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WaynW

Powering A Garage

Question

Hello and thanks for reading,

 

I have a Detached Garage being built at the end of the property approx 12 meters from the rear of the house, and 19 meters from the consumer unit which is in the front hallway, there is a side alley so cables can run straight down. I want to send power to the garage for, lighting, outlets and a gate and garage door opener.

 

I am aware that my consumer unit has no free space, What is the best and most cost-effective set up's to achieve this?. Also I went to the local authority to check on building plans, who stated that as long as it was armoured cable I can put it under the garden pathway... however I was under the impression it needed to be buried pretty deep? but he said that's only with general soil areas to stop from accidents. Under a concrete path is fine. Which would be useful considering other utilities, soak away, massive tree.

 

Can anyone please tell me what is going to be needed for this set up. Thickness and standard of cable for the main run, capacity consumer unit to get for the garage, new consumer unit at the house?, I do basic electrics but never this level. I want to do what I can to save money put will get the proper Part P for the connecting, ect.

 

 

Thanks again,

 

Wayne

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25 answers to this question

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You're best finding a local electrician and then just doing the labouring for them, i.e. get the cable run to their specification, and then they can connect up and sign it off. I would be wary of turning up at a job after it was half done following advice from the internet, no matter how sound the advice might be.

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and for the record I suspect the majority of sparks won't turn up and test / certify / Part P this if you DIY..

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3 hours ago, WaynW said:

Hello and thanks for reading,

 

I have a Detached Garage being built at the end of the property approx 12 meters from the rear of the house, and 19 meters from the consumer unit which is in the front hallway, there is a side alley so cables can run straight down. I want to send power to the garage for, lighting, outlets and a gate and garage door opener.

 

I am aware that my consumer unit has no free space, What is the best and most cost-effective set up's to achieve this?. Also I went to the local authority to check on building plans, who stated that as long as it was armoured cable I can put it under the garden pathway... however I was under the impression it needed to be buried pretty deep? but he said that's only with general soil areas to stop from accidents. Under a concrete path is fine. Which would be useful considering other utilities, soak away, massive tree.

 

Can anyone please tell me what is going to be needed for this set up. Thickness and standard of cable for the main run, capacity consumer unit to get for the garage, new consumer unit at the house?, I do basic electrics but never this level. I want to do what I can to save money put will get the proper Part P for the connecting, ect.

 

 

Thanks again,

 

Wayne

 

 

Welcome to the forum, from the information in your post you have got a few problems to resolve if you want all this work installed, tested and certified correctly. First of all there is insufficient information for anyone to do any accurate cable calculations. The next issue is legal liabilities for the safety of the design, construction & testing of the new circuit. DIY electrical work is permitted in the UK but realistically adding new circuits and or fuse boxes is beyond the scope of DIY'ers due to their lack of appropriate calibrated test equipment or knowledge of relevant regulations. An understanding of wiring regulations (BS7671) is needed, but this is a document that you cannot freely download (possibly loan a copy from your local library or purchase a copy yourself for around £75 - £80, https://www.amazon.co.uk/d/cka/Requirements-Electrical-Installations-Iet-Wiring-Regulations-7671/1849197695/ref=sr_1_1?ie=UTF8&qid=1492194878&sr=8-1&keywords=bs7671+17th+edition+amendment+3). An understanding of applicable building regulations is also needed. Building regulation approved documents can be freely downloaded, https://www.gov.uk/government/collections/approved-documents Where Part-P 'electrical safety' will have specific relevance to your project.

 

Once the work is complete you should have an Electrical Installation Certificate and a Building regulations compliance certificate issued, these will reference the contractor who has designed, installed and tested the work, (including the serial number(s) of their test meters). However very few reputable electrical contractors are willing to take on the liability of signing these documents, unless they have been involved in the project from day 1. As Lurch suggests if you want to do some of the work yourself, it is best to get a local electrician round to come and discuss the work, do the design with you, agree what elements they are happy with you doing (including any visits to check installation aspects before cables are hidden / buried etc.). Some aspects of the existing installation must also be checked before doing any alterations temporary or permanent. These included equipotential earthing and bonding. It is not just a case of what cable do I need from a to b. 

