Running Main Bonding Externally

[walec]

Hello All,

Been asked to change some bathroom lights and other jobs at an old house recently but preliminary inspection shows there is no main bonding in the property. Unfortunately the incoming gas is one side of the house and the water the other, both in the middle and the CU and meter at the front of the house (PME), there is no way of running one cable between the two and no way of running the cable internally (without making a hell of a mess) so the only option is to run externally. I want to mechanically protect the 10mm cable but 20mm conduit seems a bit of an overkill, so I am asking for any help/ideas on mechanical protection, its a 20M run either side of the house and I will even have to go up and around a porch as well! Customer has also said they want black as the guttering is black so I dont see many options. Thanks

 

[Amp David]

I think that conduit is the only way to make it look neat and tidy really

 

[pushrod]

This feels so wrong, so it probably is, but just thinking out of the box for a minute would it be wrong to run the bonding in something like 3 core 4mm black butyl flex and just sleeve all the cores in G/Y at the ends. Any comments like "don't be so stupid what about reg ***" gratefully received

 

[telectrix]

or you could use 1/2" ali tube same as alrm engineers use for external cable protection. can paint black as well.

 

[J@mes]

This feels so wrong, so it probably is, but just thinking out of the box for a minute would it be wrong to run the bonding in something like 3 core 4mm black butyl flex and just sleeve all the cores in G/Y at the ends. Any comments like "don't be so stupid what about reg ***" gratefully received

Just what I was thinking - why not use SWA and sleeve the cores?

 

[mechelec]

why the mechanical protection? I have to say I have run it externally on more than one occasion. You could run into 10mm with a car and it would not be damaged (well the core would be intact)

 

[telectrix]

client wants it black, painting over green/yellow defeats the object. would then look like coax and might be inadverently cut

 

[Izzy's Dad]

Customer has also said they want black as the guttering is black so I dont see many options

So use black conduit!

 

[Amp David]

Dodn't bodge it do it properly, conduit all the way!

 

[mechelec]

missed the black bit in your first post. Black conduit then.

 

[AlanWirral]

Yep i've used black conduit myself and actually looked good.

 

[robsparky1975]

As far as i am aware if its not on the side of the house where there is a public walkway(i did one all in conduit) it does look more neat,how many t+e cables have we all seen clipped around houses,even more untidy,i think if its left either end 100mm or so to show its an earth cable there might not be a problem,think there is a reg which will clarify,dont have brb to hand.

 

[AlanWirral]

Arrrr actually Rob that rings a bell mate! We had to leave one end showing 100mm to show what it was. Can't remember exactly the amount..

 

[lamb]

You could run a black 10mm singles clipped direct or p-clipped, this would not contravene any regs if it was correctly identified at it's terminations (green/yellow). The regs recommend it to be G/Y throughout its length but this requirement is not absolute.
If clipped direct I would recommend Tower 5mm Pin Plugs and 6mm round black clips to get a good fixing in hard brick or render.

 

[empress]

You could run a black 10mm singles clipped direct or p-clipped, this would not contravene any regs if it was correctly identified at it's terminations (green/yellow). The regs recommend it to be G/Y throughout its length but this requirement is not absolute.
If clipped direct I would recommend Tower 5mm Pin Plugs and 6mm round black clips to get a good fixing in hard brick or render.

sounds like the cheapest most sensible option.
not big on the 20mm conduit option would look crap in my eyes.
as for protection had an inspection the other week elecsa .
main bond on the job had been done previously by gas board when new boiler was fitted tncs 10mm earth.
same prob so they clipped external round the house under the low level bell of the render.
i raised the question & the inspector had no problem with it.

 

[Benny2]

because the earth cable is mechanicly protected you can drop it down to a 2.5mm cable cant you lads?

 

[empress]

because the earth cable is mechanicly protected you can drop it down to a 2.5mm cable cant you lads?

think the origional post stated pme supply

 

[robsparky1975]

because the earth cable is mechanicly protected you can drop it down to a 2.5mm cable cant you lads?

I think you might be thinking of a tt supply main earhing conductor,main earth bonding to gas/water on a pme supply would be 10mm2 even if it had extra protection.

 

[pushrod]

Hasn't the resistance of a main bond got to be 0.05ohms or less? If that is the case OP could be struggling running it around the house because you only have 27 metres before you would have to increase the csa!

 

[Benny2]

That will be it robsparky just something that stuck in my head from my 2391, i dont come across pme much glad i hav recapped now thanks.