Cord and plug legnth?

[electricaldoc]

Does any one know what the maximum length for a cord and plug on industrial three phase equipment?
At work we have some 480v three phase 60a cords that my span 75 to 100 ft in order to keep from use of extension cords. Is this legal?

 

[ron]

Re: Cord and plug legnth?

There is no limit established in the NEC. The listing agency generally has a limit. For example, most cord and plug connected stuff have a 6' cord. Listed IT equipment in some caes can have 15' cords. Industrial equipment may not have that limit. Also if the cord is added after independent testing agency (UL in some cases) inspection, the cord might not be part of the listing.

 

[gene]

Re: Cord and plug legnth?

If you're using the cord and plug as the required disconnecting means for machinery, with-in sight limits the distance to 50 feet.

 

[petersonra]

Re: Cord and plug legnth?

Originally posted by gene:
If you're using the cord and plug as the required disconnecting means for machinery, with-in sight limits the distance to 50 feet.

NFPA79 5.3.2 (6) limits the use of cord and plugs as disconnects to a maximum motor load of 2 HP. Since its machinery, it is likely subject to NFPA79.

The size of the plug makes me wonder what HP it is.

 

[charlie b]

Re: Cord and plug legnth?

This seems to me to be a violation of 400.8(1) (2002 version). Any comments?

 

[iwire]

Re: Cord and plug legnth?

Originally posted by charlie b:
This seems to me to be a violation of 400.8(1) (2002 version). Any comments?

I agree as long as the equipment is not on wheels or otherwise mobile.

 

[roger]

Re: Cord and plug legnth?

As far as plugs being allowed for large motor disconnects Meltric makes disconnect rated plugs for some larger motors. See their motor connection info.

Roger

 

[petersonra]

Re: Cord and plug legnth?

Originally posted by iwire:

Originally posted by charlie b:
This seems to me to be a violation of 400.8(1) (2002 version). Any comments?

I agree as long as the equipment is not on wheels or otherwise mobile.

400.8 Uses Not Permitted. Unless specifically permitted in 400.7, flexible cords and cables shall not be used for the following:
(1) As a substitute for the fixed wiring of a structure

Seems to me that some of the other exceptions might apply. Especially the vibration issue.

 

[petersonra]

Re: Cord and plug legnth?

Originally posted by roger:
As far as plugs being allowed for large motor disconnects Meltric makes disconnect rated plugs for some larger motors. See their motor connection info.

Roger

that would be fine it not a machine covered under NFPA79. if it is, and the motor load exceeds 2hp, you are not allowed to do it.

a standalone pump would seem to qualify for this, or a fan, something like that.

 

[iwire]

Re: Cord and plug legnth?

Originally posted by petersonra:
Seems to me that some of the other exceptions might apply. Especially the vibration issue.

I suppose it could be, there is a lot of room for judgment calls in Article 400.

It just strikes me you do not normally need 75' to 100' of cord to prevent transmission of vibration or to allow frequent interchange.

But that is just a personal opinion.

 

[iwire]

Re: Cord and plug legnth?

Meltrics are UL listed as manual motor controllers, the catalog I have shows them rated up to 20 HP

 

[roger]

Re: Cord and plug legnth?

Petersonra, it could be a motor for anything, conveyors, augers, turbines, chiller fans evaporator fans etc....


Roger

 

[plugman]

Re: Cord and plug legnth?

I have a couple of comments:

Meltric has devices rated up to 60hp at 480V.

There are some proposed changes in the works to get rid of the 2hp limit in NFPA 79 as long as the plug and receptacle being used are switch rated.

100 ft does seem fairly excessive for industrial equipment, but 400.7(6)&(8) appear to leave some room for interpretation. Perhaps if electricaldoc could let us know what the equipment is and what it does, a better evaluation could be made.