Bit of help please.

[Evans Electric]

This has cropped up yet again , I've had a scan of the BRB etc. but as I thought , there is no mention of it.

On a large extension out in the sticks , EON are re-routing the overheads to our new meter c/bd (TT) Customer is dealing with them , and left a message with the builder that I will should fit a Sw/fuse for the meter tails , which will be about 8 mtrs long.

The way I have always dealt with this situation is to demand they leave an isolator after the meter and the consumer's tails are protected by the service fuse .

The fuse business crops up from time to time but I can't see the point of having two 100A fuses downstream .

So , is there anything carved in stone ' cos if it is , I don't know where it is.

 

[Sidewinder]

ESQCR or, DNO requirements Deke, don't think you'll find it in 7671 buddy.

I'd have to check ESQCR, but it is available FOC on the net as well as a few guidance notes.

Thing is you need to comply with DNO before the CU as I understand it, ESQCR derived.

 

[Barx]

No regs as far as I'm aware. It's just what DNO stipulate. And, although many will be fine with just an isolator. Alot say 3m Max. for tails. Therefore only way round it is to install a sub-main (with switch fuse). At the end of the day, they could say whatever they want and if you dont comply they simple refuse to energise.

 

[steptoe]

AFAIAA the DNO fuse is not for protection of the customers tails, it is to prevent the customer overloading the DNO cable, so that is the point where you need to provide the protection for the tails comes in.

 

[Andy™]

as per 7671, all your installation needs adequate protection. the service fuse is not yours, so you have to provide your own. however, they will let you use the service fuse for short tails (& high PFC backup)

 

[Phoenix]

BS7671 (will dig out reg no. later if needed) allows you to rely on overcurrent protection of supply authority equipment only with permission of the supply authority, which is generally what applies in the case of tails. However most supply authorities have conditions to this permission and will only grant it if for example tails are under 3m (the reason is simple, if they were to say "yes, use our cutout fuse to protect your tails" unconditionally they would have to then be sure that their fuse is appropiate.. i.e. zs in spec for fuse fitted, they cannot possibly do that if the tail length is undefined... so they design their part for example so that the zs will be in spec with upto 3m [or whatever they specify in your case] in all instances and make tail length a rule for all installs, its a bounds of responsibly thing)

There is no particular need to ensure discrimination between your switchfuse and the cut out fuse though

 

[Chr!s]

AFAIAA the DNO fuse is not for protection of the customers tails, it is to prevent the customer overloading the DNO cable, so that is the point where you need to provide the protection for the tails comes in.

Id have to disagree there steps, ESQCR requires all equipment installed within the installation to comply with BS7671, so that will include protection to the meter tails.

 

[Evans Electric]

Thanks guys , in Brum there seemed to be an unwritten rule of 2m-3m for tails . This comes under Evesham I think, but I'll remove their DP switch and fit a fuse, (ass is covered then) its not such a big deal now there is one for

 

[steptoe]

Id have to disagree there steps, ESQCR requires all equipment installed within the installation to comply with BS7671, so that will include protection to the meter tails.

I dont understand how that is in disagreement to what I said,

the DNO fuse is to protect their equipment, the tails on CU side of the meter are yours so you need to provide protection for them.

as a point to your post, I dont agree that everything within the installation has to comply with 7671,

DNO flaunt 7671 on a regular basis, so IMHO it only applies to the consumers side,

I may well be totally wrong on all of this, its just how I understand the situation.

 

[Chr!s]

I dont understand how that is in disagreement to what I said,the DNO fuse is to protect their equipment, the tails on CU side of the meter are yours so you need to provide protection for them.

as a point to your post, I dont agree that everything within the installation has to comply with 7671,

DNO flaunt 7671 on a regular basis, so IMHO it only applies to the consumers side,

I may well be totally wrong on all of this, its just how I understand the situation.

Sorry misread

ESQCR Guidance

Equipment belonging to distributors and meter operators which is installed on consumers

 

[steptoe]

No worries Chris,

I thought I had maybe got a misunderstanding of it somehow.

 

[mikep]

Yep went through this and did this to keep everyone happy just look at that big boy I put in.

Mike.

http://www.talk.electricianforum.co.uk/attachments/question-answer-board/933d1279907226-new-build-15072010446.jpg

 

[kerching]

Was it not called something like 'CM16 Conditional rating' or some such thing? NO idea where I dragged that one up from but it is ringing bells somewhere way way way back in the v.old grey matter! ... :coat

 

[steptoe]

Yep went through this and did this to keep everyone happy just look at that big boy I put in.Mike.

http://www.talk.electricianforum.co.uk/attachments/question-answer-board/933d1279907226-new-build-15072010446.jpg

is that isolator locked in the on position????????

NOT good, :|

 

[wozz]

looks like its pointing at the 0 to me so in the off position.

Evans would need a insulated one as its a TT system.

 

[steptoe]

looks like its pointing at the 0 to me so in the off position. Evans would need a insulated one as its a TT system.

youre right,

my bad, just looking at colours,

thats another thing,

why dont we have standard colours for on and off?

does my head in, some makes are green for on/go, some green for safe.

 

[Sidewinder]

Steps,

It depends on the age and in some circumstances the industry of the equipment!

There are now global and accepted standards but they take time to implement.

 

[apprentice87]

Hi all, Firstly, Steptoe is right in all of this, the DNO cutout is to protect THEIR equipment and NOT yours and also, regulations certainly do apply!

The DNO are, as Steptoe points out, seemingly exempt from BS7671. They can for example, have cables with combined PE and Neutral, [as in CNE service cables] This is specifically prohibited by BS7671 in a consumers installation, but the DNO can have them!! So some, or, I would not be surprised, perhaps all of BS7671, does not apply to them.

Anyway, back to the problem! In general, the DNO will not let you have tails more than 3 meters long without overcurrent protection for them. They probably do not know why themselves, but their attitude will be

 

[a1]

 

[apprentice87]

How do i make photos smaller?? as everytime i try to email a photo or post them on anything they are too big! How do i shrink file sizes?? Should i try to sign up for one of them "photo hosting" things? i could put a few on there??

john.