Some advice please, regarding wiring inside garden shed workshop?

[R.Voles]

Some professional advice greatly appreciated here for design and costing purposes - two simple questions.

Background: We've just replaced a 25 year old wooden shed - good service but sagging a little from age and too small for our needs - with a larger one from Beast Sheds Ltd. (Recommended!).

The old shed was wired properly with an armoured cable spur from the house; a separate feed through an RCD switch box at the main house circuit board running about 8 metres out in the garden to a small 2-way (5A for lights and 13A) switch/junction box with RCDs inside the shed. I intend having the old junction box refitted in the new shed - it has had little use and is in good condition.

I know regs have changed since 1992... so before I get a sparks in, my questions are:

1) Since the junction box is effectively just on a fused spur (albeit with RCD protection at both ends) and not a ring, my understanding is that I am allowed only one twin 3-pin 13A socket from the junction box (by the door). Is that correct - or can I have a second twin 3-pin 13A socket over the workbench as we had before?
I can make do with extension cables if only one twin 3-pin 13A socket is allowed.

2) In the old shed, all the wiring was simply surface mounted on the wooden studs using cable clips over 1.5mm twin core & earth to the strip lights and 2.5mm to the sockets. Is it still OK to have exposed wiring like this or does it now require to be in plastic trunking?
(If so are there any specs/regs for the trunking type?)

Thanks hugely for a quick reply here.
(Anyone here in the Dalston or Shoreditch area? )

Best,
Reg

 

[The Ghost]

I suppose it is true "A little knowledge is dangerous" Good case in point.

 

[dksanders]

As Davesparks said, also:

If a fire in the garage could conceivably spread to the house, then the consumer unit in the garage has to be latest amendment compliant, i.e. either made of non flammable material (metal) or in a non flammable cabinet.

I've seen some outhouse fires where even 8m was not enough to stop the flames let alone the heat, from damaging/catching the house.

Unprotected cables should never be run at floor level, or even considered to be so.

In a garage/workshop environment I fit metal accessories with 20mm plastic conduit taking the T&E up to the rafters where they are then clipped. The accessories and wiring have to be suitable for the environment and my view is that where you have workbenches, and tools, ladders, lawnmowers etc hanging from wall, the chances are high that something will smash into a socket or cable damaging them.

Most electricians will get varying discounts for materials from their suppliers, which they may or may not (I do) pass partially or fully onto the client (to be competitive). So I would suggest your pricing the job is a pointless exercise.

What you first described as an RCD at the house end you later described as a 'circuit breaker on the switch rather than a fuse'. I'm a little concerned you may be referring to MCBs as RCDs, or vice-versa are you sure you know the difference.

If I arrived at a job and the customer told me what I had to buy, where I had to run cables, and how I had to do the job, I'd say thanks but no thanks and leave.

If your going to ask an expert to provide you with a quote, using his knowledge (and with all due respect, you don't have the appropriate knowledge) and his experience, then I can't see any point in you going to the trouble and time to find all this out repeating what he's going to be doing.

Unless of course you really intend to do it yourself, as you have stated a few times that you seem to think your 25 year out of date, inappropriate knowledge, qualifies you to specify what and how an up to date qualified electrician should do things.

 

[davesparks]

If a fire in the garage could conceivably spread to the house, then the consumer unit in the garage has to be latest amendment compliant, i.e. either made of non flammable material (metal) or in a non flammable cabinet.

.

There is nothing in the regulations about the conceivability of the spread of a fire, nor do they stipulate non-flammable, they stipulate non-combustible. The requirement is plain and simple that a new CU installed today on domestic premises should be non - combustible or enclosed in a non-combustible enclosure, premises means everything within the boundary of the property, it does not matter how far away from the house an outbuilding is, the requirement is the same.

An existing consumer unit does not have to be replaced purely on the grounds of being non-combustible to make an alteration to an existing circuit.

 

[The Ghost]

Yes indeed fire is a consideration along with earthing requirements in such a situation none of which have mentioned until now. If the OP has little to no knowledge of these things his knowledge could do him a dis-service.

 

[sparksburnout]

As Davesparks said, also:

If a fire in the garage could conceivably spread to the house, then the consumer unit in the garage has to be latest amendment compliant, i.e. either made of non flammable material (metal) or in a non flammable cabinet.

