Meter tails >3 metres in length

[andrew8902]

Hi

Has anybody ever found where this "rule has come from"? In the NAPIT codebreakers book it quotes "ESQCR regs" but it is not actually written in there. If it is a DNO rule then it comes under their regs (ESQCR), but as I said, it is not in there....

 

[Flanders]

I believe is DNO rules but not written in stone

 

[D Skelton]

It's not a regulation, nor a statutory requirement, don't worry about it. NAPIT can go swivel.

 

[DPG]

I think different DNOs sometimes have slightly different requirements, but the 3M rule is a good rule of thumb and should ensure compliance.

 

[D Skelton]

I think different DNOs sometimes have slightly different requirements, but the 3M rule is a good rule of thumb and should ensure compliance.

Compliance with what?

 

[DPG]

Compliance with what?

DNO requirements

 

[Ian1981]

It’s the DNO’s fuse for protecting their equipment, not for protection of the consumers side, other than what they allow which is typically 3 meters.
Not that they police it mind.
I also wouldn’t code it on an EICR tho for tails longer than this, provided that the fuse offered fault protection.

 

[D Skelton]

DNO requirements

It's important to remember that their 'requirements' are nothing more than 'nice to haves'. We have no legal or moral duty to comply with them.

I would take a far more case by case approach to the provision of isolation on tails rather than trying to stick religiously to a 3m preference expressed by companies who ultimately have no duristiction over anything past the main head.

 

[DPG]

It's important to remember that their 'requirements' are nothing more than 'nice to haves'. We have no legal or moral duty to comply with them.

I would take a far more case by case approach to the provision of isolation on tails rather than trying to stick religiously to a 3m preference expressed by companies who ultimately have no duristiction over anything past the main head.

I'm not saying you should necessarily stick to it 100%, I was saying it could be a rule of thumb guide to what DNOs sometimes require

 

[D Skelton]

I'm not saying you should necessarily stick to it 100%, I was saying it could be a rule of thumb guide to what DNOs sometimes require

I know you weren't. I was just making a general point.

 

[pc1966]

I think it comes from the regs 433.2.2 (ii) and 434.2.1 (i)

 

[Electrics]

What is the rule?

 

[D Skelton]

I think it comes from the regs 433.2.2 (ii) and 434.2.1 (i)

These regs may feed the rumour but are certainly nothing to do with DNO's asking for isolation within 3m.

Overcurrent protection for the tails will always be provided by the main fuse.

 

[andrew8902]

I believe is DNO rules but not written in stone

This is how it is written in the NAPIT Codebreakers book. If it is "ESQCR" then why is it not listed in there?? How can it be a DNO rule if different DNOs quote different lengths? Here in the westcountry, WPD will not allow sparks to remove the service fuse but in the east of the country the DNO permits it!

 

[Ian1981]

Why would you FI that?
What limitations during the inspection would lead you to believe that there could be potential for danger but a limitation on the inspection prevents you from finding out?
Then they quote the ESQCR ?

 

[7029 dave]

It’s the DNO’s fuse for protecting their equipment, not for protection of the consumers side, other than what they allow which is typically 3 meters.
Not that they police it mind.
I also wouldn’t code it on an EICR tho for tails longer than this, provided that the fuse offered fault protection.

Thats true about not being policed, with a lot of self connect meters/ isolators.I have seen a run well over 15meters tails+earth in copex.

 

[andrew8902]

These regs may feed the rumour but are certainly nothing to do with DNO's asking for isolation within 3m.

Overcurrent protection for the tails will always be provided by the main fuse.

16mm2 tails on a 100A fuse? Very common in Devon....And no, I don't mean the rating of the fuse carrier, I mean the actual fuse..

 

[Ian1981]

Unless your single dwelling electrical installation is pulling more than the 16mm tails (around 87 amps) then I don’t think there’s a particular issue.

 

[Aurai]

Morning All
433.2 Position of Devices for protection against overload.
I get this one as I try to get replacement Consumer Units at an accessible height, not tucked against the ceiling above kitchen cupboard etc. Latest one at skirting board height! Except where length does not exceed 3m a device must be provided. Various fused isolators available. Thank you

 

[D Skelton]

16mm2 tails on a 100A fuse? Very common in Devon....And no, I don't mean the rating of the fuse carrier, I mean the actual fuse..

Let me re-word it then; overcurrent protection for correctly sized tails will always be provided by the main fuse.

The point I was making is that within the context of 433 and 434 no other overcurrent protection is required.

 

[andrew8902]

Why would you FI that?
What limitations during the inspection would lead you to believe that there could be potential for danger but a limitation on the inspection prevents you from finding out?
Then they quote the ESQCR ?

I had an email from Western Power Distribution and they are saying that it is not written in ESQCR but it is a requiremnt of BS7671......What a joke.....

 

[Rockingit]

This is a common misinterpretation / debate around 433.2.2 (ii) and basically my view has always been that so long as the csa of the cables involved are ≥ In then there's no issue. I think the purist view is that you shouldn't for example have tails to a Henley and then split from there.

 

[Wilko]

Ha ha, you couldn’t make it up really. If its desired from an operational standpoint (for some reason ?) that should just be stated and Us Simple Folks likely will comply with their wishes. But to say it’s required from a tech perspective invites scrutiny and feedback, in my view.

From my limited knowledge, 2 tech related reasons for discussion :

- loop impedance may become too large and 5 seconds disconnection may be lost with the installed cutout fuse. This is an easy On Site Electrician calculation, perhaps?

- position of devices for protection against overload or fault with 3m of a reduction in conductors cross sectional area (Regs 433.2.2ii and 434.2.1 apply). If I use 25mm tails I often feel they are equal or bigger than the incoming DNO cable conductors anyway. Again an On Site Electrician observation perhaps?

 

[Rockingit]

If I use 25mm tails I often feel they are equal or bigger than the incoming DNO cable conductors anyway. Again an On Site Electrician observation perhaps?

Commonly 16mm Alu splitcon around here (WPD) but I think it literally depends half the time on what's on the van!

 

[Ian1981]

It’s the Blind leading the blind, it’s in the ESQCR, no it’s in BS7671.