Extending Meter Tails

jools · Feb 3, 2015

Two part question: Existing 16mm tails are over 6m in length from meter. They are encased in 32mm steel conduit running through a concrete floor and vertically up a block wall right upto the consumer unit. There is no place to install a de-rated switch fuse for isolation or protection. Is it sufficient just to mention this as a comment on the certificate when carrying out a CU upgrade?
The replacement CU would need to be moved downstream a further 2m as the existing wall is to be demolished. What is the best way to extend the tails as the cables will need mechanical protection and the joint will be inaccessible afterwards?

Leesparkykent · Feb 3, 2015

jools said:
Two part question: Existing 16mm tails are over 6m in length from meter. They are encased in 32mm steel conduit running through a concrete floor and vertically up a block wall right upto the consumer unit. There is no place to install a de-rated switch fuse for isolation or protection. Is it sufficient just to mention this as a comment on the certificate when carrying out a CU upgrade?
The replacement CU would need to be moved downstream a further 2m as the existing wall is to be demolished. What is the best way to extend the tails as the cables will need mechanical protection and the joint will be inaccessible afterwards?

You need to come up with a way of installing a new cable and a switch fuse IMO and don't say you can't as there is always a way but might involve more cost/time. Ain't any one else's problem if you haven't thought about this situation and priced the job wrong and now have dropped a clanger.

Anthony S · Feb 3, 2015

Its a job for a Qualified Experienced Electrician and your clearly not.

Plonker 3 · Feb 3, 2015

Whats the rating of the incoming fuse?

jools · Feb 3, 2015

It has an 80A rating

Plonker 3 · Feb 3, 2015

Is that the rating if the fuse inside the carrier, or what it says on the carrier?

Engineer54 · Feb 3, 2015

jools said:
Two part question: Existing 16mm tails are over 6m in length from meter. They are encased in 32mm steel conduit running through a concrete floor and vertically up a block wall right upto the consumer unit. There is no place to install a de-rated switch fuse for isolation or protection. Is it sufficient just to mention this as a comment on the certificate when carrying out a CU upgrade?
The replacement CU would need to be moved downstream a further 2m as the existing wall is to be demolished. What is the best way to extend the tails as the cables will need mechanical protection and the joint will be inaccessible afterwards?

Sounds like you'll need to find another route to the repositioned new CU and abandon the 32mm existing containment unless you can extend the floor chase to the new position. At least with a new cable and route you'll be able to find space for a switch fuse. Next thing you need to decide is what type of cable you are going to use to supply the repositioned CU....

I wouldn't be thinking about jointing single tails to be honest. If you intend extending the metal containment use one of the cables as a draw line to pull in new tails. You might have to pull the cables into the extended sections bit by bit as you are installing, if there are too many bends. Not a very good practice at the best of times, and no chance of ever being able to rewire in the future!!