Emergency Power for UPS

[Turk1957]

We have a client that currently utilizes numerous small, stand-alone, rack mounted UPS units for IT backup (Cisco Switches, Power Supplies, etc..). These are serving critical system loads and they want to provide Emergency Power in the event of a power failure. Since UPS runtime decreases drastically dependent on the load, they are looking at providing something with a much longer duration? They have capacity in the Emergency Generator they utilize for Life-Safety, but is that really the best approach, to feed UPS units from an Emergency Generator?

 

[petersonra]

We have a client that currently utilizes numerous small, stand-alone, rack mounted UPS units for IT backup (Cisco Switches, Power Supplies, etc..). These are serving critical system loads and they want to provide Emergency Power in the event of a power failure. Since UPS runtime decreases drastically dependent on the load, they are looking at providing something with a much longer duration? They have capacity in the Emergency Generator they utilize for Life-Safety, but is that really the best approach, to feed UPS units from an Emergency Generator?

I have seen UPS units fed from generators before to increase the hold up time. I don't know if they were on an "emergency" generator or not. I think it is allowed, but personally I am a little suspicious of trying to tack on a bunch of new stuff to an existing generator.

 

[augie47]

You might want to take a look at 701.6
I agree with Bob.,... proceed with caution.

 

[iwire]

We have a client that currently utilizes numerous small, stand-alone, rack mounted UPS units for IT backup (Cisco Switches, Power Supplies, etc..). These are serving critical system loads and they want to provide Emergency Power in the event of a power failure. Since UPS runtime decreases drastically dependent on the load, they are looking at providing something with a much longer duration… They have capacity in the Emergency Generator they utilize for Life-Safety, but is that really the best approach, to feed UPS units from an Emergency Generator?

If it is a true NEC article 700 emergency system you can't just add optional loads to it regardless of capacity. Those 'critical loads' are not critical to the NEC and are considered 'optional standby loads' as covered by article 702.

It might be possible to add these loads to the generator if you add a second ATS and a new panelboard supplied from that ATS to feed your optional loads.

 

[eHunter]

If it is a true NEC article 700 emergency system you can't just add optional loads to it regardless of capacity. Those 'critical loads' are not critical to the NEC and are considered 'optional standby loads' as covered by article 702.

It might be possible to add these loads to the generator if you add a second ATS and a new panelboard supplied from that ATS to feed your optional loads.

+1
AND there is adequate unused generator capacity to supply the new loads.

If the UPS powered equiupment also supports voice communications, paging and/or mass notification equipment it may very well be classed as critical or emergency.

 

[petersonra]

It might be possible to add these loads to the generator if you add a second ATS and a new panelboard supplied from that ATS to feed your optional loads.

Sounds like more trouble than it is worth.

A decent NG gas fired generator just for the IT stuff is probably a more cost effective approach.