Advice on Cable to use from Meter to CU

[neilma]

Hi all,

Just a couple of quick questions if possible....

I have asked Southern Electric to move my meter (from inside to outside) and for this I have purchased a new cabinet. I need to run the cable(s) from the meter to the consumer unit and get an electrician to connect them up on the day they move the meter. I want to get the cable installed before they turn up as I have a plasterer arranged to clear up the mess. I seem to be getting conflicting views on what to use as the CU will be over 3 meters away from the meter when its in its new position and as such I cant just run the tails from the meter to the CU (so I am informed)

Can anyone let me know what cable(s) to purchase?

(The cable run will come from the back of the cabinet into the house then up some trunking (in the wall) into the ceiling void then into the back of the CU). The total cable length should be around 5 - 6 Meters.

Some places have said to use 25mm Meter Tails (with a 16mm Earth), others have said 16mm T&E.

Southern Electricity also said I need to put a switchfuse in the meter cabinet to protect the cable length - would that be a 60A/80A or 100A? and can you recommend one to buy?

Sorry for all the questions, but i'd appreciate some clarity!!

Cheers

 

[Big_Spark]

First of all, what is the rating of the main fuse in your supply?

You need to determine this as the switchfuse you install adjacent to the meter should be of equivilent or lower rating. If you have a 100A supply, then it makes sense to have a switchfuse with a 100A HRC fuse in it, unless your loading of that will be significantly lower then you could drop the fuse rating to 80A or even 60A.

Regarding the cable from the switch fuse to the consumer unit. If you have a 100A supply then you only have one sensible choice, and that is 25mm 3 core SWA. 16mm T&E does not have sufficent rating for this loading and therefore should not be used if your main fuse rating is in excess of 60A (16mm T&E has a maximum rating of 69A for the installation method you are proposing).

Hope this helps to unmuddy the water.

 

[neilma]

Thanks for your prompt reply

The incoming fuse is 100A

The tails that currently leave the meter go through an old looking crabtree 500V 60A switch (black bakelite looking if that helps) before going into the CU. I take it I cant (or shouldnt) re-use that and should just get the switchfuse? Would 60amp be ok (and thus then the 16mm T&E) as that is what it seems I am currently using?

If the SWA is the way to go, would the Live,Neutral and Earth all go through the same cable? (i'm trying to avoid using this as it seems quite hard to work with tho

Thanks again for your help

 

[Big_Spark]

You need to look at the supply you will be using.

60A may be sufficient, but maybe not.

Post a list of all your circuits and their ratings and how many ways the consumer unit is.

 

[neilma]

8 Way consumer unit (but looking to upgrade it to a 11 way in the near future....

3 x Lighting circuits (with 5A fuses)
1 x small Ring (20A Fuse)
2 x Rings (30A Fuses)
1 x Cooker (30A Fuse)
1 x Immersion Heater (30A Fuse)

 

[Big_Spark]

Neilma, I presume they are the old BS3036 rewireable type..or are they cartridge fuses? Just curious really

Anyway, I would upgrade the board to take MCB's and RCBO's, far safer. The board I would leave with a 100A supply, if you upgrade later, and want to add more circuits, you know the supply will be able to cope without any work to upgrade it.

 

[neilma]

Rewirable cartridges (hence me upgrading )

Ok - i'll go the 100A route.

So I need a 100A Switched Fuse and the the SWA cable. And I use all three cores for the L,N and E? i.e. I dont need to run any other cables for earth or anything?

Thanks VERY much for your help!

 

[plugwash]

yes its advisible to use 3 core armoured and use a core for earth with such large sizes

but you should still earth the armour as well
you should be able to do most of the wiring work yourself though the boad may want a sparky to do the final linkups when they move the meter

also you will save yourself a lot of trouble if you use a METAL cu and a METAL switchfuse unit so you can terminate the SWA directly to them