 

You could do it all DIY, but to get it fully certified without involving an electrician who can notify the work for you, you need prior agreement with your local Authority Building Control (LABC), and they will undertake the inspection and testing aspects for a fee that should be listed on your LABC's website.  If you try to do it all, then only get an electrician involved at the end, it could cost a lot more as they will probably want to dismantle a lot of what has been connected in order to fully test the new circuits(s). That is of course assuming you can find someone who  is willing to come along and test and sign and take liability for someone else's work they have no prior knowledge of.

 

Doc H.       

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Hey great info thanks,

 

Sorry for the misunderstanding. I am not going to do the electric side, I would feel more comfortable with it done properly, Part P. Happy to do basics which I have. But I shall take the hit in pride and say this is beyond me lol. The parts I was going to do myself was trenching out for the cable line, buying materials, fitting up the garage and gate door openers and basically being a laborer. Any installations of consumer box, laying lines and new circuits I will leave to the electrician. As I agree that they would be wary to come in and sign off on your work. I know I would.

 

I just wanted to find out about what kind of set up would this require. Any information which you advise and have given, thanks!. What ball park cost would this kind of work be. Ect.

 

Regards

 

Wayne

 

 

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1 hour ago, WaynW said:

The parts I was going to do myself was trenching out for the cable line, buying materials, fitting up the garage and gate door openers and basically being a laborer.

 

Laying the cable/trenching and fitting the gate openers etc would be fine, but again speak to whoever is going to be doing the work first. Same for buying the parts, you don't know what parts you require and neither do we, and different electricians will have different equipment they would prefer to fit, and most would probably prefer to supply it as well. I know I wouldn't bother with a lot of jobs if the customer said they were supplying materials.

 

1 hour ago, WaynW said:

I just wanted to find out about what kind of set up would this require. Any information which you advise and have given, thanks!. What ball park cost would this kind of work be. Ect.

 

With the info we have so far there isn't really enough information to provide any costings or equipment lists. Again, there will probably be several different ways of doing the job so you would need to speak to the electrician doing the work to find out what materials you need.

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Hi Wayne,

 

The problem you have, is that there are a few different ways of approaching this job, and just because one of us thinks one way is right, does not mean someone else will agree!!

 

Still, the first thing that needs considering is your consumer unit. It would be simple enough to add another small one next to it, just to feed the garage, BUT, if your existing one has no spare ways and is ancient, it might be as well to change it now, and kill two birds with one stone as it were, because what if you wanted to add more circuits in the house in future??

 

Then again, depending on the age of your house and what consumer unti you have now, changing the thing might be a bag of laughs, and it might be a lot of expense for little gain...

 

Next, do you know what earthing type you have in the house, as this will have a bearing on what accessories you need, and the choice of cable to the garage.

 

What are you planning to install in the garage??

 

When it comes to the depth of the cable, there is no law that says how deep it has to be buried.

 

What is required, is that,

 

1, above the cable there is a marker tape laid about a foot above it, so that if someone does dig a hole they are alerted to the presence of the cable,

 

and

 

2, that it is deep enough so that it is not "reasonably forseeable" that it might be damaged. What this means in practice, is that the cable is buried about 450mm down, but in areas where people might dig holes, like in gardens or flower beds, that it is about 600mm down.

 

You can buy flexible twin wall cable duct. You could install this and fill all the trench in, and then an electrician can just pull the cable through at a later date. This is what i would do...

 

I would not go and buy any materials myself, as we all have our own preference as to what to use!! Remember now, if the electrician is a happy bunny on the job it will be cheaper!!

 

I would get the cable duct, stick it in a trench at the right depth, not forgetting that any bends want to be nice large radius ones, and leave it at that, the electrician can then screw some boxes to the wall, pull the cable though the duct in a few minutes, and connect it all up..

 

You COULD do it all yourself, but you will have no means of testing it to make sure it is safe, as you will not have the right test equipment, and you will have to pay the building regs people to test it for you.. Be cheaper just to get an electrician to be honest.

 

Nothing to stop you building the garage and telling the building regs people that you have decided against having any electrics, building it, getting it signed off, and doing the electrics later!! A bit naughty, but who cares..

 

Anyway, here is a link to the sort of cable duct you need.. [just think, if it ever goes wrong, you can just pull a new cable through!![

 

Nearly forgot.. The cable duct has string threaded through it.. DO NOT lose the ends, as the string is used to pull a bit of rope through that is then used to pull the cable through!! DO NOT LOSE THE ENDS OF THE STRING!!!

