Regulations regarding a buried spur to power garage?

[d000hg]

As recommended in this thread, I am interested in what the rules are regarding a buried cable.

My garage is about 15m from my house, in between is my back garden and then an 8m wide tarmac drive/private road... it's access just to the garages of my house and our immediate neighbours. I have already received permission from the property management company (it's a new-build estate) to lay a cable as long as it is done properly and the surface made good afterwards.

My plan is to take the garage power as a spur from a socket in my living room (the closest room to the garage). I do not wish to set up a new circuit if possible or touch my main fuse box. The usage will be pretty light - a couple of sockets and lighting. I would like a chest freezer and ability to plug in hand tools but certainly not a workshop requiring serious power... 13A is just fine.

Can anyone tell me what the relevant regulations are here? I believe it can be done as a spur by anyone, with a standard RCD in the garage, but there are rules on the type of cable used, the way it is marked, and the depth it is buried - correct?

The plan so far is to bury an armoured cable, which I think meets regulations, but looking around the web I see people talk about conduit colours and so on. It seemed like they were using standard cables inside a conduit - what are my options here and what is recommended? I can see how putting everything inside a conduit/pipe is beneficial for replacing cables later!

I saw some people recommending you could "hammer a scaffolding pole through" underground, wash it out and use this as a conduit. Is that legal?!


ps: don't worry I am not the one doing the work but the person who is is a builder rather than electrician and hasn't done this exact job before, so I want to make sure I know what he's doing is correct.

 

[PrenticeBoyofDerry]

If you are not doing the job, why is a builder? Employ someone who is experienced and qualified to do so, then you can have the job done right and directly terminated at the consumer unit and provision made for any considered updated demand in the future.
You will require to factor in the demand required, the method of installation and voltage drop before you can choose a cable size, the cable would be buried about two foot deep within a duct, include drawstrings for pulling cable and any replacement cable, SWA is a must, you will also require to take into consideration of whether equipotential bonding is required within the garage.

A spur from an existing socket in the house could cause power loss via nuisance or fault trips associated with the distribution to the garage as well as circuit cables and electrically loaded equipment within in the garage. This could result in that socket circuit and any circuit protected by the same RCCB/RCD taking a number of circuits out. So I would recommend trying to avoid that.

The builder will require to document inspection schedules, test result schedule and complete a electrical installation certificate, is that within their scope?

 

[bernardgreen]

The builder could install the duct and then the electrician can pull in the correct size of SWA. Internal diameter of 30mm or more.

As said at least two foot deep with a cable marker tape one foot above the duct. Take photos to prove it is that deep in case some one ( builder, building inspector, electrician ) requires proof before signing of the installation. Put in two ducts, one for power and the other for ELV cables ( data, phones, intercom, alarm etc etc ).

If possible bring the end of the duct up inside the garage.

No sharp bends, a single un-jointed run is best. Keep the ends covered to prevent stones getting into the duct. ( they damage cable as it is drawn in ).

Get details from the site managment about existing cables and pipe runs before digging. Trenching machines cut water pipes like a hot knife through butter,

 

[d000hg]

Is 2 feet deep a regulation? It seems very deep!

Is a non-certified person allowed to do this work if we do not come off the main breaker e.g. can it be done as DIY or by a general tradesman? I know touching the circuit breaker requires an electrician but my understanding is a spur can be done by anyone... or does the fact it is buried change that fact?

By the way, dies the duct/conduit have to be anything special or if armoured cable is used, would any pipe be acceptable?
Is a conduit a requirement, or just common sense so you can replace/remove cables later if/when needed?

Please quote/link exact rules you are referring to please - searching online you see all kinds of nonsense posted about what you "must" do and I would like to be able to know the rules in case I get called on them.
[/i]

 

[nickjb]

I don't think there is an official figure, the regs just say something like "sufficient depth so that it is unlikely to be damaged". 600mm seems to be universally agreed to satisfy this condition unless there are special circumstances. You might get away with a bit less if you can justify it.

I think all exterior work used to need sign off but this has changed with the latest revision, hopefully someone can confirm/deny. That said if you do it as a new circuit, which you really should, then it is still notifiable.

