New Separate Breaker for Garage?

[iDIY]

Hi

I am building a new detached garage with a single room art studio above it. I have removed the original prefab garage, disconnected the socket and lighting twin& earth cables from the house consumer and removed them from where they were just buried in the soil with no protection ?

I have dug a deep trench from house to garage and buried a trunking marked up with appropriate electrical warnings along its length.

I will run a 30 or 40 amp Cable from the house to the garage and then get a certified electrician to install a separate circuit breaker in the house and a new consumer unit in the garage from where the garage and studio lighting will be connected.

My question is this, can the certified electrician break the seal on the electronic meter in the house and add in a new pair of tails to feed the new circuit breaker or will I have to get the electric company to send out an engineer ?

 

[ban-all-sheds]

There is no such thing as a "30 or 40 amp cable". Cables are of particular sizes, and the amount of current any one can vary varies dramatically according to how it is installed and how long it is.

Please consult your electrician over the size (and type) you should use, and if you've not backfilled the trench yet then do not do so until he has seen it.

The CU in the garage should be supplied via a switchfuse in the house, not a circuit breaker.

Seals on the meter should not be broken.

Some electricians will break the seals on the service fuse in order to pull it to isolate the supply so that this type of work can be done, some will not. It depends on a combination of their attitude (it's a dubious activity), the type of cutout you have, and the attitude of the DNO. You'll need to ask your electrician.

In fact, you need to get your electrician engaged asap - this work is all notifiable wrt Building Regulations, and you cannot expect him to certify things he's not been responsible for, to say he did work which he did not, to take responsibility for your work, etc.

Plus there's the issue of Building Regulations compliance for the whole project. When you applied for approval for the build, what did you say, or by default allow them to assume, would be the way you would ensure compliance with Part P? Because if you said, or tacitly agreed, to one thing, and then you go and do something different your Building Control will be p****d off, and could well refuse you a completion certificate.

 

[iDIY]

I was trying to keep it brief as the only question is the one about the seal on the meter?

No building has started yet, I am still clearing and preparing the site so BCO has not even visited yet. The trench, trunking and markings exceed any regs requirements.

 

[ban-all-sheds]

I was trying to keep it brief as the only question is the one about the seal on the meter?

OK.

My question is this, can the certified electrician break the seal on the electronic meter in the house

No.

 

[ban-all-sheds]

No building has started yet, I am still clearing and preparing the site so BCO has not even visited yet.

But have you submitted your Building Regs application yet?

The trench, trunking and markings exceed any regs requirements.

Be that as it may it would be wrong to expect any electrician to just take your word for that.

 

[iDIY]

But have you submitted your Building Regs application yet?

Yes, but they don’t do the first site visit until the foundations are dug.

Be that as it may it would be wrong to expect any electrician to just take your word for that.

I have pics and obviously the content of the trench is visible from both ends. If that’s not enough I can soon find a new electrician.

 

[flameport]

If that’s not enough I can soon find a new electrician.

What if the contents of the trench are not acceptable?

 

[iDIY]

What if the contents of the trench are not acceptable?

Have you actually read the requirements for buried cables? It doesn’t even need a duct, a suitable armoured cable can be buried as is. All I have done is provide a duct for a suitable armoured cable to be pulled through.

 

[oldbutnotdead]

Regarding your original question- presumably you want the supply to the outbuilding not coming from the house CU (for all sorts of good reasons). So what you need is some Henley blocks between your meter output and your house CU and then a circuit breaker (in an enclosure of course) to protect the cable to the outbuilding.

First job for you is get on to your electricity supplier and ask them to fit an isolator after the meter. Some do it for free, some charge £50. Once that is done, your electrician can do whatever connecting is required without having to interfere with the service fuse (which is dangerous).

Sort of like this (bit messy but I didn't do it )


As for the rest- what b-a-s said, it is all notifiable work, you may not have done yourself any favours with your ducting (SWA is the weapon of choice for buried cable, whoever does the volt drop calcs may have to derate it cos it now won't get any cooling effect from direct contact with the soil). While you are doing the job, put in the chunkiest cable you can afford (within reason) - if you are planning on heating yon flat with electricity that'll suck up a fair bit of current. Add a 10kw electric shower as well and you're up to 50 amps before adding any capacity for power tools in the garage.

EDIT- Art studio eh- probably scratch the shower then but you'll still need heat and while you're at it consider aircon (to maintain constant temperature/humidity) if you're going to be working with or storing oil based art

ANOTHER EDIT- the requirements for backfilling cable trenches are quite specific. With your duct the requirements will be different- (buried direct you'd have 100mm of sand below and above the cable, then marker tape, then slab protection- ideally saying DANGER ELECTRIC on it- then more marker tape, then backfill to 150 below ground then marker tape then topsoil). Your duct - pea shingle below and above then tape then slab then tape then backfill then tape then topsoil. Also keep an eye on minimum bend radius for the SWA

 

[JohnW2]

ANOTHER EDIT- the requirements for backfilling cable trenches are quite specific. ....

Most, if not all, of the 'specifics' I have seen are guidelines, rather than 'requirements'. Off the top of my head (separated from BYB at the moment!), I cannot think of anything particularly 'specific' in the actual regulations.

When one sees what DNOs sometimes get up too (a friend of mine recently stumbled across an incoming cable only about 9" deep in his flower bed), one sometimes wonders 'why we bother'

Kind Regards, John

 

[oldbutnotdead]

Most, if not all, of the 'specifics' I have seen are guidelines, rather than 'requirements'. Off the top of my head (separated from BYB at the moment!), I cannot think of anything particularly 'specific' in the actual regulations.

When one sees what DNOs sometimes get up too (a friend of mine recently stumbled across an incoming cable only about 9" deep in his flower bed), one sometimes wonders 'why we bother'

Kind Regards, John

Took me ages of ferreting on t'internet for detail- and I can't find the thing now! Certainly the electrician who did all the notifiable bits was insistent on the sand bed/cover for the cable and the solid protective layer- I used bricks mostly.

 

[JohnW2]

Took me ages of ferreting on t'internet for detail- and I can't find the thing now! Certainly the electrician who did all the notifiable bits was insistent on the sand bed/cover for the cable and the solid protective layer- I used bricks mostly.

Even most of the guidelines don't require a 'solid protective layer' unless there are unusual and specific risks of disturbance. The regulations themselves are, if I remember correctly, extremely vague, talking in such terms as 'adequate protection against mechanical damage'. I should be reunited with my book later tonight, so can check.

As with so many such things, the most important thing is common sense.

Kind Regards, John

 

[ban-all-sheds]

If that’s not enough I can soon find a new electrician.

And that approach was preferable to involving an electrician who you are going to have to use anyway, why, exactly?

 

[iDIY]

Well I have had quotes from 3 sparks so far. One says the SWA feeding the new CU in the garage needs a double pole switch with fuse at the house end. Another says it only needs a double pole switch with no fuse, the third is suggesting the SWA can be connected direct to a new breaker in the house CU. All are qualified certified sparks. Surely they can’t all be right ???

 

[flameport]

One says the SWA feeding the new CU in the garage needs a double pole switch with fuse at the house end.

That is one option

Another says it only needs a double pole switch with no fuse,

Not acceptable. Where did they intend connecting it without any fuse?

the third is suggesting the SWA can be connected direct to a new breaker in the house CU.

Another valid option.