extension sockets instead of proper sockets on a ring main

[ashirusnw]

We want to provide mains power to some desks in the middle of a open plan area, which has a concrete floor with laminate flooring - so no where to run cabling under the floor.

The desks will have between 2 to 8 computers (and their screens). The problem is how to get the ring mains to this area.

It's got a suspended ceiling, so one option is to run all the cabling we want down a "pipe" (or fake pillar) to the desks but this will never look pretty.

So the other option is to run cabling from one of the walls, over the floor surface but covered by conduit to the desks in the open area. (The nearest wall is only 2m away.) The conduit looks like this:

But in order for the conduit to be low profile, unobtrusive and not a major trip hazard, we have to minimize the cabling so I imagine that running the wiring for (say) 8 double sockets on a "proper" ring requires at least two cables/wires to the main area, which means a fatter floor conduit.

Can I instead have a single cord (i.e. not a ring/radial circuit) running along the floor to just one double socket, and from there just attach one or two regular 8 gang extension sockets to get the amount of mains sockets dependant on the number of computers.

I've always been told that extension cables are a bad idea and should be avoided but here it means that we have minimal cabling along the floor (I have to allow for two cat 5e network cables within the conduit too). It also means we can use these fancy surge protecting extensions that have a battery to act a UPS in the event of a power failure.

If we run this single cord and its double socket off it's own circuit breaker/MCB, can we happily use this setup with extension sockets from a overload and electrical safety point of view?

thanks,
Ash

P.S. I know I've been a frequent poster in the past few weeks and I hope I'm not taking advantage. If it's any consolation, I really appreciate the excellent advice so far and I'm learning a lot!

 

[ban-all-sheds]

We want to provide mains power to some desks in the middle of a open plan area, which has a concrete floor with laminate flooring - so no where to run cabling under the floor.

The desks will have between 2 to 8 computers (and their screens). The problem is how to get the ring mains to this area.

I am really struggling to see how this is not a place of work, and therefore how it is not a location where things like the Electricity at Work Regulations, the Health and Safety at Work etc. Act, employer liability etc apply, and therefore how it is not a location where they only thing you should do is to get a competent electrician involved.

It's got a suspended ceiling, so one option is to run all the cabling we want down a "pipe" (or fake pillar) to the desks but this will never look pretty.

It will look prettier than dangers, incidents, prosecutions....

not a ring/radial circuit

What, neither?

I have to allow for two cat 5e network cables within the conduit too

No you don't.

I really appreciate the excellent advice so far and I'm learning a lot!

Well I hope you appreciate this advice - please get an electrician, because you have not learned enough not to be putting people's lives at risk.

 

[ashirusnw]

We want to provide mains power to some desks in the middle of a open plan area, which has a concrete floor with laminate flooring - so no where to run cabling under the floor.

The desks will have between 2 to 8 computers (and their screens). The problem is how to get the ring mains to this area.

I am really struggling to see how this is not a place of work, and therefore how it is not a location where things like the Electricity at Work Regulations, the Health and Safety at Work etc. Act, employer liability etc apply, and therefore how it is not a location where they only thing you should do is to get a competent electrician involved.

He's competant, I'm sure and all our work as to be signed off by Building Control, with electrical safety cert etc.

It's got a suspended ceiling, so one option is to run all the cabling we want down a "pipe" (or fake pillar) to the desks but this will never look pretty.

It will look prettier than dangers, incidents, prosecutions....

So are conduits on the floor never used in workplaces that abide by H&S etc???

not a ring/radial circuit

What, neither?

No neither. You don't *have* to have a ring circuit - which in this case would necessitate an extra cable for the return to the CU - many places in the world apparently often don't use proper ring circuits. It wouldn't be radial either as there is only socket in this scenario - so one single cable from CU to the double socket in middle of working area. (Over which there will be a desk - it's not gonna lie about in the open.)

I have to allow for two cat 5e network cables within the conduit too

No you don't.

Do you mean because network cabling shouldn't be run alongside power because of interference? What choice do I have here? Either dropped from the ceiling or run along the floor, we need to get both power and connectivity to the open area!

The people in the open area work with people in two offices in the workspace so there will be a small network switch in the open area to connect those two offices and the computers in the open area. We need speeds better than wifi (gigabit).

I really appreciate the excellent advice so far and I'm learning a lot!

Well I hope you appreciate this advice - please get an electrician, because you have not learned enough not to be putting people's lives at risk.

So laying a floor conduit is putting people's lives at risk?

Or are you referring to the earlier question where we were discussing earthing requirements for computers? Even in that case, we appropriate training the H&S aspect can be mitigated.

Really it's not a question of a competent electrician (the work has to be signed off). There are many electricians who treat the regs as the bible and over specify instead of being flexible even within the remit of regs and H&S. It's impossible to know if an electrician is being over cautious without getting a second or third opinion. Of course there are those jobsworths who think that not obeying every letter is going to result in fried workers, and there are those that are more pragmatic and realise what's actually necessary.

