Assume I have a portable piece of equipment which requires 480V,15A, 3 Phase power, this portable equipment has a 15A circuit breaker disconnect all properly size for it's load. I have a receptical rated 480V, 60A 3 Phase, and this is what I will plug into. Question, What is the (wire) size of the flex cable (10 feet) that I must put on the portable equipment to be allowed to plug into this receptical? Does the cable need to be sized for the 60A service and it's protection, or does code allow me an exception due to the 15A breaker?
Portable plug in equipment
- Thread starter KermodeKT
- Start date
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Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
Is this a listed piece of equipment?
What is the size of the cord and attachment plug on it currently?
What is the size of the cord and attachment plug on it currently?
- Location
- Massachusetts
You will need some over current protection, you cannot supply 15 amp equipment with 60 amps.
This is equipment that is being developed, Think of it as a portable pump with operator interface controls. It is totally self contained and only requiers an electrial service of 480V, 15 Amp, 3 Phase. Where I can plug it in is a 60 Amp Fused disconnect switch with a Hubble 60 amp receptical. As the equipment stands today, there is no cord on it, hence the question of what size to install. Does code allow me to down size the wire (i.e. tap rule)?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
So, replace the fuses with 15a fuses, and the receptacle with a suitable one to match an appropriate cord.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
Larry, maybe you missed this his first post
" I have a receptical rated 480V, 60A 3 Phase"
Kermodekt
I do not understand what you mean by "This is equipment that is being developed"
Developed by whom?
Do you mean you are building this piece of equipment at the jobsite? Is there going to be a listing for this?
I hate to say this, but it sounds more like you are putting together something to satisfy some need and have no real plan, etc...
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
Pierre, I caught that. I'm suggesting replacing the fuses with 15a fuses, replacing the receptacle with one more suitable for the load, and using a cordset to match the receptacle.
If they want to keep the 60a setup, they can place a 15a tap on the 60a feeder, and serve a 15a disconnect and receptacle from that.
It looks like they'd need to use 20a locking devices. I see no 15a 480v receptacle configurations in the NEMA chart.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
Larry
I missed where you mentioned the receptacle replacement. Sorry.
I missed where you mentioned the receptacle replacement. Sorry.
- Location
- Illinois
- Occupation
- retired electrician
If the cord and plug are rated at 60 amps and the load end of the cord is connected to a 15 amp OCPD, I don't really see an issue.
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
That, I believe, was the question: Must he use a 60a cord and plug, or could he use the load's OCPD's rating as protection for a smaller cord?
The plug would have to match the unchanged receptacle, but, would the cord? What if he kept the receptacle (and plug), but used smaller fuses?
- Location
- Illinois
- Occupation
- retired electrician
I don't see anything is 240.5 that would permit the use of a cord with an ampacity of less than 60 amps.
PetrosA
Senior Member
- Location
- Lancaster, Pennsylvania
This may be a stupid question, but if the equipment has a built-in OCPD, what is the difference between using a 14 gauge cord on this 60A circuit and a 16 or 18 gauge cord on a lamp or chandelier from a 20A circuit (which doesn't have built-in OCP)? Wouldn't the cord be considered to be protected by the equipment-side OCPD?
- Location
- Connecticut
- Occupation
- Engineer
Don, I've reread 240.5 several times, and still haven't convinced myself... but what about the last sentence in 240.5(A) - "Supplementary overcurrent protection, as covered in 240.10, shall be permitted to be an acceptable means for providing this protection?"
I think the overcurrent protection provided with the equipment could be acceptable to provide protection to a flexible cord with an ampacity of at least 15.
- Location
- Connecticut
- Occupation
- Engineer
The difference is that the Code has a specific set of rules for fixture wires (NEC 240.5(B)(2).) Eg, on 20A branch circuits - fixture wires can be #18 up to 50ft, #16 up to 100ft, and #14 or larger for an unlimited length.
Open Neutral
Senior Member
- Location
- Inside the Beltway
- Occupation
- Engineer
I suspect he wants to be able to plug it into any one of an number of existing 60A receptacles.
The Brits seem to use fused plugs for this: the ring wiring was fused at 30A, but each appliance plug fuse was for its demand.
The Brits seem to use fused plugs for this: the ring wiring was fused at 30A, but each appliance plug fuse was for its demand.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
210.19, 406.7 and listing of the equipment are most likely items of discussion. As we can see from the above post from the OP, this equipment is under development, or they are building and using it onsite...
Cold Fusion
Senior Member
- Location
- way north
Kerm -
Other than a few exceptions, the NEC neither specifies, nor cares what you plug into a receptacle. The device you are building is not premesis wiring - the NEC does not apply.
I'd guess the facility has a multitude of 480V, 3ph, 60A, "welding receptacles" scattered around. And I'm guessing you want to use which ever receptacle is in the area you need the device in. Pretty normal for industrial areas.
As for any listing concerns, that would depend on the intended use. If you are building hundreds for sale for other customers, maybe listing is a concern.
If you are building a one-off for your company's use, then any listing requirement is up to state law. Most do not require a listing for a one-off piece of cord and plug portable equipment.
As for the cord size, as Dave Luchini and some of the others said, 15A is fine. But it is a design issue.
cf
- Location
- Illinois
- Occupation
- retired electrician
I would think that the supplementary overcurrent protection would have to be on the supply end of the cord.
- Location
- Connecticut
- Occupation
- Engineer
I don't read it that way. I think it says (from memory) supplementary overcurrent protection AT the equipment, or something to that effect. Don't have the code with me, so I can't verify the wording.
kwired
Electron manager
- Location
- NE Nebraska
If this were permantly installed equipment the OP could make a 10 foot 14AWG feeder tap on a 60 amp circuit and land it on the disconnect for his equipment.
The only difference in his situation is the cord and plug everything else is the same. The tap starts in the cord cap and ends in the disconnect in his equipment.
The only difference in his situation is the cord and plug everything else is the same. The tap starts in the cord cap and ends in the disconnect in his equipment.
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