Hi all,

I'm building a computer server farm, network switch rack and
TV/Sat/Radio headend in my loft. All of these gadgets need 240 volt
power via 13amp plugs.

This means lots and lots of double sockets. :-)

I'm planning on putting in a 32A RCBO in the CU to power all this kit in
the loft via suitable wiring.

The reason for a separate RCBO is to ensure high power availability so
that faults elsewhere in the house do not kill power and hence cause
data corruption in the computer servers.

Now, I have acquired some 2nd hand bench power strips that are basically
white plastic trunking with double sockets inserted. They are wired in a
ring main fashion within the trunking and had a RCBO in at one end.

See https://www.dropbox.com/s/562yp1r27v...Close%20up.JPG and

https://www.dropbox.com/s/kfcvrg71q9...mal%20view.JPG

I intend to modify all these by putting in as many double sockets as the
trunking allows which will be 10 double sockets over a length of 2 metres.

This entire assembly will then be fixed to the loft gable end wall and
then provide a fixed wired cable from this assembly back to the CU.

This will then power all my kit.

Now my questions:

Should I use a single run of 4mm2 cable run back to the 32A RCBO or
should I use 2.5mm2 T&E in a ring main fashion as per normal practice
for ring main sockets?

Will all this be compliant with wiring regs such as socket spacing &
density?

Regards,

Stephen.

On Wed, 05 Dec 2012 21:13:57 +0000, Stephen H wrote:

I'm building a computer server farm, network switch rack and
TV/Sat/Radio headend in my loft. All of these gadgets need 240 volt
power via 13amp plugs.

This means lots and lots of double sockets. :-)

Do they have to be 13A plugs? Can you not use IEC connectors and a rack
mounted PDU or even an IEC distribution strip?

I guess you have a number of wall warts though. When I do the
server/comms/head end here there won't be any wall warts just a beefy 12v
PSU and fused distribution to the various bits of kit. If I need a
different DC voltage a small DC-DC converter will provide that.

I'm also sort of surprised that you need a 7kW+ supply, unless you have
seriously powerful server farm. In which case I assume half of the 7kW is
for the aircon to keep the loft cool in the winter. In summer you'll
probably need all 7kW to keep the kit cool, lofts get damn hot in the
summer... It might not be the best place to have electronics.

--
Cheers
Dave.

"Dave Liquorice" wrote in message
ll.co.uk...
On Wed, 05 Dec 2012 21:13:57 +0000, Stephen H wrote:

I'm building a computer server farm, network switch rack and
TV/Sat/Radio headend in my loft. All of these gadgets need 240 volt
power via 13amp plugs.

This means lots and lots of double sockets. :-)

Do they have to be 13A plugs? Can you not use IEC connectors and a rack
mounted PDU or even an IEC distribution strip?

I guess you have a number of wall warts though. When I do the
server/comms/head end here there won't be any wall warts just a beefy 12v
PSU and fused distribution to the various bits of kit. If I need a
different DC voltage a small DC-DC converter will provide that.

I'm also sort of surprised that you need a 7kW+ supply, unless you have
seriously powerful server farm. In which case I assume half of the 7kW is
for the aircon to keep the loft cool in the winter. In summer you'll
probably need all 7kW to keep the kit cool, lofts get damn hot in the
summer... It might not be the best place to have electronics.

The above is true. You really need to insulate the roof (sloping bits) if
you are going to
do this. The temperature up there could hit 40 degrees in Summer otherwise.
You might consider the use of mulitgang sockets.
http://www.amazon.co.uk/Surge-protec.../dp/B000MWX9FY

On 05/12/2012 21:13, Stephen H wrote:
Hi all,

I'm building a computer server farm, network switch rack and
TV/Sat/Radio headend in my loft. All of these gadgets need 240 volt
power via 13amp plugs.

This means lots and lots of double sockets. :-)

I'm planning on putting in a 32A RCBO in the CU to power all this kit in
the loft via suitable wiring.

The reason for a separate RCBO is to ensure high power availability so
that faults elsewhere in the house do not kill power and hence cause
data corruption in the computer servers.

Now, I have acquired some 2nd hand bench power strips that are basically
white plastic trunking with double sockets inserted. They are wired in a
ring main fashion within the trunking and had a RCBO in at one end.

See https://www.dropbox.com/s/562yp1r27v...Close%20up.JPG and

https://www.dropbox.com/s/kfcvrg71q9...mal%20view.JPG

I intend to modify all these by putting in as many double sockets as the
trunking allows which will be 10 double sockets over a length of 2 metres.

This entire assembly will then be fixed to the loft gable end wall and
then provide a fixed wired cable from this assembly back to the CU.

