spare fuseboard

[Mephisto]

Hi all. I will do some ring, lighting, smoke alarms on the new loft for my client. I haven't space in the old fuseboard, so I thought to install a second small fuseboard. Should I connect earthing cable to the pipe? Thanks for any help.

 

[timhoward]

What is the pipe, and where is it?

 

[Mephisto]

What is the pipe, and where is it?

I mean the water pipe. It's the same location as the fuseboard 40cm from the fuseboard.

 

[westward10]

I mean the water pipe. It's the same location as the fuseboard 40cm from the fuseboard.

You mean earth the new board from the water pipe or its main protective bond.

 

[Mephisto]

You mean earth the new board from the water pipe or its main protective bond.

Yes, main protective bond. Sorry to write not clearly.

 

[timhoward]

For avoidance of doubt -
Is the question that there is a water pipe close to where you want to put the new board, and do you have to bond it to the new board?

 

[Mephisto]

For avoidance of doubt -
Is the question that there is a water pipe close to where you want to put the new board, and do you have to bond it to the new board?

I mean, do I have to bond it? The space between the water pipe and fuseboard is correct.

 

[westward10]

I mean, do I have to bond it? The space between the water pipe and fuseboard is correct.

It isn't really clear what you are asking.

 

[Dartlec]

If the pipe is already suitably bonded to the existing board, then you don't need to bond it again from the new board.

If you're splitting tails in a henley block or similar then adding an earth bar with suitable earthing cable to the new board might be a handy place to put the main bonding in for future ease of testing/identification.

But if the existing board is the MET then also fine to just run suitable earth to the new board from there if there is space.

If the existing bonding is 6mm then now would be a good chance to upgrade it to 10mm

 

[timhoward]

@Dartlec beat me to it.

I would say "No, you don't need to bond it".
My reasoning is:
The water pipe should be bonded at the point of entry to the building anyway (assuming it isn't plastic where it enters). So main protective bonding requirement should be already fulfilled. If you want to be sure you could continuity test the pipe with a wander lead to the MET.
Unless the new board is in a bathroom or other 'special location' there isn't a requirement for supplementary bonding either.
So I can't see a good reason to bond it again.

(It was once the case to say "If in doubt, bond it". Some still say this. But I don't think this is a good answer as by following this mantra things can become live in fault conditions that otherwise wouldn't.)

 

[IAmSparkytus!]

But if the existing board is the MET then also fine to just run suitable earth to the new board from there if there is space.

I was taught never to earth a board from another board and to split the earths in a Lucy block or other suitable accessory.

Never questioned it but now I am. Is it fine to take an earth from an existing board?

 

[telectrix]

One earth - Live it

 

[pc1966]

I was taught never to earth a board from another board and to split the earths in a Lucy block or other suitable accessory.

Never questioned it but now I am. Is it fine to take an earth from an existing board?

I don't see any reason why not so long as there are enough free terminals able to take the (probably) 16mm conductors. After all if you took a sub-main then it comes from there.

However, I also think it is good practice to have the MET separate from the CU so it is clear for inspection and test where the DNO earth and extraneous bonding goes, and in that case you would simply take each board's earth from the MET block.

Which is what you already do and, I believe, the best way.

 

[pc1966]

(It was once the case to say "If in doubt, bond it". Some still say this. But I don't think this is a good answer as by following this mantra things can become live in fault conditions that otherwise wouldn't.)

I would still suggest that for anything that:

• Could introduce a potential by means of it carrying cables, or being somehow in contact with the Earth (below 20k ohm) so "extraneous"
• Can be touched when also in contact with anything else on the CPC circuit

For example, I would not bond radiators as the pipe work should already be bonded and then they can't introduce anything else, but I would bond cable tray carrying any sort of power cable.

 

[IAmSparkytus!]

but I would bond cable tray carrying any sort of power cable.

Are you bonding cable tray as it's an exposed conductive part and it can become live under fault conditions? In this case the fault would have to be a damaged cable I'm presuming?

 

[pc1966]

Are you bonding cable tray as it's an exposed conductive part and it can become live under fault conditions? In this case the fault would have to be a damaged cable I'm presuming?

Yes. It is quite conceivable for a cable to get damaged on the edge of tray and make contact.

 

[IAmSparkytus!]

Ive watched a video on the eFixx YouTube about this before and his opinion was that if the cable could introduce a fault which made the cable tray live, this would suggest the cable or containment is unfit for purpose.

Cant see the logic in this personally as surely that would mean only SWA could be installed on tray so the armouring became live rather than the tray if there was a fault?