Why oh why 25mm meter tails?

[sparc]

Does anyone understand the logic of 'mandating' 25mm meter tails when upgrading a CU, when the sizing of other cables are left to the electrician's discretion?

I'm again having to explain to a little old lady with not a lot of money that she's need new meter tails with with tiny 6-way board, for her tiny 2-bedroom flat.

Massively cooking range to feed? Nope! 10.8Kw Powershower? Nooooh!

When copper is becoming an increasingly rare resource shouldn't we be fitting what's needed?

My guess is that the IET are simply 10 years out of date, plus someone somewhere calculate the specification, then a sub committee adds 10% to that, and the main committee thinks - let's be in the safe side, and adds another 10%.

Craziness gone mad!!!

(Rant for the day over - thank you for listening)

 

[flukey]

I've been to quote on a couple of jobs in the last few weeks where the customer has been told "It must have an RCD" or "You need a new CU" when neither is true. I just can't make up my mind if it's an excess of greed, or a shortage of knowledge driving them to tell customers such things.

i take it your quoting for surface mount in trunking then?? perhaps others are chasing in properly??

 

[Tuttle]

well you can always replace tails but how about showing your assessor how you do diversity calcs...for current using equipment/connected loads as well as C/Us.....that would be good wouldn`t it....

Yeah, I suppose, as long as he is not of the opinion that tails should always be upgraded to 25mm.

For meter tails the OSG says: "the minimum cable size should be 25mm. The distributor may specify the maximum length and the minimum cross-sectional area". It doesn't say anything about sizing the tails according to the maximum demand. I'm not saying that you're wrong, I'm just saying that I think that I would have a hard time justifying why I ignored what it said in the OSG if it came up in an assessment.

 

[Tuttle]

The other thought I had was if the distributors tails between cut-out and meter are 16mm then perhaps I could assume that their minimum csa couldn't be any larger than 16mm.

 

[GLENNSPARK]

The other thought I had was if the distributors tails between cut-out and meter are 16mm then perhaps I could assume that their minimum csa couldn't be any larger than 16mm.

distributers tails are DNO property..so you wouldn`t worry about those anyway......unless they were damaged..then you pick up the phone.....

 

[jase]

distributers tails are DNO property..so you wouldn`t worry about those anyway......unless they were damaged..then you pick up the phone.....

and which tails are not their property then? the ones coming from the meter to the fuseboard? the meter you are not spose to touch cos that is also their property and it has a seal on it? so i essence we really shouldnt worry about changing any tails cos they are all sealed up and the DNO's :confused5:

 

[topquark]

and which tails are not their property then? the ones coming from the meter to the fuseboard? the meter you are not spose to touch cos that is also their property and it has a seal on it? so i essence we really shouldnt worry about changing any tails cos they are all sealed up and the DNO's :confused5:

Where the tails run from meter to CU/DB is not normally sealed, just a removable cover plate.

 

[flukey]

Where the tails run from meter to CU/DB is not normally sealed, just a removable cover plate.

with a seal on it lol

if meter is sealed and tails need changing this is where mr henley comes in

 

[Tuttle]

distributers tails are DNO property..so you wouldn`t worry about those anyway......unless they were damaged..then you pick up the phone.....

Ok, I know that, what I was trying to say was perhaps I could assume that the distributor's requirement for the csa of the tails on the consumers side of the meter would not exceed the csa of their own tails on their side of the meter, I just didn't explain myself very well. I'm guessing that the main fuse is probably only a 60A or 80A but I haven't checked yet.

Why do I feel like I am digging myself into a hole

 

[topquark]

with a seal on it lol

if meter is sealed and tails need changing this is where mr henley comes in

Not when I find them, not sure why that is.

 

[Tuttle]

When British Gas did some work around my house they sealed the Henley blocks as well!

For safety reasons I think as they are on the consumers side of the meter ... you'd have to be pretty daft to try and nick electric from there

 

[Geordie Spark]

I havent read all the posts!! but when I did my 16th edition and test and connect course years ago I was told that even though you may have a 60/80 Amp head at the time, the DNO may upgrade their service to 100 amp, therefore its prudent to fit 25mm tails.

I rewired my house recently - in fact, truth to tell, it's still ongoing - but I fitted 25mm tails from the new 15 way main switch + RCBO'd board to my isolator.

From the isolator back to the meter, & from the meter back to the cut out, the tails are the "old coloured" 16mm. Then the bloke came to change the meter not asked for by me, but sent by DNO and I handed him a nice new pair of tails & asked him to fit them in place of the old 16mm pair.

