New CCU in TT installation - bonding question

[Stormflex]

I will be fitting a new CCU in a house that has a TT installation. Going to look at the job tomorrow evening but just been doing a bit of reading up so I know what to check for - particularly as the homeowner mentioned he was a bit unsure about the bonding.

I'm pretty sure it will have an earth conductor and I'm really hoping all the main bonding conductors are satisfactory. From what I've read I suspect, what he might mean is, that the supplementary bonding is missing.

My understanding is that this is acceptable if all final circuits in the installation are protected by RCD/s and the maximum disconnection times are satisfied and...

"All extraneous-conductive-parts of the location are effectively connected to the protective equipotential bonding according to Regulation 411.3.1.2"

Just so I'm clear, does this last bit mean that if there is "main bonding" to the water installation pipes and the central heating system (those items most likely found in the bathroom) then supplementary bonding is not required?

Anything else unusual I should be looking for whilst I'm there?

Cheers for your help

Rich

 

[telectrix]

think you just about got it sussed mate. looks good to me.

 

[nick611]

central heating dosent need bonding,unless it comes in from outside.

 

[Stormflex]

Thanks for the confirmation telectrix

Can I just check as well regarding the RCDs --> Split load CCU, 1x 100mA, 1x 30mA

On the 30mA - socket outlets and "locations containing a bath or shower". What am I looking for in the bathroom? Shaver points? Electric heaters? (I assume the ceiling lighting isn't included in this).

Everything else on the 100mA.

 

[Stormflex]

Cheers nick611. So basically I just need to check that there's main bonding to the water and gas service pipes.

 

[telectrix]

Thanks for the confirmation telectrix

Can I just check as well regarding the RCDs --> Split load CCU, 1x 100mA, 1x 30mA

On the 30mA - socket outlets and "locations containing a bath or shower". What am I looking for in the bathroom? Shaver points? Electric heaters? (I assume the ceiling lighting isn't included in this).

Everything else on the 100mA.

nope. both RCDs need to be 30mA

 

[nick611]

100ma dosent cover cables in walls,socket outlets or any circuit in bathroom,its 30ma on everthing now.

 

[yellowvanman]

You need to have 30mA RCDs on all circuits if the cables are concealed in the wall, so you need a 17th Edition split CCO with 2 x 30mA RCDs

 

[telectrix]

every circuit has to have 30mA protection , anything, including lights, in a bathroom, any circuit with cables buried in walls less than 50mmm deep, every socket, even the cat flap and the bog seat, if they're electric.

 

[telectrix]

wylex 10 way 17th split board loaded with 8MCBs, £65+vat, electric center

 

[nick611]

check the stake as well,make sure its protected at the connection and labelled and below 200ohms.

 

[Stormflex]

OK, got it. I'd read the bit in the OSG about TT earthed steel conduit installations. Now I don't know that this house has that but I guess I can check in a couple of sockets to see if there is any conduit running to them. Make life easier if there isn't!