Meter tail length 10 metres in communal area?

[DaveS79]

Hi all

What is the situation in regards to excepted meter tail lengths for apartment installs. Changing board to 18th ed so all new certification required but meters are in landlord area and about 10metres from apartment DB. My reading of regs says 3M max tails but how is this possible in this situation.  For what it's worth fuse is bs7671 60/80 amp and tails are 16mm this seems adequate from my calculations 

 

[Sharpend]

Don’t think the fuse is a BS7671? 
the tails are fed usually from a ryefield board to local consumer unit- where is this fuse you speak of? 

 

[Murdoch]

what is wrong with the existing tails? and I don't think your reference number for the fuse is correct

 

[DaveS79]

Sorry lads predictive text it's a bs1361 I think I've sussed it gonna take deeper look I think it's a communal board and tails going to Fuse to meter then back to board ( on load side ) so this is in effect my tails and not exceeding 3metres. Going to take a closer look

 

[binky]

it's not so much the length of the tails, it's the lack of an incoporated cpc in the cable for the submain. 

 

[Andy™]

tails can be as long as they want. only requirement is if its over 3mtr (sometimes 2 or other depending on DNO) then you have to install your own fuse as you cant rely on theirs

it's not so much the length of the tails, it's the lack of an incoporated cpc in the cable for the submain. 

nope. no requirement for the cables to have a cpc within the cable. with the exception of SWA and some others, then you can easily hit the cable and damage a line without touching the cpc or the neutral so nothing will trip and there is no fault current. RCD for additional protection cant be used as you then cant comply with 314

 

[DaveS79]

tails can be as long as they want. only requirement is if its over 3mtr (sometimes 2 or other depending on DNO) then you have to install your own fuse as you cant rely on theirs

nope. no requirement for the cables to have a cpc within the cable. with the exception of SWA and some others, then you can easily hit the cable and damage a line without touching the cpc or the neutral so nothing will trip and there is no fault current. RCD for additional protection cant be used as you then cant comply with 314

Thanks Andy. So what would you do in that situation then install another fuse at about the 3 metre point or just change/upgrade the existing fuse at the service head?

 

[Andy™]

install the fuse as close to the meter as possible then tails to where ever they need to be. just be carseful its is DI tails as you wont be able to install them in a wall <50mm or anywhere thatll need additional protection by RCD, so you may need to use SWA or similar

 

[DaveS79]

install the fuse as close to the meter as possible then tails to where ever they need to be. just be carseful its is DI tails as you wont be able to install them in a wall <50mm or anywhere thatll need additional protection by RCD, so you may need to use SWA or similar

Cheers nice one good to know for the future

 

[Evans Electric]

I'd go with Andy ,    metalclad   60 / 80A Sw/fuse at the meter ,    16 sq mm SWA  to the  apartment  .  

 

[Sharpend]

But if this fuse that he speaks of is in a ryefield board which is after the suppliers cut out fuse is it necessary? 
also at what point Is the meter installed near too the cutout or is it local to the flat? 

 

[Andy™]

But if this fuse that he speaks of is in a ryefield board which is after the suppliers cut out fuse is it necessary? 
also at what point Is the meter installed near too the cutout or is it local to the flat? 

good point. a ryefield board would normally be owed by the BNO and not DNO so i guess it could be used. not really thought about it tbh

 

[Evans Electric]

Wouldn't a Ryfield board be before the meters   ?  If meters were in the apartments it wouldn't be within the contractor's remit to  be installing BEFORE   the meter. 

I'm still thinking  SWA  , surface to avoid the use of an RCD . 

 

[Sharpend]

Wouldn't a Ryfield board be before the meters   ?  If meters were in the apartments it wouldn't be within the contractor's remit to  be installing BEFORE   the meter. 

I'm still thinking  SWA  , surface to avoid the use of an RCD . 

 
In the circumstance a BNO set up allows the ryefield to be prior to the meter i do believe it is a necessary requirement, think 3ph incomes split to 1ph. 

 

[Sharpend]

I tried to edit my original post but I’m not allowed? 
 

so if you read this link for WPD it shows the requirement for an isolator/fuse switch/circuit breaker after the meter which is after the ryefield. 
https://www.westernpower.co.uk/downloads/3223

 

[Evans Electric]

Either option then . 

 

[DaveS79]

I tried to edit my original post but I’m not allowed? 
 

so if you read this link for WPD it shows the requirement for an isolator/fuse switch/circuit breaker after the meter which is after the ryefield. 
https://www.westernpower.co.uk/downloads/3223

Either option then . 

Sorry guys for the late clarification on my post and the confusion I caused with it . I couldn't initially see clearly the the cabling between ryfield, meter and apartment. On closer look it was just a supply to a ryfield board on 2nd floor and then from a 60amp bs1361 within ryfield to meter (which was within 3 metres) then 16mm armoured to apartment which is about 10metres. So as far as I can see it this was all fine and 18ed compliant? No need for fusing again of the armoured go in to apartment?

As for other posts thanks for clarification if ever in situation where meter tails do exceed the 3 metres

 

[Andy™]

Sorry guys for the late clarification on my post and the confusion I caused with it . I couldn't initially see clearly the the cabling between ryfield, meter and apartment. On closer look it was just a supply to a ryfield board on 2nd floor and then from a 60amp bs1361 within ryfield to meter (which was within 3 metres) then 16mm armoured to apartment which is about 10metres. So as far as I can see it this was all fine and 18ed compliant? No need for fusing again of the armoured go in to apartment?

As for other posts thanks for clarification if ever in situation where meter tails do exceed the 3 metres

depends who's fuse it is... down to DNO to see wether they will allow it to comply with 433.3.1(iii). if they say yes then all good, if they say no then itll need another fuse after the meter on the consumers side

 

[DaveS79]

depends who's fuse it is... down to DNO to see wether they will allow it to comply with 433.3.1(iii). if they say yes then all good, if they say no then itll need another fuse after the meter on the consumers side

 Cheers Andy

Is this what you would do in practice then....contact DNO and get some sort of documented response? Even in scenario like this where the only change of install is the board change. No expected load difference for install, no new circuits etc. The fuse rating for this cable was originally installed to serve purpose for supply to flats so nothing really has changed there

 

[Murdoch]

OP . 

What do your scheme technical line suggest?