Exporting Supply To Garage Extension, Cable Sizing

[ultinator]

Need to supply a cable for a garage extension,

'Plumber' has proposed 2 x 10mm T+E in 100mm ducting along with a water pipe, with no CU at the garage.

This will eventually be marketed as an annex which will include but no limited to, 1 shower (power unspecified), 1 electric water heater, possible multiple mounted wall heaters, macifier, lights and 12 sockets. The client at this point in time will also be storing 18 motorbikes inside so it could be used as a work shed for tools etc.

Would a 16mm armoured or 25mm armoured run in the ducting instead of the 2x 10mm T+E with a CU in garage be a more suitable choice taking volt drop into consideration??

 

[SYKRAPS]

You will need to specify a little more information please.

DNO supply type and size.

Extraneous parts in the garage?

Length of sub-main run and installation methods?

Total loading in the main house building?

Total loading in the garage for what you are doing and expected expansion?

Why no CU in the garage surely this is a deffinite requirement?

 

[Octopus]

Why is the plumber proposing ANYTHING, other than pipes and where he'd like the FCU for the boiler supply?

 

[ayrshirespark]

cable r
cable

If electric heaters etc and shower forget 10mm , 25mm safest bet but you'll need a cu in the garage

 

[Robert Turnbull]

I'm failing to see how you turn a armoured or 2 x 10mm's into a light circuit, shower circuit, socket circuit etc .......

Without a CU

Without considering regs

 

[ultinator]

TN-S
80A main fuse, 25mm
None
Installation Method D
40m run, Installation method in house B
Total load of entire installation expected to be within 80A

Is it a requirement? Presumably I would think so, with a separate earth electrode for the garage. Could you point me in the right direction of BS7671 so I can inform the client?

Appreciate the quick reply

 

[Octopus]

Have you joined a scheme yet as some of this is notifiable!!

 

[Sintra]

Why don't you take a look through BS7671 yourself then come back to us with your findings. Then we can point you in the right direction..

 

[ayrshirespark]

earth

Why an earth rod,a tns has an earth,.earth rod for tt , get an electrician in

 

[ultinator]

Proposed works for next year, so can be part of one of the scams.

Can't find specific regulation regarding extensions apart from the obvious (do danger, to persons, property, livestock) and existing installation must meet requirements of additions and alterations.

I would design it incorporating 16mm or 25mm (depending on loading) two core armoured through the 100mm ducting feeding a sub-main CU, rather than the plumbers 2 x 10mm T&E. Bearing in mind a water pipe is travelling in the same duct.

Have been advised of use of Earth rods as this surpasses the event of a fault travelling from the garage through the house. Any exposed/extraneous conductive parts can use the Electrode.

Any help would be appreciated.

 

[applesandppears]

Its funny that I have seen this post on here,

I done a similar job as part of an install not to long ago,

we used a 10mm cable twin and earth (grey one) in ducting.

Simple, three letters FCU. Avoids any consumer units so no need to notify anyone

Simples!! Hope this helps

 

[SYKRAPS]

Its funny that I have seen this post on here,

I done a similar job as part of an install not to long ago,

we used a 10mm cable twin and earth (grey one) in ducting.

Simple, three letters FCU. Avoids any consumer units so no need to notify anyone

Simples!! Hope this helps

Me thinks that you should read the thread from the begining before making such statements and if you have read the thread from the begining STOP giving advice

 

[Octopus]

Its funny that I have seen this post on here,

I done a similar job as part of an install not to long ago,

we used a 10mm cable twin and earth (grey one) in ducting.

Simple, three letters FCU. Avoids any consumer units so no need to notify anyone

Simples!! Hope this helps

If you have the regs you'll know that "showers" are notifiable - but I suspect you spend your money on feeding your horse.

 

[SYKRAPS]

Proposed works for next year, so can be part of one of the scams.

Can't find specific regulation regarding extensions apart from the obvious (do danger, to persons, property, livestock) and existing installation must meet requirements of additions and alterations.

I would design it incorporating 16mm or 25mm (depending on loading) two core armoured through the 100mm ducting feeding a sub-main CU, rather than the plumbers 2 x 10mm T&E. Bearing in mind a water pipe is travelling in the same duct.

Have been advised of use of Earth rods as this surpasses the event of a fault travelling from the garage through the house. Any exposed/extraneous conductive parts can use the Electrode.

Any help would be appreciated.

As Sintra says have a look at the BGB and list us your conclusions

 

[richy3333]

Need to supply a cable for a garage extension,

'Plumber' has proposed 2 x 10mm T+E in 100mm ducting along with a water pipe, with no CU at the garage.

