Article 645 Exception for Article 685

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barclayd

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Colorado
I assume that Article 645.11(1) applies mainly to small/medium UPS Systems that are installed on a raised floor.
Would it also apply to a small (1kva) 'Standby Power Supply' that is installed as an integral part of a piece of I.T. Equipment? It is a RAID Storage Processor, and the power supply protects the data in case of a power loss. It is active for up to 90 seconds after loss of power, and allows time to write cache data to a disk.
Generally, we do not allow small, rack-mounted UPS Systems to be installed on our Raised Floors. We provide redundant UPS power to all data processing loads. This particular device is an integral part of the data processing equipment.
I would appreciate any comments, but am especially looking for replies from those experience in raised floor operations, and those familiar with Article 645.
thank you
 
If you are in the unfortunate position, to have to comply with the optional requirements of Article 645 (because you need the more relaxed wiring requirements), then any UPS >750VA must comply with the EPO requirement.
I've heard of one installation, where the engineer of record (I wont tell you who that was :) ) convinced the AHJ that the installation qualified under the provisions of 685, but it was a huge stretch.

My recommendation is to try not to use the more lenient wiring rules of 645 in your IT equipment room, and then you don't need the hassle of any of the 645 requirements/pre-requisites.


Edited for a 10^3 mistake in my VA quote from the code.
 
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Ron
Thanks - unfortunately, it is an existing room, in service for over 20 years, and would be almost impossible to 're-classify'.
We will probably stand firm and not allow it, but will probably get over-ruled by 'Operational Considerations'. (that means the equipment is already on-site and ready to be installed).
 
ron said:
If it shows up, you will have to connect it to the existing EPO system since it is >750VA.
Click to expand...
The data processing equipment rack is powered from the building UPS which is controlled by the EPO. Unfortunately, the 'Standby Power Supply' will continue to operate until any cached data is stored, up to 90 seconds. It is not configured to be connected to the EPO.
I think this type of equipment was designed primarily for non-raised floor environments.
 
Raised floor or not, the disconnecting means (EPO) still apply.
Luckily, most AHJ's do not inspect to the rack level, IF they are called for this type of inspection at all.
 
ron said:
Raised floor or not, the disconnecting means (EPO) still apply.
Luckily, most AHJ's do not inspect to the rack level, IF they are called for this type of inspection at all.
Click to expand...
I was thinking more of a comm. closet or a LAN room where 645 does not apply. You're right - I don't think I've ever seen an inspector look into an equipment rack on a raised floor.
db
 
Ron
Well, we've drawn our line in the sand. We have notified the customer that the equipment will not be allowed unless they reconfigure it without the Standby Power Supply. 645.11(2) is pretty clear. Thanks for your insight.
db
 
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