Data/Server Rack Installation Requirements

13 Apr 2007
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United Kingdom
Hi, in the coming months there will be a job which involves installation of a Server Rack. So i was just wondering what kind of requirements are required, and the regulations.
I understand the rack needs to be properly earth bonded, and that it would need its own separate electrical ring circuit, probably at least around 40Amp 6mm cable, along with a 50amp MCB, and RCD setup.. if incorrect please correct me. With probably an industrial 3pin 63Amp plug and socket and a 3 pole isolator, 63Amp because 1 down from that is only 32amp

Cable probably ideally should be 40Amp 6mm cable with a 50 amp mcb and dedicated earth for the Rack.

as at maximum load, the 3 severs which have the 10amp warning sticker alone would add up to 30Amp.

If thats under-rated or over rated any recomendations?

although not at present, the final setup will be anything up to,

2 Swiches, Modem, VPN Firewall

3 or 4 Servers 2/3 of which according to the power supply sticker, at full load use 10 amp each. Because there is a warning sticker on it saying
(It is dangerous if the wall socket is not specified for 250vac/10amp)

and a UPS

and that should allow for sufficient expansion?
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Are you fitting for a company?

Get a spec.

4 servers with switches and routers aint gonna be 50amp.

A 50 amp UPS would not fit in a 19" rack.#

Earth bonding? I would hope the rack is build to the BS. No bonding required.
if there are 3 servers, each 10 amp at full load, that would add up to 30amp wouldnt it?... with a few amp extra for other bits and pieces, so 40Amp cable i would of thought would be required for that, so instead of a 50amp mcb, would 40amp be more ideal?.. i wouldnt of gone much below that with 30 amp worth of servers.

I wouldnt of believed the servers are 30 amp for 3 of them.. but theres a sticker on the power supplies that says

(it is dangerous if the wall outlet is not specified for 10a) which implies full load would be 10amp.
ok, so the first problem I see is a 40A cable protected by a 50A breaker.. see the problem there???

you will need to take into consideration the high earth leakage currents and this is a special installation ( old section 607 in 16'th edition regs book.. )

use 10mm² cable to feed the socket and the earthing requirement is satisfied..
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yea i do see the problem lol, because ideally the cable should be the same as the MCB rating

as for earth bonding not being required it is, it even says it in this post.


because of high earth leakage, and when you have 1000Watt power supplies in these servers, everything needs to be safe
ok, so you recommend using 10mm 53amp cable? to feed the socket?
what sort of servers are these that take 10A each?
The servers, 2 at present with this spec.. 3rd later on. They was custom builds, and are fitted with 1000Watt, Power supplies.

And on the back of them, there is a Yellow Caution sticker, stating that it is dangerous if the wall outlet is not specified for 10amp... 15amp if its 125vac but only 10amp for 250vac.

So the assumption would be.. if the server power supply was under full load, it requires 10amp, and if there is 3 of them.. 30amp between them.

Even if they are never used to full load.. i would of thought the safest thing to do would be to ensure the circuit is still capable. This would also allow for expansion if more servers/devices are added to the rack.. it is 42U afterall
what table are you getting you cable rating from?
10mm² T+E takes 64A clipped direct, while 10mm² armoured takes 67A clipped direct..

either way it's more than the 50A rating of the breaker..

High integrity earthing can be achieved in several ways..

a 10mm² protective conductor is one way. another way would be to use armoured cable and use the armour as a secondary earth path to connect the rack to..
the data is listed in the electrical catalogue, 10mm says 53amp.

so what sized cable and setup would you recommend?
"1000Watt, Power supplies" just over 4.5 amps

Without beating about the bush, you need proffessional advice, as you don't have a clue.

Employ an electrician
i probably will, just wanted advice on the requirements so i could see what is involved.. if its 4.5 Amp why does it say on the power supply 10amp? even says on the specifications on their website. and i know some data racks are shipped with 32Amp industrial 3 pin connectors on the PDUs
because 4.5A is too close to a 5A fuse to be comfortable and prevent nuisance blowing, and 10A is the next readily available size..
Thanks, so really, it dont need much more than an ordinary ring circuit dedicated to that rack, and adequate earthing and isolation.
most racks I've seen come with an internal PDU with a 16A or 32A industrial plug on it..

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