Pre planning garage

[mylittlehouse]

Hello all
I will be putting down my living room floor and want to put in the cable ready to go to the garage.
It will come direct from the meter to the garage going under the house as the meter is in the living room.
There will be a split box cannot remember the name as one 25mm supply goes to the dist board in the hall.
At the meter there is a earth supplied from the lek company that is combined with the neutral.
So I want to put in a cable ready for the garage connection to the meter ready for the electrician to connect up when the garage is built.

My question is should I run steal wire armour from the meter at the front of the house and out of the rear air brick.
Is steal wire armour allowed to be installed along a brick wall using P clips rather than burying it under the pavement and new lawn/flower beds.
Does the the cable under the house need to be steal wire armour or can it be twin and earth that will change to steal at a junction box just before going outside
What size cable should I run ready in place.
Do I need a separate earth or will the earth in the steal service
I will not be connecting any of this up but just want to put the cable I place to save pulling up the floor later.
The reason I cannot take the connection from the existing dist board is that it is full to the brim and a separate dist board for the garage is a nice idea.
Thanks all

 

[mylittlehouse]

Or would I be better of getting a fused 13 amp spur to the garage to feed an electric garage door double socket and some lights?
Thanks

 

[PrenticeBoyofDerry]

No run The SWA cable, I would not bother with any cable joints under the floor, have the cable run in one full length.
The cable core size would depend on distance of the cable route and the load you required.
If you get three core cable one of these cores as well as the armour can be connected to earth.
Cable does not need to be buried but must be fitted to a secure structure such as a wall but not a fence.

 

[mylittlehouse]

That's good to know so I can put the cable in place ready for the person to install one day.
The distance is about 25 meters but I can measure it exactly.
The only power used will be a few power tools, drill, lights, electric garage door, lawnmover not all at once though
Thanks for your reply so quickly

 

[Aragorn84]

Cable does not need to be buried but must be fitted to a secure structure such as a wall but not a fence.

Heh, that'll be another thing the "electrician" who rewired my garage made an arse of then. SWA runs down the side of the house, Pclipped on, then up and along the top of the garden fence for 3-4meters then down into the garage.

 

[PrenticeBoyofDerry]

along the top of the garden fence for 3-4meters then down into the garage.

Not an ideal fixing point, as the fence is not considered a suitable safe structure.

 

[PrenticeBoyofDerry]

That's good to know so I can put the cable in place ready for the person to install one day.
The distance is about 25 meters but I can measure it exactly.
The only power used will be a few power tools, drill, lights, electric garage door, lawnmover not all at once though
Thanks for your reply so quickly

If you install a
lighting circuit at 6A
A socket circuit at 32A
At 25 metres you will require at 4.00mm SWA cable with cable clipped direct.
If the cable is buried you will need 6.00mm SWA.
The difference in material cost between 4 and 6mm will be about 50p per metre.
I would go for 6.00mm it will give some extra load allowances.
I assume all your power tools are 13A plug in type and not hard wired?
Could you tell us the type of earthing arrangement you have in the house and what demand is already at the board?

 

[Aragorn84]

How big is the garage?

Whats it going to be used for?

If its a building where your going to park a car or store junk you wont need much, where if its likely to be used as a workshop, its a different story.

Personally, for my use case, i'd want to have it done as a proper submain, using 10mm cable and switchfuse off the meter tails.

As was pointed out to me recently in another thread, if you use 6mm then you'll probably end up on a 40A breaker at the house CU, but then you dont have enough discrimination between the 32A breaker in the garage, and the 40A breaker in the house Using a switchfuse as i described above which would give you discrimination, will prove problematic finding a suitably rated fuse to protect a 6mm cable.

 

[plugwash]

If discrimination was really a big deal in a domestic situation we wouldn't have type B breakers in CUs behind BS1362 fuses in plugs. Nor would we have RCDs at the CU with only overcurrent protection downstream.

 

[Aragorn84]

But doesnt the wiring regs stipulate that discrimination must be taken into account when designing a circuit?

 

[mylittlehouse]

I think it will prob be better after reading all of this to get the electrician to come out and quote me for putting the cable in place ready for connection then when it comes to connection they cannot say its to small or not in the correct place as they already put it in place and calculated the correct way to connect everything up.
if the tails on the meter will be used it needs to go under the floor if they decided to take it from the current dist board then no cable needs to go in at all.

 

[SUNRAY]

Lay in a 50mm duct, its future proof