He refused, claiming it wasn't his job, so I now have what I think is the ludicrous situation of having 16mm "old coloured" tails from the cut out as far as the isolator, & then 25mm tails from the isolator to the CU.

The mind boggles !!!!

 

[Geordie Spark]

well you can always replace tails but how about showing your assessor how you do diversity calcs...for current using equipment/connected loads as well as C/Us.....that would be good wouldn`t it....

Show off !!!!! :lol:

 

[jase]

When British Gas did some work around my house they sealed the Henley blocks as well!

For safety reasons I think as they are on the consumers side of the meter ... you'd have to be pretty daft to try and nick electric from there

saftey reasons? you would still have to pull the cutout even to mess around on that side of the meter, and the cutout would be sealed!!!!

 

[1shortcircuit]

saftey reasons? you would still have to pull the cutout even to mess around on that side of the meter, and the cutout would be sealed!!!!

I never leave home without one???

 

[Tuttle]

saftey reasons? you would still have to pull the cutout even to mess around on that side of the meter, and the cutout would be sealed!!!!

Yeah, I think they just wanted to stop curious people from removing the lid and killing themselves, I thought that it was a bit strange, nothing to do with them really.

 

[UNG]

Where the tails run from meter to CU/DB is not normally sealed, just a removable cover plate.

with a seal on it lol

if meter is sealed and tails need changing this is where mr henley comes in

Some meters have a split terminal cover on the consumers side that is not sealed and has an isolator behind the cover so you can work dead occasionally some DNO's fit an isolator after the meter which has a split cover arrangement allowing access to the consumers side terminals only

Ok, I know that, what I was trying to say was perhaps I could assume that the distributor's requirement for the csa of the tails on the consumers side of the meter would not exceed the csa of their own tails on their side of the meter, I just didn't explain myself very well. I'm guessing that the main fuse is probably only a 60A or 80A but I haven't checked yet.

Why do I feel like I am digging myself into a hole

Years ago when you got the electricity board to connect tails after a rewire they would expect you to install 16 or 25mm² tails but the tails from the cut out to the meter where usually well undersized

I rewired my house recently - in fact, truth to tell, it's still ongoing - but I fitted 25mm tails from the new 15 way main switch + RCBO'd board to my isolator.

From the isolator back to the meter, & from the meter back to the cut out, the tails are the "old coloured" 16mm. Then the bloke came to change the meter not asked for by me, but sent by DNO and I handed him a nice new pair of tails & asked him to fit them in place of the old 16mm pair.

He refused, claiming it wasn't his job, so I now have what I think is the ludicrous situation of having 16mm "old coloured" tails from the cut out as far as the isolator, & then 25mm tails from the isolator to the CU.

The mind boggles !!!!

Last few meter changes I have seen done they changed the tails on the DNO side to 25mm² in the new colours

Yeah, I think they just wanted to stop curious people from removing the lid and killing themselves, I thought that it was a bit strange, nothing to do with them really.

Years ago the old electricity boards always sealed the henley blocks

 

[flukey]

Some meters have a split terminal cover on the consumers side that is not sealed and has an isolator behind the cover so you can work dead occasionally some DNO's fit an isolator after the meter which has a split cover arrangement allowing access to the consumers side terminals only

i have yet to come across a meter with an unsealed cover but sounds like a bloody good idea.


if isolators were fitted as standard then this thread wouldnt exist.

truth is, not many dno fit them so the choice is either install your own with 25mm tails on consumers side or henley them

 

[sparc]

with a seal on it lol

if meter is sealed and tails need changing this is where mr henley comes in

If the meter is sealed and the tails need changing then how does a henley block help? If there's one already installed between meter and CU, certainly. If not, you're going to have to open the meter to release the tails.

 

[flukey]

If the meter is sealed and the tails need changing then how does a henley block help? If there's one already installed between meter and CU, certainly. If not, you're going to have to open the meter to release the tails.

put meter tails into henley or isolator then into cu :dizzy2:

im all for cutting cutout seals but meter seals is a big no no

 

[1shortcircuit]

put meter tails into henley or isolator then into cu :dizzy2:

im all for cutting cutout seals but meter seals is a big no no

1 seal = Meter tail teminations other seal = ??? There's a reason I don't know the answer to the second. The reason I know the first is only because I read it on a public forum somewhere :thumbsup

 

[flukey]

1 seal = Meter tail teminations other seal = ??? There's a reason I don't know the answer to the second. The reason I know the first is only because I read it on a public forum somewhere :thumbsup

thats it youve lost me????????

