NEC related issues within a rack/panel
NEC related issues within a rack/panel
(OP)
Lets say we have an equipment rack, and inside this rack we have a bunch of equipment (ethernet/fiber switches, etc), each requiring AC power. So within this rack is a primary power dist unit, and mulitple secondary units. Think of the secondary units being smart power strip where the outlets can be controlled via rs232.
The primary unit takes in a 3phase power (208Y) and gives 3 legs of 120VAC, each being sent thru a breaker then on to the secondary power strips. So technically we have a bunch of mini branch circuits.
So looking thru the NEC codebook, the majority of the articles deal solely with wiring in a dwelling, or wiring feeding to an equipment rack but doesnt't directly talk to wiring INSIDE the rack. So if we have a 20A circuit breaker on the primary distribution panel inside the rack, where it is rated for 100% load, then a 20A IEC recepticle where the secondary power strip then uses a 20A cable and plug to tie into that, does each of the items need to be derated 80%? Or does this ONLY apply to the main branch feeding the primary power unit in the rack. I tend to think that anything inside the rack does not require any derating.
Comments please?
The primary unit takes in a 3phase power (208Y) and gives 3 legs of 120VAC, each being sent thru a breaker then on to the secondary power strips. So technically we have a bunch of mini branch circuits.
So looking thru the NEC codebook, the majority of the articles deal solely with wiring in a dwelling, or wiring feeding to an equipment rack but doesnt't directly talk to wiring INSIDE the rack. So if we have a 20A circuit breaker on the primary distribution panel inside the rack, where it is rated for 100% load, then a 20A IEC recepticle where the secondary power strip then uses a 20A cable and plug to tie into that, does each of the items need to be derated 80%? Or does this ONLY apply to the main branch feeding the primary power unit in the rack. I tend to think that anything inside the rack does not require any derating.
Comments please?





RE: NEC related issues within a rack/panel
Typically, derating is not necessary on conductors and protective devices within an enclosed piece of equipment. That is why you will often find smaller conductors inside of a device than you would use to hook it up.
With all that said, ultimately the final authority is the inspector who sees it!
"Venditori de oleum-vipera non vigere excordis populi"
RE: NEC related issues within a rack/panel
jraef sized it up well. One aside—IEC320 connectors have several ratings, but the most common 10-ampere pattern is listed with two temperature ratings… ‘C13/C14’ 70°C versus ‘C15/C16’ 120°C Limited description at http://www.encyclopedia4u.com/i/iec-connector.html
RE: NEC related issues within a rack/panel
RE: NEC related issues within a rack/panel
Looks like it. From the link, C15 cord will fit the C14 receptacle, but the C13 will not fit the C16.
RE: NEC related issues within a rack/panel
According to my book they are available in 6, 10, 16 and 20A versions which all look identical
RE: NEC related issues within a rack/panel
RE: NEC related issues within a rack/panel
I think the 6A and 10A IEC320 cords are pretty much identical physically. The 16A version is visibly bigger, but has a similar appearance to the 6A and 10A types. I've not encountered a 20A type (yet).
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