The subject is cord connected UPS systems. I have been turning down installations that use cords on the secondary side of a UPS to feed a distribution panel. I have been quoting NEC 400.8(1) that prohibits the use of cords as a substitute for permanent building wiring. What is being proposed is the connection of a UPS to a supply receptacle with a cord and plug and to a distribution panel also using a cord and plug. Does anyone else think this violates NEC 400.8(1)?
UPS connections - NEC 400.8(1)
- Thread starter codeho
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ron
Senior Member
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- New York, 40.7514,-73.9925
Re: UPS connections - NEC 400.8(1)
Does the UPS have a manufacturers installed cord on the output, for a field installed version?
Does the UPS have a manufacturers installed cord on the output, for a field installed version?
- Location
- Lockport, IL
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- Semi-Retired Electrical Engineer
Re: UPS connections - NEC 400.8(1)
I do.
- Location
- Massachusetts
Re: UPS connections - NEC 400.8(1)
First as some know I hate cords.
However many UPS systems are showing up on wheels, I imagine this is to aid in servicing.
That being the case I do not wire portable equipment with hard raceways.
In the past I have used LFMC for this as I hate cords (Did I say that already?
IMO 400.7(10) could trump 400.8(1) and does not require the use of a plug and receptacle.
First as some know I hate cords.
However many UPS systems are showing up on wheels, I imagine this is to aid in servicing.
That being the case I do not wire portable equipment with hard raceways.
In the past I have used LFMC for this as I hate cords (Did I say that already?
IMO 400.7(10) could trump 400.8(1) and does not require the use of a plug and receptacle.
rick hart
Senior Member
- Location
- Dallas Texas
Re: UPS connections - NEC 400.8(1)
I have used a set up like you are talking about to facilitate the maintenance of small UPS (<1500VA)and environmental control cabinet. ie. if the UPS goes bad, swap the cord to the outlet. That would meet the need for flexibility for maintenance.
I don't think having a distribution panel connected by cords are a good idea though except for street festivals. What comes out of the distribution panel anyway, more cords or is it permanent wiring?
I suggest that if the load can be plugged into the UPS, cords are fine. If the load is meant to be the source for a way to breakdown multiple circuits, the UPS is a separately derived source and all requirements for permanent wiring be met
I have used a set up like you are talking about to facilitate the maintenance of small UPS (<1500VA)and environmental control cabinet. ie. if the UPS goes bad, swap the cord to the outlet. That would meet the need for flexibility for maintenance.
I don't think having a distribution panel connected by cords are a good idea though except for street festivals. What comes out of the distribution panel anyway, more cords or is it permanent wiring?
I suggest that if the load can be plugged into the UPS, cords are fine. If the load is meant to be the source for a way to breakdown multiple circuits, the UPS is a separately derived source and all requirements for permanent wiring be met
- Location
- Massachusetts
Re: UPS connections - NEC 400.8(1)
Here is the Insatllation manual .pdf for a common one.
The instructions reference input and output cabling.
How would you suggest wiring rolling equipment like this to the buildings permanent wiring?
[ November 22, 2005, 04:57 PM: Message edited by: iwire ]
Rick the units I see, and have wired with cord are roughly the size of a large file cabinet and mounted on wheels.
Here is the Insatllation manual .pdf for a common one.
The instructions reference input and output cabling.
How would you suggest wiring rolling equipment like this to the buildings permanent wiring?
[ November 22, 2005, 04:57 PM: Message edited by: iwire ]
Re: UPS connections - NEC 400.8(1)
Ron,
No, the UPS systems I've seen on plans have a receptacle outlet. When I've asked for documentation from the manufacturer that shows the unit is listed for this scenario, no one has been able to provide it. I have talked to one manufacturer's "UL Liaison" and he told me that the unit they intended to use had a listed conversion kit that would provide a K.O. and allow the use of a permanent wiring method.
Codeho
Ron,
No, the UPS systems I've seen on plans have a receptacle outlet. When I've asked for documentation from the manufacturer that shows the unit is listed for this scenario, no one has been able to provide it. I have talked to one manufacturer's "UL Liaison" and he told me that the unit they intended to use had a listed conversion kit that would provide a K.O. and allow the use of a permanent wiring method.
Codeho
Re: UPS connections - NEC 400.8(1)
CharlieB, Iwire, and Rick Hart,
Thank you for your input. So far, it sounds like I'm not alone in my interpretation of this section. The installation instructions provided by Iwire indicate that the input and output cables should be installed in conduit.
CharlieB, Iwire, and Rick Hart,
Thank you for your input. So far, it sounds like I'm not alone in my interpretation of this section. The installation instructions provided by Iwire indicate that the input and output cables should be installed in conduit.
Re: UPS connections - NEC 400.8(1)
Have been involved in evolution of similar installations in retail facilities on West Coast.
Goes back to first electronic and computer register system power filtering and backup power supplys. Most retail systems exceeded 1960 watts, 20 amp circuit and owners didn't want to maintain multiple 2 kva UPS(s), so we used 3-4 or 5 kvas and fed a small panel with several 15 amp CBS for the loads. Those early UPSs weren't all that reliable so a cord attachment evolved to allow immediate bypass for retail sales until UPS could be repaired. Probably designed/installed over 1000 systems, again West Coast, CA,OR NV,WA AK,ID,AZ CO,MT, and cord vs hard wire probably up less than 5-8 times. Once inspectors understood intent they usually let it fly.
Have been involved in evolution of similar installations in retail facilities on West Coast.
Goes back to first electronic and computer register system power filtering and backup power supplys. Most retail systems exceeded 1960 watts, 20 amp circuit and owners didn't want to maintain multiple 2 kva UPS(s), so we used 3-4 or 5 kvas and fed a small panel with several 15 amp CBS for the loads. Those early UPSs weren't all that reliable so a cord attachment evolved to allow immediate bypass for retail sales until UPS could be repaired. Probably designed/installed over 1000 systems, again West Coast, CA,OR NV,WA AK,ID,AZ CO,MT, and cord vs hard wire probably up less than 5-8 times. Once inspectors understood intent they usually let it fly.
rick hart
Senior Member
- Location
- Dallas Texas
Re: UPS connections - NEC 400.8(1)
I have seen the input and output wired using tray cable but did not care for that at all. That unit did not even have wheels.
But then again, the question was the use of cords, not cables.
When we last installed a 18KVA UPS on wheels, LFMC was how it was how we did it. Kept lengths as short as possible to allow service to the batteries and UPS.
I have seen the input and output wired using tray cable but did not care for that at all. That unit did not even have wheels.
But then again, the question was the use of cords, not cables.
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