Tail size from meter to cu

[Baker1988]

Hi every one how are u all on this nice monday morning. I wanted to ask i was at a job today and noticed that the tails from the meter to the consumer unit was in 10mm twin and earth and they was using the earth from the twin and earth to be the main earth From the cu and i did not think it is right and i suggested that they change the tails for 16 mm armoured cable ( i know u suppost to put 22mm tails in now but i though seen as it is a small flat 16 would be ok) and 10 mm earth cable it is a flat with 1 lighting circuit 1 ring final circuit and 1 cooker circuit and it is about 14 meter run from the meter to the consumer unit is this right or am i totally wrong any advice would be good

 

[Baker1988]

Sorry i mean i know it is suppost to be 25 mm tails sorry

 

[Ross1]

Are you saying there is a 10mm T & E leaving the meter because if there is that must look a right mess.

What size is suppliers fuse? I expect it would be 60A therefore 16mm double insulated tails are needed?

I`m sure there is sumthin in regs about Tails not to be longer than 3m as well.

 

[Baker1988]

Yes it comes out of the meter in 10 mm twin and earth and goes to a isolation switch about a meter away and then goes from the isolation switch about 13 meters to the consumer unit the meter is down stairs at the left side of the building and the consumer unit is up stairs at the right sude of the building so it is a lon run and yes i have been told that before that it should not be more then 3 meters if it is u have to put an isolation fuse in the line

 

[Baker1988]

It is a 80 amp supplyers fuse well so my work mate has told me i did not check the size of the fuse my self an i know meter tails are suppose to be less then 3m if they are more they should be in armoured cable and have a isolation switch

 

[tony mc]

There are a few things you need to look at here and what Ross has mentioned.

What is the earthing arragement for the premises?

 

[Ross1]

surley the meter cant have any DNO seals on it?

 

[Baker1988]

sorry but what do u mean by earthing arangement? as far as i can tell the main earth in the consumer unit is the earth from the twin and earth and that goes to the isolatin unit and then to the main earth block on the incoming supply. and no it hasnt got seal on it by the looks of it the cable has been in for a long time it is the old red and black colours

 

[malcolmsanford]

Is that isolation switch a switch or a switch fuse, if it's a switch fuse what size is that fuse?

From the meter to that swich fuse/isolator what size are those tails?

Unless it is a TNC-S system why do you lads think that 10mm T + E is not sufficient for a flat that as just 3 circuits?

 

[Ross1]

tony mc means TT or TNC-S etc

 

[Baker1988]

yes it is a switch with a switch with a fuse and the fuse is 60 amp from the meter to the isolator is the same twin and earth thats what i mean it definatly not right i think some one has come along in the past and just put 10mm t&e cos thats what they had in the van so they dont have to buy tails and im not saying the earhth is not good enough i wasnt sure thats why i am asking and also it is a tt system

 

[Ross1]

Is that isolation switch a switch or a switch fuse, if it's a switch fuse what size is that fuse?

From the meter to that swich fuse/isolator what size are those tails?

Unless it is a TNC-S system why do you lads think that 10mm T + E is not sufficient for a flat that as just 3 circuits?

i cant understand how you can acheive double insulation at points of termination at meter with a T & E cable. Never seen it before and is bad practice in my opinion.

 

[Baker1988]

i agree with ross i think it is bad practice too so am i right in suggesting to my boss that he needs to change the twin and earth for 16mm armoured cable tails

 

[Ross1]

25mm tails to the switch fuse, then 16mm from there on. earth must acheive under 200ohms preferably under 100. Others will prob have more to say on matter Baker1988, but i gotta go. Chaw 4 now

 

[malcolmsanford]

The tails from the meter to that switch fuse I would agree should be double insulated and as it is just a meter in length then no problems.

10mm T +E though can take 60amp on reference method C, so unless there is a good reason not to, that can stay, or you could fit a 40/45 amp fuse if the CCC don't work out.