plugged into a 20A protected outlet.
Click to expand...

400.3

the LED example is not the same as what OP is asking.

one would certainly not install NEMA L5-30r's everywhere to accommodate two 30A mobile mixers and then replace all other NEMA-5 cap cords with a L5-30 plugs.

SO cord is not premise wiring, so plugging in 18ga vacuum or lamp cord to 20A bc is acceptable. but for OP the question is rooted around more of permanent device that uses SO cord to the outlet.
 
Status
Not open for further replies.
Top