No requirement for conduit. You can bury the cable directly. The reason conduit was suggested is that you/your builder can do the donkey work then the electrician just pulls the cable through and connects it up.

 

[d000hg]

Seems like there's no reason not to use a conduit, if you can use a plastic water pipe or similar, in that case. Why wouldn't you want to be able to pull the cable if you ever needed to!

I still don't really get the separate circuit argument though - this seems more like adding a conservatory and chucking in a couple of sockets and lighting to me. Is it just a case of "this is the proper way"? My main motivation not to do this is just cost, but being able to get a spark out just to connect it up seems reasonable. Do they have to lay the cable or could we do everything else, leaving the cable end for him to wire up?

 

[PrenticeBoyofDerry]

Is 2 feet deep a regulation? Can you provide a link because that seems very deep - even the microtrenchers I see online (used on pavements etc) don't seem to be able to get that deep!

Is no specified distance given within the regulations but guidance and rule of thumb would suggest at least 600mm deep.

Is a non-certified electrician allowed to do this work if we do not come off the main breaker?

Depend s what you mean by non certified and electrician? At the end of the day the work needs to be designed, installed and a certificate issued to prove it is safe, by someone who understands design, installation, regulations and can correctly fill in the required certificate and understand what they are documenting is compliant and safe.

A new circuit seems like overkill and would mean ripping up interior decoration; I know touching the circuit breaker requires an electrician

I would have thought that altering anything electrical would require an electrician, builder are generally not electricians and don't have the knowledge or competency levels

but my understanding is a spur can be done by anyone... or does the fact it is buried change that fact?

I wouldn't trust anyone to alter your electrics, they are people out there that are specialised in this field, who can do this type of work in a competent safe method.

Can anyone quote exact rules they are referring to please?

There are no exact rules, but you require to prove what has been done is compliant to the relevant regulations and that the installation has been designed and installed in a way that will not cause harm in construction or use.
The best person for this is a qualified experienced electrician not a bloody builder, who as you have said does not know what they are doing!!

 

[d000hg]

PBoD there are definitely things you can do legally as DIY in terms of electrical work, and no reason not to. The idea you need an electrician to do anything is not really true - even I can wire a lighting circuit or add a socket after reading up. There are definitely specific things you can and cannot legally do without qualifications, and things that do and do not need signing off.

So I want to know which things are in which category here - I know that touching the main breaker cannot be done except by an electrician but I know anyone can take a regular spur off a mains socket. However as for burying a cable, does it make a difference?

 

[Murdochcat]

As recommended in this thread, I am interested in what the rules are regarding a buried cable.

My garage is about 15m from my house, in between is my back garden and then an 8m wide tarmac drive/private road... it's access just to the garages of my house and our immediate neighbours. I have already received permission from the property management company (it's a new-build estate) to lay a cable as long as it is done properly and the surface made good afterwards.

My plan is to take the garage power as a spur from a socket in my living room (the closest room to the garage). I do not wish to set up a new circuit if possible or touch my main fuse box. The usage will be pretty light - a couple of sockets and lighting. I would like a chest freezer and ability to plug in hand tools but certainly not a workshop requiring serious power... 13A is just fine.

Can anyone tell me what the relevant regulations are here? I believe it can be done as a spur by anyone, with a standard RCD in the garage, but there are rules on the type of cable used, the way it is marked, and the depth it is buried - correct?

The plan so far is to bury an armoured cable, which I think meets regulations, but looking around the web I see people talk about conduit colours and so on. It seemed like they were using standard cables inside a conduit - what are my options here and what is recommended? I can see how putting everything inside a conduit/pipe is beneficial for replacing cables later!

I saw some people recommending you could "hammer a scaffolding pole through" underground, wash it out and use this as a conduit. Is that legal?!


ps: don't worry I am not the one doing the work but the person who is is a builder rather than electrician and hasn't done this exact job before, so I want to make sure I know what he's doing is correct.

I'd venture to suggest that allowing a builder to undertake this work may not be the best way forward.

Re the cable passing under a road - you may need to go deeper than 600mm and/or provide additional protection as this is passing under a track. I'd be asking the site contractor for the ACTUAL requirements they want!

re connecting to the house - what is the earthing? is there RCD protection in place?

