rcd tails

[paul b b]

Hello all,

customer may want meter moved making the tails more than 3m, so will need rcd protection, i have never done this and would like to (or sound like) i know what i'm talking about when it happens.

what rcd do you use? are both L & N to have a rcd?

many thanks.

paul

 

[NozSpark]

Normally tails in excess of 3m (so long as they are not <50mm) need protection by a switch fuse.

If you have to burry them then you should think about using SWA..

That is assuming its TN and not TT

 

[kme]

Hello all,customer may want meter moved making the tails more than 3m, so will need rcd protection, i have never done this and would like to (or sound like) i know what i'm talking about when it happens.

OK. The length of the tails has no bearing on RCD requirement. You WILL need local isolation - but not necessarily RCD

what rcd do you use? are both L & N to have a rcd?

many thanks.

paul

I find the second part of that question scary! Can you explain how / where you can have an RCD that only covers ONE of these?????

KME

 

[Evans Electric]

Hi Paul , you don't really want an RCD on your meter tails . Run them in some trunking . You will,though, need to fit a switchfuse to tails over 2m long. There is a domestic 80 A sw/fuse about

 

[NozSpark]

That'd be the 800KMF... great little switch fuse for this kind of thing!

 

[spinlondon]

3m is what is stated in the Regulations.

Individual DNOs may have other requirements.

 

[PC Electrics]

3m is what is stated in the Regulations.Individual DNOs may have other requirements.

Please, state the regulation number.

 

[paul b b]

OK. The length of the tails has no bearing on RCD requirement. You WILL need local isolation - but not necessarily RCD I find the second part of that question scary! Can you explain how / where you can have an RCD that only covers ONE of these?????

KME

errr yeah sorry KME, it's been a long day put the kettle on.... i was thinking that both has its own rcd thus could cause a problem if just the N tripped. but ofcause not....

 

[spinlondon]

There are two regulations that refer to this, one relates to Overload protection, and the other to Fault protection.

Both state that the device or devices can be along the run of a conductor, but whithin 3m of any change in current-carrying capacity.

433.2.2 refers to Overload, and 434.2.1 refers to Fault protection

 

[paul b b]

Hi Paul , you don't really want an RCD on your meter tails . Run them in some trunking . You will,though, need to fit a switchfuse to tails over 2m long. There is a domestic 80 A sw/fuse about

 

[NozSpark]

800KMF would be OK so long as -

a) it's a TN installation

B) the tails are not burried <50mm

 

[paul b b]

ok thanks noz, and if they are burried?

 

[NozSpark]

ok thanks noz, and if they are burried?

Then they either need RCD or mechanical protection (ie. SWA, MICC etc)