Network wiring in a small office

[buzzbomb]

I'm going to be moving into a rented office space soon, and would like to save some money by putting in the network (Cat5) cabling myself.

The space is open plan, with some heavy duty plastic trunking around the edge that carries the mains wiring. The are numerous 13amp sockets flush mounted on the ducting.

I'd like to run the network cables through the same trunking, and mount the network sockets on it as well.

I'd be grateful if anyone could tell me (or point me to somewhere I could find out)...

1/ Do I have to maintain any physical separation between the main wiring and the low voltage network wiring.

2/ Should I be using a particular type of cable (I've found low smoke, zero halogen Cat5 cabling on screw fix - its more than 3 times the price of basic Cat5 cabling).

3/ Is there anything else I should be concerned about. I've done bits and pieces of network wiring over the years with no problems. I'm just a little worried about contravening one or more of the many building regs we seem to have these days.

Thanks

B.

[shaun]

Sorry for stating the obvious but why not save even more money and go wireless?

[Chip]

On Wed, 26 Oct 2005 16:58:19 GMT,it is alleged that buzzbomb spake thusly in uk.d-i-y:

Not sure about the building regs and LSF Low halogen cable requirements, but usually that kind of 'skirting' or 'dado' trunking has a separate compartment for comms wiring, sometimes even 2 (top and bottom). If you remove one of the cover sections you should see if this is the case. It's definitely good practice to keep mains separated from comms wiring in trunking like that.

For what it's worth (not much as the info is 10yrs+ out of date, we used to install normal PVC wiring in that trunking and it complied in

1. YMMV these days though, especially with cat5's internal insulation sometimes being polyethylene [and thus flammable].

[buzzbomb]

Not an unreasonable question.... a couple of not unreasonable answers...

1/ You don't put servers on wireless, well you don't if you want decent performance. 2/ Not all our kit is capable of wireless. 3/ The network does include a wireless access point for a couple of laptops

B.

[Rob Morley]

You're not supposed to run data cables close/parallel to power cables. If the office has a suspended ceiling you could just run long patch cables over it (avoiding cables to lighting) and let them dangle.

[Owain]

Yes, it should be run in a separate compartment of the trunking. Might be easier to run a length of minitrunking adjacent to the mains trunking.

LSOH is usually for use in plenum voids, where the space eg above a suspended ceiling forms part of the air-conditioning ducting.

As a workplace, Electricity at Work Regulations will apply. (Part P won't though!) If you have a lot of IT equipment you may have high earth leakage currents and need to look at the circuit earthing arrangements, such as High Integrity Earthing.

Owain

[Lurch]

On or around Wed, 26 Oct 2005 16:58:19 GMT, buzzbomb mused:

I like going to sort jobs out where customers wanted to 'save some money'. The job usually looks like it's been installed by an idiot and invariably gets laughed at by me.

The bitter taste of poor quality lingers on long after the sweet taste of a cheap deal.

Picture?

Depends what it is exactly. A picture could help, or it may not. If you remove some of the lid the manufacturer and \ or part number could be stamped in the base. You'll want to get boxes to match the trunking as you don't just use normal boxes with dado trunking (assumin that's what it is).

Your new office.

Yes.

Depends.

Leave it to someone who knows about these things. ;)

[:::Jerry::::]

myself.

Security might be one very good reason, then there is cost, assuming that the OP already owns most of his own hardware (such as routers and switches etc.), cat5 cable is cheap providing it's bought from the right places.

[Lurch]

On or around Wed, 26 Oct 2005 20:22:59 +0100, Rob Morley mused:

Bugger, better go and rip out those thousands of miles of cat5's I've put in in segregated dado trunking in close proximity and parallel to power then. ;)

[shaun]

Good answers ;-)

[:::Jerry::::]

cables.

AIUI you shouldn't run data and power cables together, both for safe separation and possible cross-talk reasons, but you can run them within the same trunking if they are physically separated. See (mind any line wrapping);

[shaun]

Cable is indeed cheap.

Running and terminating it correctly (with patchbays and wall cabs etc) is not so cheap.

[dennis]

>

I think you will find the rules for crosstalk aren't for TP Ethernet but for things like rs232, etc. You don't get problems even if you run the cat5 ontop of the mains.

The separation for safety reasons is another matter. There is small chance that mains could get onto the cat5 and then into the equipment. To do this would require the insulation to fail on the mains cable and on the cat5e and a fault to occur in the isolation transformers in the NIC. A fairly unlikely chain of events.. I doubt if the extra separation provided by the trunking will actually make any difference in practice. However rules are rules and best not broken if you don't understand them.

[Will Dean]

Moderated by the fact that tight control of costs is one of the things that separates successful small businesses from failed ones. I don't suppose you laugh at the customers who go bust owing you money...

I'm surprised no-one's advocated 'stand the hub/switch on top of the server and run the whole lot in pre-wired patch cable thrown on the floor behind the desks', which is a pretty common solution, very cheap and less of a cause of problems than crap fixed installations, IME.

Will

[Lurch]

On or around Wed, 26 Oct 2005 23:42:44 +0100, "Will Dean" mused:

I'm going to have to come back to that one, it doesn't seem to make sense to me.

Thanks for your concern anyway.

[dennis]

I did the whole of a stand at CeBit like that when I got there with the kit and discovered none of the stuff installed actually worked. (I liked the German electricians attitude to mains extensions. "If you can hold the lead it isn't overloaded".) ;-)

Trunking stuck to the wall with doublesided tape springs to mind.

[Christian McArdle]

Basically yes.

LV mains cabling (i.e. standard 230V stuff) must be separated from extra low voltage comms cabling by either:

(a) 5cm (b) Physical barrier (c) Comms cable with mains quality insulation/sheathing

(b) is the usual method, especially if your trunking has a separate compartment for it.

(c) is normally impossible to find for data cabling, although you can use multicore mains cable for some applications, such as intruder alarms, to avoid the need to separate physically.

Christian.

[Rob Morley]

Better had then :-)