Re the builder doing the work - would you ask a plumber to fix your roof?

 

[PrenticeBoyofDerry]

PBoD there are definitely things you can do legally as DIY in terms of electrical work, and no reason not to. The idea you need an electrician to do anything is not really true -

If that is the case why are you asking electrical question on a forum dedicate to electrics if the do not require an electrician?

even I can wire a lighting circuit or add a socket after reading up. There are definitely specific things you can and cannot legally do without qualifications, and things that do and do not need signing off.

I never said you couldn't put you still need to comply to the relevant regulations in doing so and prove what has been done is safe, not everyone has the knowledge or the equipment to do this

So I want to know which things are in which category here - I know that touching the main breaker cannot be done except by an electrician

What is a main breaker?

but I know anyone can take a regular spur off a mains socket.

They cannot legally without proving what has been done complies and is safe.

However as for burying a cable, does it make a difference?

Again complies and safe

 

[d000hg]

Re the builder doing the work - would you ask a plumber to fix your roof?

It's putting a cable in a hole in the ground, not wiring a house. I could do this myself on the electrical side as long as I knew what rules I had to stick to - digging the hole is the hard bit and I don't see many electricians wanting to dig a trench. They'd say "get a builder"!

If a slate fell off my roof, I would be happy getting a handyman rather than a roofer. If my roof needed replacing, I'd get a roofer.

Seems a bit pointless having an electrical forum if all you get told is "hire an electrician" From an electrical point of view this is about the simplest job one could ask for, it's simpler than adding a lighting circuit!

 

[Murdochcat]

Re the builder doing the work - would you ask a plumber to fix your roof?

It's putting a cable in a hole in the ground, not wiring a house. I could do this myself on the electrical side as long as I knew what rules I had to stick to - digging the hole is the hard bit and I don't see many electricians wanting to dig a trench. They'd say "get a builder"!


Seems a bit pointless having an electrical forum if all you get told is "hire an electrician" From an electrical point of view this is about the simplest job one could ask for, it's simpler than adding a lighting circuit!

If and I say IF you get the builder to dig the hole make sure that the sparky witnesses the depth and protection in the hole - I've seen builders saying the hole is xxxmm deep whereas in reality it was half xxxmm deep.

Sure we don't like digging hole but I NEVER allow anyone bury a cable I'm going to sign off.

Anyway - do you have guidance re the depth under the track/path - this sounds very fishy to me.

 

[d000hg]

There are no exact rules, but you require to prove what has been done is compliant to the relevant regulation

That's what I'm asking for. You can't say there are regulations but no exact rules - the regulations ARE the rules.


This is essentially a DIY project I am hiring someone to do the donkey work. This is a DIY forum. If I need to have an electrician do part of the job or sign it off, that's fine. But I need to know which parts... he isn't going to dig a trench but equally it's no good him turning up and telling us our trench is illegal and he won't do his bit of the job. I want to be clued up in advance.

 

[d000hg]

If and I say IF you get the builder to dig the hole make sure that the sparky witnesses the depth and protection in the hole - I've seen builders saying the hole is xxxmm deep whereas in reality it was half xxxmm deep.

Sure we don't like digging hole but I NEVER allow anyone bury a cable I'm going to sign off.

Anyway - do you have guidance re the depth under the track/path - this sounds very fishy to me.

Good advice.

I have a letter saying they are happy for it to be done, as long as it is done properly. No stipulations at all. But this is the next thing to a private driveway really.
Out of interest, if it was on my land only would all the same rules apply?

 

[PrenticeBoyofDerry]

You can choose to ignore me if you wish and be quite blinkered about it, and wait for someone to give you answer you want to hear, it may not particular be the correct or safe answer, but that is up to you.
I have offered you sound and safe advice, it is true you do not need to be qualified to take on electrical tasks, but by law you do require to make sure what you have done is safe. And safety is not proved by ticking an imaginary box when plugging in and the lights come!

I post this reply in your best interests and not for any other reason.
I have nothing against someone having a go at DIY if the task/project is within their scope, but you are employing someone to do the work for you, for goodness sake, employ someone who has a knowledge, skill and experience of what to do!