Supplementary bonding scenario

[rainydays]

There are two circuits in a bathroom. One for the lighting and one for a combi boiler.

The lighting circuit has no cpc and the circuit is protected by an mcb 6 amp B type 60898.

The boiler circuit has a cpc and is protected by way of an 30 m/A RCD FCU.

Zs for this circuit is well within spec.

Main Protective equipotential bonding is in place for the gas and water.

No evidence of supplementary bonding however, the resistance between the cpc of the boiler circuit and all simultaneously accessible extraneous conductive parts is 0.15ohms. This resistance value is also the same between extraneous to extraneous.

The lighting circuit is not having any modifications, however the boiler is being upgraded.

All of the conditions for omitting supplementary bonding from the BRB are not being met so i am a bit confused on how to proceed with this one. Would i need to need to take a supplementary bond up to the luminaire and pull switch?

Observations and recommendations regarding the lack of a cpc will of course be raised and duly noted.

 

[sparkytim]

Is the light fitting class 2? if so then nothing to supplementary bond to, but boiler CPC should be supplementary bonded to ALL pipework, which it may be be means of the boiler pipe manifold

Would suggest RCD FCU or RCBO for lighting into bathroom as minimum to cover it

 

[Chr!s]

The supplementary bonding needs to be connected to all exposed and extraneous parts.

Some pipework/or similar may not be considered extraneous, though this will depend upon the resistance to earth.

 

[m4tty]

The supplementary bonding needs to be connected to all exposed and extraneous parts.Some pipework/or similar may not be considered extraneous, though this will depend upon the resistance to earth.

Is that a continuity test and if under 23k ohms then it's considered extrenous ?

 

[sparkytim]

Is that a continuity test and if under 23k ohms then it's considered extrenous ?

NOT extraneous if high reading.

BRB Pg 24 Extraneous-CONDUCTIVE -PART

 

[Chr!s]

Matty

Is that a continuity test and if under 23k then it's considered extrenous ?

Yes mate, presuming a bodily resistance of 1000 ohms add this to the 22k ohms for your 23 k ohms.

230 Volts divided by 23000 gives you 10 mA which is the let go threshold.

 

[rainydays]

Thanks for the replies. The light fitting is class 2 as is the pull switch.

My resistance values show that i am satisfying reg: 415.2.2 for the boiler circuit and 411.3.1.2 do they not.

My concern was with the lighting circuit as it had no cpc and no rcd protection