 

http://www.draindepot.co.uk/63mm-x-50m-black-twinwall-electric-cable-duct.html

 

This duct is 50mm diameter inside. This might seem a bit big, but then it means that you will be able to get any size cable you might want to use through it very easily [for all i know you might want air compressors and 300A welders in the garage] Obviously, if you are just going to run a few lights you could get a smaller duct..

 

john..

 

 

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Good helpful post John for the OP.

Just a slight comment to Johns post, when he says put a string in the duct, make it more like a bit of 6 or 8mm blue rope, you can get it at builders merchants or Screwfix etc. and when you pull the cable in pull in a new draw rope with it, you just never know when it might come in handy.

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or if you loose the rope, a bag tied to the rope and a vacuum on the other end will usually pull a rope through. may cost 5p though...

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1 hour ago, roys said:

Good helpful post John for the OP.

Just a slight comment to Johns post, when he says put a string in the duct, make it more like a bit of 6 or 8mm blue rope, you can get it at builders merchants or Screwfix etc. and when you pull the cable in pull in a new draw rope with it, you just never know when it might come in handy.

 

Was once left a duct by groundworkers to pull a fire alarm link through. The drawire was mostly that nylon gardeners string (that has an annoying bit of stretch to it), but it obviously wasn't quite long enough, the last few metres were cat5 data cable tied on with a big ugly knot. Its like it must have been "****, I've forgotten the rope, quick lads, look in the skip see what you can find!"

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1 hour ago, roys said:

Good helpful post John for the OP.

Just a slight comment to Johns post, when he says put a string in the duct, make it more like a bit of 6 or 8mm blue rope, you can get it at builders merchants or Screwfix etc. and when you pull the cable in pull in a new draw rope with it, you just never know when it might come in handy.

 

Hi Roys,

When you buy the duct, it already has like nylon string in it. [thank god!] but it is very thin, but well strong though!!

 

But like i said..

 

4 hours ago, apprentice87 said:

Nearly forgot.. The cable duct has string threaded through it.. DO NOT lose the ends, as the string is used to pull a bit of rope through that is then used to pull the cable through!! DO NOT LOSE THE ENDS OF THE STRING!!!

 

Like you said though, 6mm or 8mm rope is the stuff to pull through, then use this to pull the cable through. Like you also said, pull in a new rope with the cable and leave the rope in the duct, might be useful some day!!

 

Could you at a later date pull a phone line or something through?? I have an idea that you are not supposed to mix voltages though?? You know, not have a 230V cable with insulation rated for this, and then a phone cable with insulation rated for, well, being a phone cable!!!

 

john..

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16 minutes ago, apprentice87 said:

 

...

Could you at a later date pull a phone line or something through?? I have an idea that you are not supposed to mix voltages though?? You know, not have a 230V cable with insulation rated for this, and then a phone cable with insulation rated for, well, being a phone cable!!!

 

john..

 

John,

That is fine because you are dealing with insulated and sheathed or armoured and sheathed cables, this only applies with singles, sheathed cables are OK clipped direct, so they are OK in the duct with phone/alarm/data cable, as long as they are sheathed or SWA.

However, perhaps, the data cabling will be less happy with the electrical noise, we had to do this with some SWA (high current), for power to a remote building, & some SWA Cat5E on a site, for cameras, they were analogue camera's with converters to run down the CAT5E, then back again, don't ask I didn't design it, I just ended up supplying the km's of CAT5E and putting it in.

It all worked fine.

 

However, as I have said and you have suggested, singles and data cables in the same containment is a no-no.

 

I'm not going to comment on the prospect of cross talk to the data from the power, that is another kettle of fish, that may, or may not show up.

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Thanks for that!!

 

john..

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Legend!! thanks,

 

Yes agreed every sparky would have there own preference in options. I wouldn't be against a new CU as you said frees up space for later additions which I am already thinking about.

 

The earthing type appears to be TN-S, 100A, as for the consumer unit it was put in during the early 90s and is a MK SENTRY CONSUMER UNIT 7 WAY. I don't see any attach image button to post, except for the current and URL Media??.

 

All the spaces are taken:

1 - 6A - Ground and First floor lights - 12 Lights currently (I would prefer Ground and First to be on there own, however unsure of how simple that would be once the wires are looked at)

2 - 6A - Outside Lights - 4 Lights currently

3 - 32A - Kitchen Ring - 3 outlets plus a 5kw shower in the downstairs WC.