This will eventually be marketed as an annex which will include but no limited to, 1 shower (power unspecified), 1 electric water heater, possible multiple mounted wall heaters, macifier, lights and 12 sockets. The client at this point in time will also be storing 18 motorbikes inside so it could be used as a work shed for tools etc.

Would a 16mm armoured or 25mm armoured run in the ducting instead of the 2x 10mm T+E with a CU in garage be a more suitable choice taking volt drop into consideration??

Let the plumber do the job and sign it off. FFS!

 

[ultinator]

Is there any advice (not FCUs everywhere!!) that may help me defeat a plumber who intends to use part p to take this work?

is there any justification in using 2x10mm cables instead of my proposed 16mm or 25mm cable?

Any help would be appreciated.

 

[Hiddo]

Its funny that I have seen this post on here,

I done a similar job as part of an install not to long ago,

we used a 10mm cable twin and earth (grey one) in ducting.

Simple, three letters FCU. Avoids any consumer units so no need to notify anyone

Simples!! Hope this helps

How does fitting a FCU make it non notifiable? Also I'd love to see that 10mm terminated into said FCU.

 

[SYKRAPS]

How does fitting a FCU make it non notifiable? Also I'd love to see that 10mm terminated into said FCU.

And a 13a fuse for an electric shower, 12 sockets, lights, heaters and future expansion lol

 

[richy3333]

If you have the regs you'll know that "showers" are notifiable - but I suspect you spend your money on feeding your horse.

Now that is funny! I thought Gyppo's had horses, the Polish have cabbage based food products?

 

[richy3333]

Is there any advice (not FCUs everywhere!!) that may help me defeat a plumber who intends to use part p to take this work?

is there any justification in using 2x10mm cables instead of my proposed 16mm or 25mm cable?

Any help would be appreciated.

Err, remind the PLUMBER its an ELECTRICAL job and he should restrict himself to unblocking toilets?

 

[ultinator]

Looking through our guide to the building regulations 2.1 design, can't find even a transparent reason for my choice of cable over his??

should meet the requirements of ADS.

Good client, could do with more decent work (new installs) like this one.

As always, appreciate the useful replies.

 

[richy3333]

Looking through our guide to the building regulations 2.1 design, can't find even a transparent reason for my choice of cable over his??

should meet the requirements of ADS.

Good client, could do with more decent work (new installs) like this one.

As always, appreciate the useful replies.

If you do a search on here you'll find a NAPIT guide to exporting the earth? Doubt the plumber would have that knowledge?

 

[SYKRAPS]

Is there any advice (not FCUs everywhere!!) that may help me defeat a plumber who intends to use part p to take this work?

is there any justification in using 2x10mm cables instead of my proposed 16mm or 25mm cable?

Any help would be appreciated.

Start off by working out CCC of the 10mm t+e over 40m and see if you feel its ok, then you will have 2 x 4mm cpc conductors (pressuming that 2 x 10mm t+e are for 2 seperate supplies) do you think that this is adequate for any extraneous earthing that is possibly required? Still don't see how you can do this with no CU????????

Ask for the plumbers spec so you can price on a level playing field, then post it pls pls pls

 

[GLENNSPARK]

Why is the plumber proposing ANYTHING, other than pipes and where he'd like the FCU for the boiler supply?

EXACTLY!!....didn`t we have something in here the other day about this kind of thing?....like plumbers gettin above their station.......

 

[thekingiam]

uhh what just happened? someone told op he should calculate supply cable size then he looks in a book and decides to use 10 mm as the plumer knows best?

 

[Johnuk]

tell this plumber to stick to the water, let the men do the really work, i dont now why the hell a did part p, with all elses dumb --- around, we have been to so many jobs were elses people think doing the pat p course make them a electrician

 

[SYKRAPS]

tell this plumber to stick to the water, let the men do the really work, i dont now why the hell a did part p, with all elses dumb --- around, we have been to so many jobs were elses people think doing the pat p course make them a electrician

You wouldn't find me messing with water or gas thats for sure

 

[Sintra]

1. SWA has mechanical protection so a better option as you can eliminate the need for RCD protection on the sub main.
2. Do you want to extend the equipotential zone or make outbuilding stand alone TT. I personally would more than likely extend zone as its TN S and install EMT in outbuilding.
3. IMO a CU in the outbuilding is a must.
4. You need to calculate size of sub main and type and size of overcurrent protective device to meet disconnection times and volt drop.

