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I'm doing a bathroom refurb this week. Today I inspected the existing install. The bathroom only has lighting circuit in it (6A mcb, no RCD protection).

The hot & cold services have supplementary bonding, as does the CH towel radiator. The non electric shower hot & cold service does not have supplementary bonding.

Tested continuity to all these pipes gives a reading of 0.04ohms to local cpc. Regulation 702.415.2, states all extraneous conductive parts shall be connected by supplementary bonding etc.......in accordance with reg 415.2. Using that formula (415.2) gives me a figure of 1.6ohms, less than my 0.04.

My thinking is that these pipes are effectively bonded elsewhere(supplementary, and I forgot to check the airing cupboard :oops:) and therefore the existing supplementary bonding does not require re-attaching. I only ask, as the shower has no visible supplementary bonding, and the towel radiator is being replaced, and the current one has a lovely EC clamp on the lowest bar?
 
I'm doing a bathroom refurb this week. Today I inspected the existing install. The bathroom only has lighting circuit in it (6A mcb, no RCD protection).

The hot & cold services have supplementary bonding, as does the CH towel radiator. The non electric shower hot & cold service does not have supplementary bonding.

Tested continuity to all these pipes gives a reading of 0.04ohms to local cpc. Regulation 702.415.2, states all extraneous conductive parts shall be connected by supplementary bonding etc.......in accordance with reg 415.2. Using that formula (415.2) gives me a figure of 1.6ohms, less than my 0.04.

My thinking is that these pipes are effectively bonded elsewhere(supplementary, and I forgot to check the airing cupboard :oops:) and therefore the existing supplementary bonding does not require re-attaching. I only ask, as the shower has no visible supplementary bonding, and the towel radiator is being replaced, and the current one has a lovely EC clamp on the lowest bar?
What figures are you using to get your 1.6 ohms Middy
 
50/30 =1.6
Assuming a 6amp type B mcb
I think that should be 50Volts/ Ia where Ia is the opperating current I delta n of the RCD which will be 50/.03 (30ma) which =1666ohms so anything over 1666 ohms is a lump of metal and less that 1666 ohms should require bonding, or as Chris Kitcher puts it
 
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I think that should be 50Volts/ Ia where Ia is the opperating current Ideltn of the RCD which will be 50/.03 (30ma) which =1666ohms
There’s no 30mA rcd,the lighting in the bathroom is protected by a 6amp mcb type B.
Hence 50volts/30 = 1.666 ohms
Ia in this instance is the minimum fault current to operate the OCPD which in this case is 30 amps.
In x 5 for type B mcbs.
 
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I'm doing a bathroom refurb this week. Today I inspected the existing install. The bathroom only has lighting circuit in it (6A mcb, no RCD protection).

The hot & cold services have supplementary bonding, as does the CH towel radiator. The non electric shower hot & cold service does not have supplementary bonding.

Tested continuity to all these pipes gives a reading of 0.04ohms to local cpc. Regulation 702.415.2, states all extraneous conductive parts shall be connected by supplementary bonding etc.......in accordance with reg 415.2. Using that formula (415.2) gives me a figure of 1.6ohms, less than my 0.04.

My thinking is that these pipes are effectively bonded elsewhere(supplementary, and I forgot to check the airing cupboard :oops:) and therefore the existing supplementary bonding does not require re-attaching. I only ask, as the shower has no visible supplementary bonding, and the towel radiator is being replaced, and the current one has a lovely EC clamp on the lowest bar?
i would imagine that if the hot and cold are supplementary bonded then as long as the pipes are continuous to the shower then they are effectively the same pipework.
 
There’s no 30mA rcd,the lighting in the bathroom is protected by a 6amp mcb type B.
Hence 50volts/30 = 1.666 ohms
Where does the 30 come from I'm having a brain fade
 
I think that should be 50Volts/ Ia where Ia is the opperating current I delta n of the RCD which will be 50/.03 (30ma) which =1666ohms so anything over 1666 ohms is a lump of metal and less that 1666 ohms should require bonding, or as Chris Kitcher puts it
Never considered using a IR test to work that out before... learn something every day..
 
Cant see the relevance....if you are altering/installing bathroom circuits you'll need to provide RCD protection which is likely to negate the need for SB.
He’s maybe just changing the centre light for all we know or maybe hes not?
 
Cant see the relevance....if you are altering/installing bathroom circuits you'll need to provide RCD protection which is likely to negate the need for SB.

Just replacing like for like luminaires.

If you can imagine, the rest of the refurb is fancy tiling, shower screens, furniture etc. Do I have to put that ec clamp on the bottom of their nice new chrome towel radiator?

Edit, oh and moving extract fan into loft space.
 
Just replacing like for like luminaires.

If you can imagine, the rest of the refurb is fancy tiling, shower screens, furniture etc. Do I have to put that ec clamp on the bottom of their nice new chrome towel radiator?

Edit, oh and moving extract fan into loft space.
Therefore if you are altering a circuit in a bathroom then RCD protection is required.
 
if you cant put a rcd in c/u put one outside the bathroom .
You could put one in front of the CU, would be easier than faffing with the bathroom circuits, I would think. Still think he is wrong to use the 30 Amps in his calculations. In the video CK is using 10ma as quoted in GN3 not a current that operates an RCD 230/.01 (10ma)= 2300ohms minus the resistance of the body ohms1000, in that calculation there is not any reference to the operating current of any OCPD, only referring to GN3.
 

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