4 - 32A - Main Ground Floor Ring - 9 outlets

5 - 32A - Main First Floor Ring - 10 outlets and a 8.5K shower

6 - 32A - Cooker - 13A oven 4.6A hob

7 - 32A - Security Alarm / Sensors / Smoke Detector

 

The CU is to the right of the stairs in the Hallway, to the left of the stairs is the exterior wall which it could be taken to via the crawl space. However once outside it is near to the Gas Meter and Gas service line if that matters once outside? H+S?

 

The ground floor inside is concrete with tiles down. Outside the path is once again concrete until you reach the back garden lawn via the side passage. I was hoping to run it straight down along garden brick wall, which will have a concrete path laid over. which would be perfect to utilise the trench, added protection and ease.

 

I want the garage to power:

3x outlets on the inside

3x lights on the inside

Power a garage door opener

2x lights on the outside

1x outlet on the outside for the lawn mower

 

 

Cheers, Wayne

 

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slighting concerning that you have showers bodged in with sockets and security alarm / smoke detectors on a 32a...

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31 minutes ago, WaynW said:

I wouldn't be against a new CU as you said frees up space for later additions which I am already thinking about.

 

Erm yes, that CU is definitely not right, which does sort of lead to the assumption that whoever has done the electrical work there over the years has made a right old mess of it. I couldn't even give you an idea of what is involved or how much it would cost to to rectify this, let alone start adding to it.

None of what you want doing sounds difficult or complicated, but it does all want looking at by someone competent first.

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I see, it was done decades ago so don't know who or know how messy.

 

Can you elaborate for me on what you say by "not alright". Which aspects and anything else you may want to add.... I prefer to know what I'm honestly tackling.

 

The thought recently crossed my mind that it may be simpler and cheaper for a entire re-wire. Than try to sort what is there. 

 

Wayne

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20 minutes ago, WaynW said:

Can you elaborate for me on what you say by "not alright". Which aspects and anything else you may want to add.... I prefer to know what I'm honestly tackling.

 

The 2 showers should be on their own circuits, if they have been stuck in with the rings then it is anyones guess what sort of state the actual wiring to the showers themselves is like. Usually to split the lighting you would need some alterations making to the circuits if there are borrowed neutrals. Many people don't bother checking and just blindly put them on 2 circuits. If it hasn't been touched since the early 90's and it wasn't right even then I would guess (drawing from experience) that there will be a few minor issues to sort, along with rectifying the already bodged circuits.

 

Might not need a full rewire but it wouldn't hurt to leave your options open as rectifying faults can sometimes be not worth the hassle when you factor in the cost of just rewiring, but then you have to also consider the redecoration costs too.

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The showers were a later addition I'm guessing the person who did those. Simply had a loss of brain cells adding them on the ring. I am pretty sure I can get to those cables with relative amount of ease. So getting a new CU and separating them is annoying but not impossible. What Amp circuit should the showers be on?

 

Umm also what should the Amp be for the security. Sensory and smoke detectors. As they were a much much later addition and done by a full board sparky?!?!

 

From what I can guess so far the cost of new CU, sorting out showers, garage and mess. May in fact be less costly than saying strip it and re-wire

 

Ive looked around at costing for a full rewrire and I'm a little surprised at how low it was to what I thought... for a 3 bed semi, detached garage what price range do you guys think is the mean average. As I have seen job quotes and published advisors giving from 2-4K.

 

Im an apprenticed carpenter and very happy to do masonry and plaster, so don't mind the chasing damage. However some walls/floors are tiled and wouldn't want that level of expense.... couldn't afford it or the time unfortunately.

 

Wayne

 

 

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Hi Wayne,

 

1 hour ago, Andy™ said:

slighting concerning that you have showers bodged in with sockets and security alarm / smoke detectors on a 32a...

 

What Andy means is that;

 

1, The 5kw shower should really be on its own radial circuit in an ideal world.

 

2, The 8.5kw shower definitely should, and should most certainly not be not bodged in with a load of sockets on a ring.

 

3, Security Alarm / Sensors / Smoke Detector on a 32A... This is quite possibly the worst bit..... When you design a circuit, first off you decide what overcurrent protection you need for the load on the circuit. Only THEN do you decide what cable you need, based on quite a few factors, the primarly one of which, [i think it would be fair to say] is the overcurrent device used. The cable selected MUST be suitable and compatible with your choice of overcurrent protection, this is vital. The cables that feed your smoke detectors, would certainly not be suitable for connection to a 32A circuit breaker...