Just a few points to get you thinking.

 

[thekingiam]

uhh what just happened? someone told op he should calculate supply cable size then he looks in a book and decides to use 10 mm as the plumer knows best?
looking at ops previous posts he has done cu changes etc etc i am starting to believe he is either someone ignoring part p and hasn't the knowledge an electrician should have or is himself a plumber and we are telling him how to do electrics?

 

[applesandppears]

I was told by a mate at the pub that as long as you dont create a new circuit by adding a CU then it isn't notifiable. Anyway the 10mm cable WAS too big to terminate so just a little bit of creativity with a connector block and some 2.5 twin and earth sorted that problem. Well notifiable or not at least it alleviates any need for testing as a simple functional test works and its all protected by a 13A fuse which is easy to replace, was nice enough to leave a small pack of them behind as about 3 of them went faulty when I turned the heater on so just left that off when i went to the pub at the end of the day with my cash. Simples

 

[Johnuk]

You wouldn't find me messing with water or gas thats for sure

same here with the plumbing side,

 

[ultinator]

never said i was using 10mm, that is what a part p 'sparky' aka greedy plumber, playing out of his field undercutting others has stated should be used to the client who is in need of a good hiding if they want advice on electrics from a plumber... dont wish to start a riot just trying to consolidate on regs and ideas to point my finger at when questioned why it should cost more...some people seem to feel that 'less' is more.

 

[GLENNSPARK]

same here with the plumbing side,

yes....well gas is smelly stuff for a start.....there again so is bog water.....
agreed...leave it to `them over there`....

 

[serpico4321]

2. Do you want to extend the equipotential zone or make outbuilding stand alone TT. I personally would more than likely extend zone as its TN S and install EMT in outbuilding.


Had this situation on a recently completed job, when DNO upgraded main fuse too 100A he said a spike will be needed for the outhouse, said it didn't matter if EMT was installed or not, regs said fault current couldn't pass through existing build (about 40m away) though he couldn't tell me which reg and my employer reckoned EMT would've been more than the earth electrode.

still never found why, in a book anyway.


Any ideas ?

 

[Engineer54]

This whole scenario just beggars believe!! I can't make up my mind who's worse, the plumber or the OP...

I'm staying out of this for the time being, at the moment your all on a hiding to nothing!! lol!!

 

[Engineer54]

2. Do you want to extend the equipotential zone or make outbuilding stand alone TT. I personally would more than likely extend zone as its TN S and install EMT in outbuilding.


Had this situation on a recently completed job, when DNO upgraded main fuse too 100A he said a spike will be needed for the outhouse, said it didn't matter if EMT was installed or not, regs said fault current couldn't pass through existing build (about 40m away) though he couldn't tell me which reg and my employer reckoned EMT would've been more than the earth electrode.

still never found why, in a book anyway.


Any ideas ?

Whoever told you that, (and it was probably the meter guy) was talking out of his arse, total load of nonsense!!

 

[serpico4321]

Whoever told you that, (and it was probably the meter guy) was talking out of his arse, total load of nonsense!!

it beggars belief that you can insult people who have genuine questions from scenarios in the real world and still not provide justification. Not all of us have had the opportunities others may have.

 

[Sintra]

2. Do you want to extend the equipotential zone or make outbuilding stand alone TT. I personally would more than likely extend zone as its TN S and install EMT in outbuilding.


Had this situation on a recently completed job, when DNO upgraded main fuse too 100A he said a spike will be needed for the outhouse, said it didn't matter if EMT was installed or not, regs said fault current couldn't pass through existing build (about 40m away) though he couldn't tell me which reg and my employer reckoned EMT would've been more than the earth electrode.

still never found why, in a book anyway.


Any ideas ?

That DNO guy obviously knows something more than I do. Perhaps I have got it wrong for all these years believing electricity takes the path of least resistance.

 

[serpico4321]

Sintra,


Thankyou!


so, TN-S + EMT means fault path is comparatively low to that of a TT plus no soil integrity to allow for.


am I right to believe there is no specific reg for this instance just that the fault path is preferable to be as low as possible to meet ADS?

RCDs are beautiful things.


Kind regards

 

[Engineer54]

Whoever told you that, (and it was probably the meter guy) was talking out of his arse, total load of nonsense!!

it beggars belief that you can insult people who have genuine questions from scenarios in the real world and still not provide justification. Not all of us have had the opportunities others may have.

There is a simple answer to that statement then isn't there, if your not capable of getting even the basics straight, then you shouldn't be taking on that work in the first place!!