Bonding Advice Needed

[Bolty2uk]

Hiya.
New to this great forum so firstly would like to say hi. Im not an electrician and dont confess to being technically minded but i do have a quandry so after some advice really.
Anyway. My question is this. In a building that has 5 seperate flats we have all incoming service heads at ground level then via a main switch and rcd a 16mm twin and earth goes to each flat where the sparky will fit new boards to serve each flat. Now as im a builder organising all this i need to make sure all the plumbing and electrics are in place before i start putting in dropped ceilings and studwork etc..

Now question is in each flat there will be metal pipes to heating and water etc and i would assume they need bonding.
Now. The sparks has told me he is happy to run 16mm earth to main incoming water and gas from main earth block where incomers all are near front downstairs. So in effect no extra bonding in each flat.
But another guy we use said we need to run 6mm earth from the earth block in the fuse board in each flat to all the metal stuff in that flat in addition to what first guy said.

Now to save a barney and me a job of having to rip up floorboards later on does anyone know who is right. My money is on second guy but the lad we always use is positive and its all getting a bit hassly lol.
Anyone have any thoughts.
Many thanks for and replies i might get.
Thanks

 

[westward10]

It would be acceptable to connect the main protective bonds at the service head if that is their intention.
To use T&E without earthed containment for a sub circuit to each flat so it requires additional rcd protection is quite frankly ridiculous as division of circuits is lost immediately.

 

[ipf]

Yep, it's all about taking correctly sized supply plus correctly sized earth to each flat, then the bonding for each.
Your lad's correct about one thing...he'll still have to bond at building entry point, too. They're all taken as separate installations.

A bit of a full design by the right person might be the way to go.

edit. Sorry lads, a bit late with that.

 

[Bolty2uk]

I wouldn't be too quick to knock the one man bands, some of us know what we are doing

Sorry Dave. Wasnt ment to come out like that. I truley appreciate your advice. Its clear you have a good understanding of this. It seems one or two things are wrong here and i need to find someone else. But my dilema is i dont know. And if i get another different answer im not sure who to go with.

 

[davesparks]

Sorry Dave. Wasnt ment to come out like that. I truley appreciate your advice. Its clear you have a good understanding of this. It seems one or two things are wrong here and i need to find someone else. But my dilema is i dont know. And if i get another different answer im not sure who to go with.

No worries.

Unfortunately the domestic market is flooded with less than competent electricians, particularly when it comes to designing an installation.

There's no hard and fast way to guarantee that the design you get is right, but you could look at paying to have the design work done as a separate job with full paperwork and specification provided for the installers to work to.

 

[Toneyz]

There are far too many electricians out there who would rather believe rumours and old wives tales or just haven't kept up with the current regulations.
The guy who wants to just install main bonding at the incoming positions is likely misunderstanding the regulations.
The guy who wants to install 6mm bonding is probably still applyjng the requirements of the 16th edition wiring regulations which were replaced by the 17th edition in 2008.

I agree with Dave when we used to do flats it depends upon the other services sometimes the gas would come from semi concealed gas meters externally into each flat and would bond where entry into flat but would treat each flat as a installation with 16mm earth to consumer unit then 10mm to services then treat landlords installation separate bonding to each services unless plastic pipe.

 

[Toneyz]

The lights will almost certainly need RCD protection, again this is something which changed in 2008 so there is no excuse for being out of date with the regulations.
But as you have worked out there should be multiple RCDs to minimise the amount of the installation which loses power when one trips.
The ideal option is to have each circuit protected by an RCBO, this is a device which combines the functions of an MCB and an RCD in to one unit. This keep every circuit completely separate.

Depending upon the installation methods the RCD/RCBO additional protection could be omitted .

 

[davesparks]

Depending upon the installation methods the RCD/RCBO additional protection could be omitted .

Which is why I said ALMOST certainly will require RCD protection.
It is unlikely that the lighting circuits in a domestic installation will not require RCD protection these days.

 

[Baker1988]

As it is just a small flat I presume there will only be 1 lighting circuit in each flat and as there will be a light in the bathroom that lighting circuit will need to be rcd protected in accordance with reg 701.411.3.3 of amendment 3 which states:
"In specific locations such as those containing a bath or shower
there is a requirement now to provide RCD protection on
all circuits, including the lighting and shower circuits." so lighting will also need rcd protection in my eyes

 

[Toneyz]

It was more the sub-distribution circuit that I was referring to ( however my preference is SWA) 16mm T & E with additional earth when run in compliance the need for a upfront RCD can be omitted ,which is against the regs anyway. I remember from when I started as a apprentice always installing two lighting circuits in flats and bungalows etc.

 

[Mikeluker]

Hiya.
New to this great forum so firstly would like to say hi. Im not an electrician and dont confess to being technically minded but i do have a quandry so after some advice really.
Anyway. My question is this. In a building that has 5 seperate flats we have all incoming service heads at ground level then via a main switch and rcd a 16mm twin and earth goes to each flat where the sparky will fit new boards to serve each flat. Now as im a builder organising all this i need to make sure all the plumbing and electrics are in place before i start putting in dropped ceilings and studwork etc..

Now question is in each flat there will be metal pipes to heating and water etc and i would assume they need bonding.
Now. The sparks has told me he is happy to run 16mm earth to main incoming water and gas from main earth block where incomers all are near front downstairs. So in effect no extra bonding in each flat.
But another guy we use said we need to run 6mm earth from the earth block in the fuse board in each flat to all the metal stuff in that flat in addition to what first guy said.

Now to save a barney and me a job of having to rip up floorboards later on does anyone know who is right. My money is on second guy but the lad we always use is positive and its all getting a bit hassly lol.
Anyone have any thoughts.
Many thanks for and replies i might get.
Thanks

The main bonding would only need to installed within the gas floor boxes outside on the consumer side of the stop cock. The main water assuming this would be in the riser position would require a main bond only in the incomer position both sized in accordance to the main neutral. They won't require any additional bonding within the flat themselves as there are no other earth potentials being introduced. The submains to the flats will require a disconnection time of 5 seconds so no rcd will be required. Each flat would need rcds / rcbos internally split across lighting circuits etc as not to cause full failure if a fault occurs.
Normally if an underground extraneous pipe goes from one building to another both bonds would be required as to equalise both potential differences between them, I hope this helps.

 

[Simonslimline]

Edited

 

[Simonslimline]

The main bonding would only need to installed within the gas floor boxes outside on the consumer side of the stop cock. The main water assuming this would be in the riser position would require a main bond only in the incomer position both sized in accordance to the main neutral. They won't require any additional bonding within the flat themselves as there are no other earth potentials being introduced. The submains to the flats will require a disconnection time of 5 seconds so no rcd will be required. Each flat would need rcds / rcbos internally split across lighting circuits etc as not to cause full failure if a fault occurs.
Normally if an underground extraneous pipe goes from one building to another both bonds would be required as to equalise both potential differences between them, I hope this helps.

So do you know the earthing arrangement regarding the incoming neutral comment????

It might not be PME!

Also I was not aware that a DT of 5 seconds makes a circuit void of any RCD protection!!!

 

[Toneyz]

So do you know the earthing arrangement regarding the incoming neutral comment????

It might not be PME!

Also I was not aware the a DT of 5 seconds makes a circuit void of any RCD protection!!!

It dosn't

 

[Simonslimline]

It dosn't

This I what I was pointing out. Could of worded it better though to be honest.

 

[Mikeluker]

So do you know the earthing arrangement regarding the incoming neutral comment????

It might not be PME!

Also I was not aware that a DT of 5 seconds makes a circuit void of any RCD protection!!!