Rewiring to a garage

[butchtaylor909]

Hi everyone,
I have been asked to look at someones Garage for them as they want to be able to have more "stuff" in there.

currently it is powered by a 2.5 t&e run from the house CU straight to a 2g pattress. But they want a separate CU in the garage.

my initial idea was to henley block and put a fused switch in and run 10mm SWA from that. however the house CU is in the middle of the house so would need a good 3m run in the house and another 3-4m to get it underground to the garage.
the customer asked if the was anyway to not use SWA through the house? so i mentioned about adaptable boxes.
Now my question is could i run 10mm 3core (to maintain the CPC size and not T&E) to an adaptable box mounted externally then gland some 10mm SWA to that terminated on the inside, and earthing the steel? and then repeat on the garage side?
Providing all my tests are fine is there any issue with this?

 

[Octopus]

So the customer will allow 10mm T&E, but not SWA...... hum

what is the 10mm 3 core you refer to? Singles?

 

[Pete999]

Leave the tails of the SWA long enough to reach the CU after you terminate it at the AB

 

[westward10]

Installing a separate switch fuse removes the single point of isolation assuming there already is one.

 

[butchtaylor909]

So the customer will allow 10mm T&E, but not SWA...... hum

The armour obviously limits the flexibility of the SWA and therefor hinders the routing of the cable. Concrete floors so no cavity to send it under. He wants to try and keep things as simple as possible. and to be honest so do i. 3m of flex is easier to route through a house than 3 m of SWA. they have had a recent rewire and they have had conduit fiited into the wall along the proposed cable route, i have checked and i can get a 10mm 3core down it but not a 10mm SWA. Using this means no need to channel and re-plaster or surface mount and put in trunking. Plus works out cheaper.

what is the 10mm 3 core you refer to? Singles?

10mm cable that has 3 cores with all csa being 10mm! like industrial YY control cables,can get rubber or PVC versions of it, from my previous job experience i know it goes over 10mm in CSA. If it was singles it would not be 3 core, it would be 3 single core cables surely!

Leave the tails of the SWA long enough to reach the CU after you terminate it at the AB

that is what i thought but having to strip about half of the overall length seemed a bit wasteful. If he lets me or if there is no other way i can terminate straight to the switch fuse removing the need to use ABs or leave the inner sheath running through the house for 3 m

Installing a separate switch fuse removes the single point of isolation assuming there already is one.

Why not henley block after the isolation switch? which is what i was intending thus it keeps a single point of isolation. And with a switch fuse it allows for the garage/workshop to maintain power in the event of anything tripping in the house. Prevents needing to factor in discrimination for the garage CU potentially tripping the house CU too.

thanks for the replies so far.
Still fairly new to this so glad for the advice but i will question most things until i am sure.

 

[Pete999]

The armour obviously limits the flexibility of the SWA and therefor hinders the routing of the cable. Concrete floors so no cavity to send it under. He wants to try and keep things as simple as possible. and to be honest so do i. 3m of flex is easier to route through a house than 3 m of SWA. they have had a recent rewire and they have had conduit fiited into the wall along the proposed cable route, i have checked and i can get a 10mm 3core down it but not a 10mm SWA. Using this means no need to channel and re-plaster or surface mount and put in trunking. Plus works out cheaper.


10mm cable that has 3 cores with all csa being 10mm! like industrial YY control cables,can get rubber or PVC versions of it, from my previous job experience i know it goes over 10mm in CSA. If it was singles it would not be 3 core, it would be 3 single core cables surely!



that is what i thought but having to strip about half of the overall length seemed a bit wasteful. If he lets me or if there is no other way i can terminate straight to the switch fuse removing the need to use ABs or leave the inner sheath running through the house for 3 m



Why not henley block after the isolation switch? which is what i was intending thus it keeps a single point of isolation. And with a switch fuse it allows for the garage/workshop to maintain power in the event of anything tripping in the house. Prevents needing to factor in discrimination for the garage CU potentially tripping the house CU too.

thanks for the replies so far.
Still fairly new to this so glad for the advice but i will question most things until i am sure.

Route the SWA outside @ CU terminate into an Adaptable box outside, suitably IP rated and run 10mm twin with cpc from box to CU @ garage terminate SWA directly into New Garage unit, rocket science it is not.

 

[Pete999]

The armour obviously limits the flexibility of the SWA and therefor hinders the routing of the cable. Concrete floors so no cavity to send it under. He wants to try and keep things as simple as possible. and to be honest so do i. 3m of flex is easier to route through a house than 3 m of SWA. they have had a recent rewire and they have had conduit fiited into the wall along the proposed cable route, i have checked and i can get a 10mm 3core down it but not a 10mm SWA. Using this means no need to channel and re-plaster or surface mount and put in trunking. Plus works out cheaper.


