Where to insert RCD protection on circuit?

[williaminsurrey]

Hi - The circuit supplying my water heater also supplies two indoor sockets. The circuit, illustrated below, is on the non-RCD side of my split-load CU, and is protected by a 16A MCB.

CU-----Water Heater-----SKT-----SKT

The current set-up isn't ideal, and I want to provide RCD protection to the two sockets. Where's the best place to install the RCD?

1). Install 16A RCBO at the CU
2). Install 13A RCD FCU between water heater and first socket
3). Another arrangement?

Cheers for any help.

 

[securespark]

Fit a stand-alone after the water heater and before the first socket.

Make sure it is 30mA & at least rated to the circuit device.

You could fit an RCD spur, but then your total load on the 2 outlets c
ould only be a maximum of 13a.

 

[Adam_151]

There shouldn't really be sockets on the water heater circuit, is it possible to remove the sockets onto a fing final circuit, perhaps by using an FCU?

 

[securespark]

Point taken Adam.

The worst that could happen is nuisance tripping of the MCB if 16A is exceeded for any length of time.

BTW, I spoke to the NIC helpline not long ago. They do not recognise the OSG at all. They work purely from the regs book.

In that case, I revise my advice. If the two sockets can be limited to 13A between them, fit the RCD fused spur as you suggested.

Then the chances of nuisance tripping are very much lessened.

If you could sever the connection with the WH and feed the sockets from the ring final, that would, in my mind, be best.