Copper sheathed cable - Consumer unit

[1066]

I have recently purchased a small, 1950’s purpose built studio flat. I want to update the wiring.

At present the flat is fed from an individual meter in the communal hall by copper sheathed 2-core cable. This feeds into an old fashioned metal fuse box with re-wirable fuses.

I want to fit a new consumer unit with RCD to supply a small ring main in the kitchen. I also want to fit a new cooker point and an electric shower.

My problem is – should I fit the new consumer unit in addition to the old one taking a feed off the main incomers, if so how do I go about connecting an earth to the copper sheathing or should I scrap the old unit, if so how do I connect the existing copper sheathed cables to the new unit.

1066

I intend to get professional help to connect up the consumer unit but any advice would be appreciated.

 

[plugwash]

id scrap the old unit and replace it with a metalclad CU (easier to fit glands to theese than plastic units)

that cable sounds like pyro and provided it is glanded off well it should be prety trivial to move into the new CU

if its not glanded or there is a problem with the glanding that has allowed water ingress you will need to do one of the following

1: cut back and re-terminate in a new CU plced further back along the cable
2: cut back and terminate in an adaptable and then run a new cable of appropriate rating to the CU
3: replace the run

 

[securespark]

id scrap the old unit and replace it with a metalclad CU (easier to fit glands to theese than plastic units)

Indeed, a metalclad unit would make it easier to ensure earth continuity too.

As you are relying on the sheath for the earth connection, this is imperative.

Perhaps running an additional earth conductor from the main earth terminal of the installation would be advisable.

Also, updating of existing (or not as the case may be!) earth bonding to services, gas, water pipes etcetera, and as you are installing a shower, upgrading bonding in the bathroom, too.

 

[Big_Spark]

If the Pyro is more than 35 years old it will need to be replaced, this is because it will have Imperial pots and glands on an Imperial cable..and as such it will not comply with BS7671.

The cable should be Tested and Inspected by a qualified Spark so ensure the cable is even safe to continue using. It should be remembered that the older Imperial Pyro Pots were filled with a compound which did degrade over the years, and there is a real chance that disturbing the pot to replace the Consumer Unit could cause damage that will degrade the cables ability to do it's job or simply introduce a fault that will require it's replacement regardless.

The other thing to consider is will it actually be able to support the load you now wish to draw through it, you should look into this very seriously, it may only be a Studio flat, but you may have a supply at the meter incapable of supplying what you want.

Think about everything twice, this is a potentially dangerous situation if proper preparation and caution is not taken.