 

[sparc]

put meter tails into henley or isolator then into cu :dizzy2:

im all for cutting cutout seals but meter seals is a big no no

Have to disagree with you there, flukey, or maybe I'm just not understanding you.

If this is about upgrading existing 16mm2 tails coming from the meter into CU then putting a Henley block in there isn't going to make them 25mm2 - You'll just have 16mm to service block, then 25mm from there to the CU. I don't think that's what the regs mean!

 

[jase]

yes sparc, but what flukey is doing by having 16mm out of meter to service block and then service block to CU in 25mm is leaving it so that the DNO can take the 25mm's straight into meter at a later date

 

[Edd]

I rewired my house recently - in fact, truth to tell, it's still ongoing - but I fitted 25mm tails from the new 15 way main switch + RCBO'd board to my isolator.

From the isolator back to the meter, & from the meter back to the cut out, the tails are the "old coloured" 16mm. Then the bloke came to change the meter not asked for by me, but sent by DNO and I handed him a nice new pair of tails & asked him to fit them in place of the old 16mm pair.

He refused, claiming it wasn't his job, so I now have what I think is the ludicrous situation of having 16mm "old coloured" tails from the cut out as far as the isolator, & then 25mm tails from the isolator to the CU.

The mind boggles !!!!

I think he may have been telling porky's, when I did a year of meter changing for the EEB (as it was at the time) we were told and given rolls of 25mm and Henley blocks and had to up the tails to 25mm if smaller was found... truth be told we were on price and I have to admit it we were changing them in minuits and the last thing we needed was to upgrade the tails!! maybe the DNO's policy has changed but we didnt change them not because it wasnt our job, but because we couldnt be bothered!!!



EDIT to say this was 20 years ago!! my morels have changed!

 

[1shortcircuit]

thats it youve lost me????????

Main cut out to meter and meter to consumer unit. Two seals on the meter one of which gives access to where the tails get terminated. The other seal I'm guessing gives you acces to the internals of the meter itself. I've never opened the other seals but Yes (Tin hat on) I have opened the seal to be able to terminate new 25mm tails from cut out to meter, meter to CU. If you leave 16mm before any 25mm tails then what's the point in altering anything?

 

[flukey]

Have to disagree with you there, flukey, or maybe I'm just not understanding you.

If this is about upgrading existing 16mm2 tails coming from the meter into CU then putting a Henley block in there isn't going to make them 25mm2 - You'll just have 16mm to service block, then 25mm from there to the CU. I don't think that's what the regs mean!

no problem with a bit of disagreement

YOU cant put 25mm tails into meter, but meter man can next time he comes

 

[sparc]

yes sparc, but what flukey is doing by having 16mm out of meter to service block and then service block to CU in 25mm is leaving it so that the DNO can take the 25mm's straight into meter at a later date

Thanks for clarifying, but it seems a pointless exercise if you ask me. I regard the meter tails as starting at the meter and ending at the distribution board. Electrically, having a bit of 25mm2 for the last segment doesn't change the overalll current carrying capacity of the tails, which are still limited to 87A by the 16mm segments. - IMHO.

 

[flukey]

Main cut out to meter and meter to consumer unit. Two seals on the meter one of which gives access to where the tails get terminated. The other seal I'm guessing gives you acces to the internals of the meter itself. I've never opened the other seals but Yes (Tin hat on) I have opened the seal to be able to terminate new 25mm tails from cut out to meter, meter to CU. If you leave 16mm before any 25mm tails then what's the point in altering anything?

shame on you tampering with dno equipment

 

[sparc]

no problem with a bit of disagreement

YOU cant put 25mm tails into meter, but meter man can next time he comes

Well, I'm thinking that the DNO / meter man won't - because that side of the meter isn't their They own everythin to and including the meter. They will say it's not their responsibility to upgrade it, but the customers.

 

[1shortcircuit]

YOU cant put 25mm tails into meter, but meter man can next time he comes

Legally - Correct

Physically - Incorrect

Put on new steel wire, non stamped seals. I wonder if any questions will be raised?

My meter had red temp seals on 6 years ago, that was before I replaced the consumer unit and had numerous meter readings done. Nothing was ever mentioned and the seals were never replaced for the steel wire type:thumbsup