I've seen some outhouse fires where even 8m was not enough to stop the flames let alone the heat, from damaging/catching the house.

Unprotected cables should never be run at floor level, or even considered to be so.

In a garage/workshop environment I fit metal accessories with 20mm plastic conduit taking the T&E up to the rafters where they are then clipped. The accessories and wiring have to be suitable for the environment and my view is that where you have workbenches, and tools, ladders, lawnmowers etc hanging from wall, the chances are high that something will smash into a socket or cable damaging them.

Most electricians will get varying discounts for materials from their suppliers, which they may or may not (I do) pass partially or fully onto the client (to be competitive). So I would suggest your pricing the job is a pointless exercise.

What you first described as an RCD at the house end you later described as a 'circuit breaker on the switch rather than a fuse'. I'm a little concerned you may be referring to MCBs as RCDs, or vice-versa are you sure you know the difference.

If I arrived at a job and the customer told me what I had to buy, where I had to run cables, and how I had to do the job, I'd say thanks but no thanks and leave.

If your going to ask an expert to provide you with a quote, using his knowledge (and with all due respect, you don't have the appropriate knowledge) and his experience, then I can't see any point in you going to the trouble and time to find all this out repeating what he's going to be doing.

Unless of course you really intend to do it yourself, as you have stated a few times that you seem to think your 25 year out of date, inappropriate knowledge, qualifies you to specify what and how an up to date qualified electrician should do things.

Well said dude, you have put into words what everyone else is thinking. The guy has gone into the sunset now, having raped and pillaged the forum for knowledge, to undertake the work on his Jack Jones. Fairly obvious really though, he even left us with a parting titter!

 

[dksanders]

There is nothing in the regulations about the conceivability of the spread of a fire, nor do they stipulate non-flammable, they stipulate non-combustible. The requirement is plain and simple that a new CU installed today on domestic premises should be non - combustible or enclosed in a non-combustible enclosure, premises means everything within the boundary of the property, it does not matter how far away from the house an outbuilding is, the requirement is the same.

Hi Dave, Non-flammable/non-comubstable, I didn't bother to check the exact wording but aren't they the same thing?

I quote here from the IET:
421.1.201 Within domestic (household) premises, consumer units and similar switchgear assemblies shall comply with BS EN 61439-3 and shall:

(i) have their enclosure manufactured from non-combustible material, or

(ii) be enclosed in a cabinet or enclosure constructed of non-combustible material and complying with Regulation 132.12.

Consumer units in outbuildings or on the outside of a building
Regulation 421.1.201 uses the term ‘premises’. The question could therefore arise: do the requirements of the regulation apply to a consumer unit or similar switchgear assembly within an outbuilding such as a garages or shed, or mounted on the outside or a building?

Some dictionary definitions of ‘premises’ are ‘a house or building, together with its land and outbuildings’ and ‘the land and buildings owned by someone’.

However, Regulation 421.1.201 was principally introduced to cover the interior of a household building and any garage or other outbuildings integral, attached, or in close proximity to that building.

Doubt could exist about whether or not a particular outbuilding could reasonably be considered to be in ‘close proximity’ to the household building. A way of resolving this might be to make a judgement of the likelihood that fire originating inside the enclosure of a consumer unit or similar switchgear in the outbuilding might lead to the outbreak of fire in the household building or in any outbuilding integral or attached to it. Relevant factors to consider about such an outbuilding might include whether or not that building or its expected contents are highly combustible.

Regulation 421.1.201 is not intended to apply to a consumer unit or similar switchgear assembly that is not within a building, such as a consumer unit mounted outdoors on the outside of a building.

Personally I just fit metal CUs every time now but as the OP was stressing 'letter of the law' etc I included that for the avoidance of doubt.

Thanks for the reply.

 

[R.Voles]

What a thoroughly suspicious, critical and disagreeable bunch some of you are - many thanks again to those of you who offered sincere advice and help; SpinLondon, Telextrix. I'd considered posting for work in here, but now an electrician colleague of my plumber (family friend for 3 generations) will be popping in here for a site visit later in the week and I'm perfectly happy to pay him for a job well done.

You might like to consider that people seeking advice in this forum are potential customers and treat them with the respect and friendly approach they deserve.

Reg.