10mm cable that has 3 cores with all csa being 10mm! like industrial YY control cables,can get rubber or PVC versions of it, from my previous job experience i know it goes over 10mm in CSA. If it was singles it would not be 3 core, it would be 3 single core cables surely!



that is what i thought but having to strip about half of the overall length seemed a bit wasteful. If he lets me or if there is no other way i can terminate straight to the switch fuse removing the need to use ABs or leave the inner sheath running through the house for 3 m



Why not henley block after the isolation switch? which is what i was intending thus it keeps a single point of isolation. And with a switch fuse it allows for the garage/workshop to maintain power in the event of anything tripping in the house. Prevents needing to factor in discrimination for the garage CU potentially tripping the house CU too.

thanks for the replies so far.
Still fairly new to this so glad for the advice but i will question most things until i am sure.

I thought you were terminating the SWA directly on the outside wall behind the CU you obviously cant strip yards of armour off the SWA and run that internally, jeez mate get a grip

 

[butchtaylor909]

Route the SWA outside @ CU terminate into an Adaptable box outside, suitably IP rated and run 10mm twin with cpc from box to CU @ garage terminate SWA directly into New Garage unit, rocket science it is not.

Yeah thats along the lines of what i was thinking to do. Just was not sure if there was any issues with doing it like that.

I thought you were terminating the SWA directly on the outside wall behind the CU you obviously cant strip yards of armour off the SWA and run that internally, jeez mate get a grip

i even mentioned in the OP that it would need 3m of cable inside the house due to where the CU is so i was wondering why you would suggest stripping 3m of armour off

 

[Geordielad]

If there's already conduit in the house to run through, why not just extend this to the garage and run singles the whole distance?

 

[Pete999]

Yeah thats along the lines of what i was thinking to do. Just was not sure if there was any issues with doing it like that.



i even mentioned in the OP that it would need 3m of cable inside the house due to where the CU is so i was wondering why you would suggest stripping 3m of armour off

I'm not suggesting that, I thought it was mentioned earlier, I may have misunderstood the bit about 3mtr inside, again I assumed it was a 3 mtr run from the CU to the point where you could enter the garage space

 

[telectrix]

if you have conduit installed for the 3m inside the house, run it 10mm singles to ad. box. then joint to SWA, remembering that the armour needs to be earthed at the house end if not used as part of cpc, or both ends if it is. earthing nuts come in useful here.

 

[butchtaylor909]

Now would you put it as an non-rcd protected way on the House CU (would need a new CU as all ways are in use) or go for the Henley block split and switch fuse like i was thinking about?

 

[telectrix]

how is the cable to be installd in the house? is it <50mm from surface of a wall? if not, RCD protection is not required.

 

[butchtaylor909]

In metal conduit that is run along the bottom of the kitchen behind all the cupboards. no idea how deep with out ripping the new kitchen out and knocking hole in the wall to measure.
But if i can prove its earthed (or provide one) there is no need to RCD regardless of depth.

The next question is which is best
10mm T&E +CPC
10mm 3 core
or 3x 10mm single core

or is it all 6 and half a dozen.

 

[westward10]

Unless it has earthed containment.

 

[Pete999]

In metal conduit that is run along the bottom of the kitchen behind all the cupboards. no idea how deep with out ripping the new kitchen out and knocking hole in the wall to measure.
But if i can prove its earthed (or provide one) there is no need to RCD regardless of depth.

The next question is which is best
10mm T&E +CPC
10mm 3 core
or 3x 10mm single core

or is it all 6 and half a dozen.

10mm2 T&E +cpc?

 

[butchtaylor909]

I don't want to be offensive but from what you are asking you don't seem to have a clue what you are doing.

No your right i have never had to do a garage rewire where the CU is so far in the house. normally its a simple job of having a AB outside and running through to the CU, but as this is the first time i have come to a job like this i wanted to ask for advice and not just go at it cowboy fashion like a lot of people do.

 

[butchtaylor909]

but at least i am trying to get the job done correctly with some SWA and not with a bit of 2.5 t&e buried bare to the garage like the last dodgy spark did

 

[butchtaylor909]

10mm2 T&E +cpc?

yeah sorry getting tired, up too early and not enough sleep last night.
does the bonding conductor not need to have a minimum csa of 10 mm to an outbuilding fed form a dwelling with a pme system? i put cpc by error and not pbc.
but without going round again off top of my head i cannot remember if there were any extraneous conductive parts. think the water was plastic.

 

[telectrix]

earrth the metal conduit. install 10mm singles.