Do tails HAVE to be upgraded?

[Robson689]

The blind leading the blind

I'm not blind, but maybe you could post the correct "maximum length" for metre tails. (After all, I only said I think the maximum is 3 metres as I was not sure.)

 

[Deleted member 9648]

I'm not blind, but maybe you could post the correct "maximum length" for metre tails. (After all, I only said I think the maximum is 3 metres as I was not sure.)

There is no maximum length in Bs 7671...but the DNO usually specify a maximum length without an isolator. This varies from 2.5m-5m....check with your DNO.
And it's got nothing to do with mechanical protection.

 

[Engineer54]

There is no maximum length in Bs 7671...but the DNO usually specify a maximum length without an isolator. This varies from 2.5m-5m....check with your DNO.
And it's got nothing to do with mechanical protection.

Isolator or switch fuse??

 

[londonlec]

The amount of time this has been dragging on I could have fitted the damn switch fuse myself and moved to the next job

 

[Deleted member 9648]

Isolator or switch fuse??

Yes correct, switchfuse....should have been specific.

 

[whazza22]

On further inspection, I found that the incoming tails are 16mm and the main earthing conductor is 6mm.

I am going to use the idea of installing a 60a switch fuse which will allow me to continue using the existing tails.

However, is 6mm not a bit small for the main earthing conductor, especially when I will bond gas and water with 10mm?

So my idea is to install a 60a switch fuse, upgrade the main earthing conductor to 10mm and leave existing tails. Then bond water and gas in 10mm. Thoughts?

 

[Geoffsd]

Depends on the installation and earthing method.

You will have to work out the necessary csa for earthing and bonding.

 

[electric will]

The blind leading the blind

Who said that?

 

[whazza22]

Depends on the installation and earthing method.

You will have to work out the necessary csa for earthing and bonding.

By adibiatic equation?

Those calculations always show a lot less than you would actually use.

Surely its acceptable to just upgrade main earth and bonding if 16mm tails are protected by 60a fuse

 

[Geoffsd]

Those calculations always show a lot less than you would actually use.

That could be because you actually use a lot more than you actually need.

Surely its acceptable to just upgrade main earth and bonding if 16mm tails are protected by 60a fuse

A lot would agree with you but I don't follow your logic.

 

[whazza22]

That could be because you actually use a lot more than you actually need.


A lot would agree with you but I don't follow your logic.

The reason for not wanting to replace the tails is that it will be a nightmare as the meter is in a communal hallway. Also the run is about 6 meters so will cost a fortune on cable.

 

[richy3333]

That could be because you actually use a lot more than you actually need.


A lot would agree with you but I don't follow your logic.

The reason for not wanting to replace the tails is that it will be a nightmare as the meter is in a communal hallway. Also the run is about 6 meters so will cost a fortune on cable.

But it's not you paying? I don't think cable of that length will cost a fortune, but how big is your fortune?

 

[whazza22]

But it's not you paying? I don't think cable of that length will cost a fortune, but how big is your fortune?

The person I'm doing it for does not want to fork out money if its not required. Times are tough.

It will cost approx £50 just for the cable.

25mm tails are £3 a meter and I need 6 metres of each + 16mm earth.

 

[richy3333]

The person I'm doing it for does not want to fork out money if its not required. Times are tough.

It will cost approx £50 just for the cable.

25mm tails are £3 a meter and I need 6 metres of each + 16mm earth.

I'm afraid these are the type of jobs I walk away from then. If a customer doesn't want it done properly. Pay cheap, pay twice.
At £3 per metre for tails, I'd change your wholesaler, and a 100m of 16mm earth is far less than £1 per metre

 

[telectrix]

16mm tails will happily carry 90A if ref. method C. even more if ref. F, although the osg does not quote a figure for this. if they show no signs of damage, leave 'em be. note on your cert. though that you recommend upgrading to 25mm.