This will then power all my kit.

Now my questions:

Should I use a single run of 4mm2 cable run back to the 32A RCBO or
should I use 2.5mm2 T&E in a ring main fashion as per normal practice
for ring main sockets?

Will all this be compliant with wiring regs such as socket spacing &
density?

In the grand scheme of things, 32A seems a little excessive for the
expected load. While you may have lots of devices, the chances of them
drawing more than a few amp in total seems remote. Personally I would go
for 16A as more than adequate unless you really are running lots of
servers.

Given your loads are typically going to be IT kit and similar stuff with
lots of SMPSUs and mains input filters, you are potentially going to
have a circuit with normally high earth leakage currents. That suggests
you should be using high integrity earthing practices - which mandates a
ring connection on the CPC anyway. So a 2.5mm^2 ring circuit would
probably be the simplest way of doing this. Use sockets that have two
earth terminals, and wire using both.

The wiring regs are silent on socket spacing. The only density limit is
the floor area covered by each circuit - 100m^2 so not relevant in this
case.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/

Isn't this lot going to make the loft rather hot escpecially in the summer?

Brian

--
From the Sofa of Brian Gaff Reply address is active
"Stephen H" wrote in message
...
Hi all,

I'm building a computer server farm, network switch rack and TV/Sat/Radio
headend in my loft. All of these gadgets need 240 volt power via 13amp
plugs.

This means lots and lots of double sockets. :-)

I'm planning on putting in a 32A RCBO in the CU to power all this kit in
the loft via suitable wiring.

The reason for a separate RCBO is to ensure high power availability so
that faults elsewhere in the house do not kill power and hence cause data
corruption in the computer servers.

Now, I have acquired some 2nd hand bench power strips that are basically
white plastic trunking with double sockets inserted. They are wired in a
ring main fashion within the trunking and had a RCBO in at one end.

See https://www.dropbox.com/s/562yp1r27v...Close%20up.JPG and

https://www.dropbox.com/s/kfcvrg71q9...mal%20view.JPG

I intend to modify all these by putting in as many double sockets as the
trunking allows which will be 10 double sockets over a length of 2 metres.

This entire assembly will then be fixed to the loft gable end wall and
then provide a fixed wired cable from this assembly back to the CU.

This will then power all my kit.

Now my questions:

Should I use a single run of 4mm2 cable run back to the 32A RCBO or should
I use 2.5mm2 T&E in a ring main fashion as per normal practice for ring
main sockets?

Will all this be compliant with wiring regs such as socket spacing &
density?

Regards,

Stephen.

Stephen H wrote:

Hi all,

I'm building a computer server farm, network switch rack and
TV/Sat/Radio headend in my loft. All of these gadgets need 240 volt
power via 13amp plugs.

This means lots and lots of double sockets. :-)

I'm planning on putting in a 32A RCBO in the CU to power all this kit in
the loft via suitable wiring.
The reason for a separate RCBO is to ensure high power availability so
that faults elsewhere in the house do not kill power and hence cause
data corruption in the computer servers.

Now, I have acquired some 2nd hand bench power strips that are basically
white plastic trunking with double sockets inserted. They are wired in a
ring main fashion within the trunking and had a RCBO in at one end.

See https://www.dropbox.com/s/562yp1r27v...Close%20up.JPG and

https://www.dropbox.com/s/kfcvrg71q9...mal%20view.JPG

I intend to modify all these by putting in as many double sockets as the
trunking allows which will be 10 double sockets over a length of 2 metres.

This entire assembly will then be fixed to the loft gable end wall and
then provide a fixed wired cable from this assembly back to the CU.

This will then power all my kit.

Now my questions:

Should I use a single run of 4mm2 cable run back to the 32A RCBO or
should I use 2.5mm2 T&E in a ring main fashion as per normal practice
for ring main sockets?

A 20A radial might be easier to wire unless you really want a 32A ring

Will all this be compliant with wiring regs such as socket spacing &
density?

Yes.

When Imperial College Dept of Computing had a student computer lab rebuild a
few years back, the desks had laptop sockets run in a local ring (well,
might have been a radial) one per row. Each desk had a local RCD for safety
+ convenience (no remote RCD) and each desk row plugged into the underfloor
power with a "commando" type plug. I *think* this was a 16A plug, so a 16A
radial circuit.

Similar principle. No, there is no real limit to socket density as long as
the protection is appropriate.

Conversely in the main computer room next door, each rack plugged in to a
single 32A commando under the floor - again a dedicated radial circuit.

Regards,

Stephen.
--
Tim Watts Personal Blog: http://www.dionic.net/tim/

"She got her looks from her father. He's a plastic surgeon."