 

john..

 

 

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Hmmm, I didn't honestly think of that part as an issue. Just assumed the security company who sent the sparky knew what they were doing. What circuit breaker are these systems usually on??? This has got a back up power unit, control panel, 4 sensors, 3 window sensors and smoke detector. 

 

Should each shower have its own or both together?. I assume separate.

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55 minutes ago, WaynW said:

The showers were a later addition I'm guessing the person who did those. Simply had a loss of brain cells adding them on the ring. I am pretty sure I can get to those cables with relative amount of ease. So getting a new CU and separating them is annoying but not impossible. What Amp circuit should the showers be on?

 

Umm also what should the Amp be for the security. Sensory and smoke detectors. As they were a much much later addition and done by a full board sparky?!?!

 

From what I can guess so far the cost of new CU, sorting out showers, garage and mess. May in fact be less costly than saying strip it and re-wire

 

Ive looked around at costing for a full rewrire and I'm a little surprised at how low it was to what I thought... for a 3 bed semi, detached garage what price range do you guys think is the mean average. As I have seen job quotes and published advisors giving from 2-4K.

 

Im an apprenticed carpenter and very happy to do masonry and plaster, so don't mind the chasing damage. However some walls/floors are tiled and wouldn't want that level of expense.... couldn't afford it or the time unfortunately.

 

Wayne

 

 

I wouldn't be wanting a £2k rewire, :|

 

Here in the NW a 3 bed semi with separate garage would be around the £3&1/2 - 4k depending on spec. 

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Sounds like somebody bought a pre-populated CU with a random selection of MCB, which almost always have an excessive amount of 32A MCB's.  Then the "security" company just connected onto a 'spare' MCB in the fuse box that happened to be 32A. The manufactures instructions for electric shows have stated a dedicated circuit (probably including RCD), is required for many, many years now. I would suggest it wise to get a full inspection and test undertaken of the current installation, to verify exactly what is connected to what. It is not uncommon for fuse box descriptions to be different to what is actually physically connected. For an average domestic property a full inspection would typically be somewhere between half a day to a full day depending upon quantity and accessibility of accessories and how neat the fuse box wiring is. Probably somewhere between £150 to £250 depending upon actual duration and local labour rates. With this information you would then have a better idea of what remedial work is actually needed.

 

Doc H.

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10 hours ago, WaynW said:

What Amp circuit should the showers be on?

 

Well I think we're getting a bit too far into designing an installation that none of us has seen and someone else will be working on, so none of us need to know what size the shower MCB will be. It would depend on a few factors, but 32A would seem to be most likely.

 

10 hours ago, WaynW said:

From what I can guess so far the cost of new CU, sorting out showers, garage and mess. May in fact be less costly than saying strip it and re-wire

 

Maybe. Who knows, as I have said, without looking at the job we don't know. I don't know why you keep googling random stuff on the internet and assuming it applies to you. You need to get some electricians round for quotes.

 

10 hours ago, WaynW said:

Ive looked around at costing for a full rewrire and I'm a little surprised at how low it was to what I thought... for a 3 bed semi, detached garage what price range do you guys think is the mean average. As I have seen job quotes and published advisors giving from 2-4K.

 

2k is cheap for round your way. But you are still buggering about on the internet with vague ideas and guides. You need to get an electrician round to look at the job, not google rewire prices and then try to get someone else to design the installation.

 

9 hours ago, apprentice87 said:

3, Security Alarm / Sensors / Smoke Detector on a 32A... This is quite possibly the worst bit.

 

Who knows, might be fine. I had a 32A circuit doing outside lights and external power etc. It was simply a piece of 6mm² run through several switched spurs. May be nothing wrong as such with the breaker. Again, someone actually needs to look at the job as this is all speculation.

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I think the OP needs to get a proper EICR conducted but a local competent spark before he contemplates getting any changes made to the install...

 

and whats a "full board sparky"? (post #19)

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17 minutes ago, Murdoch said:

I think the OP needs to get a proper EICR conducted but a local competent spark before he contemplates getting any changes made to the install...

 

and whats a "full board sparky"? (post #19)

A day spent 'PAT' testing. :B 

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