Violant of 240.6?

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rsherrard

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Let me start by saying I am not a "power" guru... We are in the process of building out a few new server racks, and appear to have run into a "code" issue per the inspector. In each of my rack locations, I am pulling in (2) 208 3phase 60A circuits, per manufacture specs:

http://h18004.www1.hp.com/products/quickspecs/12118_na/12118_na.html

On the panel / breaker side, we have side the breaker to 60A? the inspector however is saying because the UL plate on the PDU says 48A, that the break should be sized @ 50, not 60. HP however is suggesting per spec we size the circuit to 60A, not 48A.

Does this make sense?

Rob
 
Server racks are continuous loads.

Per 210.20(A) continuous loads must be supplied with a branch circuit with a rating at least 125% of the continuous load.

48 amps x 1.25% = 60 amps.

I would say the correct size breaker is a 60 with at least 6 AWG copper conductors.
 
interesting... this is what we've done; however the insector seems to think we're wrong, because we should have sized @ 50, the next size up from 48.

Rob
 
It sounds like your inspector is interpreting the PDU nameplate like the ones on air conditioning units.

A/C units specify the maximum amps of the circuit which typically include any adjustment factors for continuous loading so they get the next standard breaker (unless the nameplate says differently).

PDUs nameplates usually are listed with the actual full load amp draw of the equipment and must be adjust as mentioned by Bob.
 
So is it safe to assume that by sizing these to 60A, was the correct thing to do... give the UL plate says 48A max on the PDU?

Rob
 
rsherrard said:
So is it safe to assume that by sizing these to 60A, was the correct thing to do... give the UL plate says 48A max on the PDU?

Rob
Click to expand...

I think if you look closely, the NP is stating the maximum draw, not the maximum OCPD size.

Is there a maximum BC OCPD size?
 
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Here's a snip on the PDU spec...

Half Rack Vertical PDU Models
Models S348
Input ratings
Voltage
(VAC)
200-240V 60/50Hz 3U Delta
Current (Amps)
Branch Circuit Requirements 208V, 3U, 4-wire, 60A
Input Plug/Cord Rating IEC309 3 Pole, 4 wire, 250VAC, 60A
De-Rated 48A
Output ratings
Voltage (VAC) 200-240V 60/50Hz 1U
Current (Amps)
Outlet rating C20 16A
Load segment L6 20A
L5 20A
L4 20A
L3 20A
L2 20A
L1 20A
Power (kVA)
Per Line Cord 17.3 kVA
PDU Total 17.3 kVA
Number of Outlets
Load Segment /
Line Cord
C19 6 (2 per segment)
 
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