Lighting protection of the TT system

[Sergeant]

In the TT system, we all know that the socket outlets must be protected by RCCB, RCBO or ELCB.
But for the lighting, is that necessary or forced that should be protected by RCBO?
Is MCB ok?

 

[RF Lighting]

I am not familiar with Chinese wiring conventions.

You would be better off asking in the electrics outside the UK forum, or maybe a chinese electrical forum if there is one.

 

[ericmark]

I do see where you are coming from. With a 6A MCB type B it needs 30A to flow to open the MCB using the magnetic part of the trip so the earth loop impedance needs to be better than 7.6 ohms and this could be achieved with an earth rod. However in the UK with a TT system the earth outside consumers installation is only required to be 21 ohm or less. So in the UK one does need a RCD on the lights.

You may find the earth loop impedance is better than 7.6 ohms but we can't guarantee it will stay that way. The DNO may allow their system to get to around the 21 ohm mark before doing any work to improve it.

 

[Sergeant]

I am not familiar with Chinese wiring conventions.

You would be better off asking in the electrics outside the UK forum, or maybe a chinese electrical forum if there is one.

That we design a project with British Standard outside CHN.

We also need to use the 17th.