 

[ericmark]

I would be considering power trunking of some type. I have used it many times where I want to drop power from an overhead supply and although expensive to buy the fitting time is reduced so evens out.

Also used the same for lighting where machinery can obscure it so needs rearranging from time to time.

I had many an argument with my foreman over ceiling drops he wanted to use conduit I wanted to use SWA the point was over the number of fixings required.

I have with long drops put it inside Unistrut and used captive nuts and bolts to secure. With of course a bit of something to stop it damaging cable.

There are chasing tools which will cut channels in concrete floors but much depends on building design as to if you can cut into floor. I have waited ages for permission to cut into floors and drill holes through walls.

This it would seem is not a DIY job and as such one has to be very careful as to what one does. I have in the past been stopped from doing work purely because the insurance would not cover.
There seems to be a growing problem where on one hand firms are looking for multi tasking but insurance firms are looking at what training is given.

 

[ashirusnw]

I would be considering power trunking

To the layman like me, is this just "trunking"? Do you mean dropping from the ceiling or on a floor conduit. The open area is 2m away from any wall.

I wanted to use SWA the point was over the number of fixings required.

SWA is Steel Wire Armoured cable, right? Would you recommend using amoured cable if it's being run along the floor?

There are chasing tools which will cut channels in concrete floors but much depends on building design as to if you can cut into floor. I have waited ages for permission to cut into floors and drill holes through walls.

Yup, that's the third option but same problem. It took us 3 months for permission for the work we are doing, they will take years to agree to chase concrete.

 

[Chri5]

Get a chippie in and cut a 100mm channel in the laminate between wall and centre of the island. Run cables, cat5 requires 50mm air gap away from power cables.

Cover channel with 150mm top, made from wood with bevelled edge (to reduce trip hazard). Or steel plate (which will need earthing via a stud).

To reduce the cat5 and a avoid a cable for each network device, you might want to run only 2 cat5 cables (one as a spare) and position a hub at the island to feed the island network items.

Another choice would be cabling via the floor below and hole between floors. If the floor below is owned by your client and has false ceiling that could be the easiest way.

Or a power pole, which has already been mentioned.

 

[viewer]

Being pragmatic;
the overhead idea (especially as you have a suspended ceiling) seems the better option for no other reason than that the capped floor system will become a problem in time. Cleaning the join between floor and cap becomes impossible and it looks awful. They get kicked or furniture is rammed into them (office chairs seem designed to catch their wheels on them) and so eventually there are bits of tape etc. Neither safe nor aesthetically pleasant. You also don't have worries about data and power cables running in parallel
The idea of a single double socket at low level is probably also something to reconsider - how long before the plug is pulled just at a time to destroy the maximum amount of work? Using a dedicated circuit to overhead with a socket above the desk allows movement of desks, machines etc for use and cleaning without that risk.

 

[ban-all-sheds]

He's competant, I'm sure and all our work as to be signed off by Building Control, with electrical safety cert etc.

If you are using an electrician then you are not to get involved in ANY of the design decisions you are asking about here.

You can spec the choice between power poles and floor cable covers, but none of the stuff to do with circuit topologies, running cables of two different bands, MCB ratings etc etc are anything to do with you, so leave it alone.

So are conduits on the floor never used in workplaces that abide by H&S etc???

They are, but they can still be a trip hazard. The point I was making is that you must not subordinate safety to aesthetics.

No neither. You don't *have* to have a ring circuit - which in this case would necessitate an extra cable for the return to the CU - many places in the world apparently often don't use proper ring circuits. It wouldn't be radial either as there is only socket in this scenario - so one single cable from CU to the double socket in middle of working area

So - if the circuit is neither a ring nor a radial, would you care to tell us what it is?

Do you mean because network cabling shouldn't be run alongside power because of interference?

No, I mean because you may not run LV and Cat5e cables in the same containment system.

What choice do I have here?

Only one:

Let your electrician do the job.

So laying a floor conduit is putting people's lives at risk?

No, but some of the things you said you were going to do (your original post made no mention of an electrician being involved) would.

It's impossible to know if an electrician is being over cautious without getting a second or third opinion.

Expect to have to get a 2nd and 3rd electrician when the 1st and 2nd walk away after you start telling them how to do their job because of opinions you have gleaned from strangers on internet fora.

 

[sparkiemike]

The OP has already been advised in other posts to get a competant electrician!. In a previous post he admitted the electrician does not speak english.

I don't think we have been told everything. I suspect he is doing the work himself?

 

[ban-all-sheds]

The OP has already been advised in other posts to get a competant electrician!.

I know.

In a previous post he admitted the electrician does not speak english.

So how likely is he to be able to read English, and thus understand, and ensure he complies with, all of the health and safety legislation which applies to this work?

ashirusnw - it is possible to find electricians who do speak English - why are you risking using one who does not?

I don't think we have been told everything. I suspect he is doing the work himself?

Possibly.