supplementary bonding in bathroom
I'm renovating my bathroom at the moment and currently there is no
supplementary bonding. I have read several threads on uk diy, but I remain uncertain about some points. As I understand it All exposed metal work should be bonded together. This doesn't extend to things like loo roll holders etc. that are isolated. Provided the bonding is protected it can be done using 2.5mm cable. In my case all bonding is going to be carried out within the void under the bath or within a false wall I am having to build. This will be accessible, but only by unscrewing an access hatch or bath panel. I have a light fitted which has a metal case. This is mounted on the wall, but is fed from a junction box in the false wall. As the junction box is at the foot of the wall near to where the taps and radiators are bonded, can I simply connect these to the cpc at the junction box and avoid having a separate cable from the light down to the radiator. There is no need to actually link this bonding back to a cpc on the lighting or shower circuit. But because I have a shower and a light in the room these will be linked to the bonding anyway. Please confirm that I have got this right. Thanks, Tim |
supplementary bonding in bathroom
Provided the bonding is protected it can be done using 2.5mm cable.
Use 4mm. Providing protection is normally not practicable. I have a light fitted which has a metal case. This is mounted on the wall, but is fed from a junction box in the false wall. An adjacent junction box is an acceptable location for running the supplementary bonding. As the junction box is at the foot of the wall near to where the taps and radiators are bonded, can I simply connect these to the cpc at the junction box and avoid having a separate cable from the light down to the radiator. Personally, I would regard the junction box as too far from the light, so unacceptable unless the CPC was 4mm, which is VERY unlikely. However, it would be acceptable if the CPC was protected, such as being in a metallic conduit, and otherwise met supplementary bonding regulations for minimum size. There is no need to actually link this bonding back to a cpc on the lighting or shower circuit. There is if you have lighting or a shower. Christian. |
supplementary bonding in bathroom
Christian McArdle wrote:
Personally, I would regard the junction box as too far from the light, so unacceptable unless the CPC was 4mm, which is VERY unlikely. However, it would be acceptable if the CPC was protected, such as being in a metallic conduit, and otherwise met supplementary bonding regulations for minimum size. Provided that the run from the JB to the light is fairly direct and is in T&E cable I don't see why bonding to the CPC in the JB wouldn't be OK. A CPC in a sheathed cable is deemed to be protected for this purpose [see Regs. 547-03-01 to -03]. Bonding to the lighting circuit's CPC is not required if the light and any other accessories on the circuit (e.g. shaver point, fan) are outside the Zones. -- Andy |
supplementary bonding in bathroom
A CPC in a sheathed cable is deemed to be protected for this purpose [see
Regs. 547-03-01 to -03]. Ah. I had missed that one. I had thought that protected had the same meaning as for buried cable runs. That's useful to know. Christian. |
supplementary bonding in bathroom
On Thu, 24 Aug 2006 13:07:33 +0100, Andy Wade wrote:
Christian McArdle wrote: Personally, I would regard the junction box as too far from the light, so unacceptable unless the CPC was 4mm, which is VERY unlikely. However, it would be acceptable if the CPC was protected, such as being in a metallic conduit, and otherwise met supplementary bonding regulations for minimum size. Provided that the run from the JB to the light is fairly direct and is in T&E cable I don't see why bonding to the CPC in the JB wouldn't be OK. A CPC in a sheathed cable is deemed to be protected for this purpose [see Regs. 547-03-01 to -03]. Bonding to the lighting circuit's CPC is not required if the light and any other accessories on the circuit (e.g. shaver point, fan) are outside the Zones. ....or are Class II equipment? -- Ed Sirett - Property maintainer and registered gas fitter. The FAQ for uk.diy is at http://www.diyfaq.org.uk Gas fitting FAQ http://www.makewrite.demon.co.uk/GasFitting.html Sealed CH FAQ http://www.makewrite.demon.co.uk/SealedCH.html Choosing a Boiler FAQ http://www.makewrite.demon.co.uk/BoilerChoice.html Gas Fitting Standards Docs he http://www.makewrite.demon.co.uk/GasFittingStandards |
supplementary bonding in bathroom
wrote in message
ups.com... ===Clip Provided the bonding is protected it can be done using 2.5mm cable. In my case all bonding is going to be carried out within the void under the bath or within a false wall I am having to build. This will be accessible, but only by unscrewing an access hatch or bath panel. Hmm - OK I'm Confused... and on re reading the regs I'm still confused.. I expected one of the Gurus to chip in that 4mm was needed not 2.5mm. I had thought that 4mm cable in a nice green/yellow cover running round the bathroom was the way to go.. In sections 547-03-02 & 03 what is the meaning of "sheath" and "mechanical protection".. These don't get spelled out in the definitions. Is "Sheath" the green/yellow plastic stuff? What is "mechanical protection" in this context? The side of a bath? Steel conduit? And why should the type of protection dramatically affect the diameter of the bonding... Hmm - I'm obviously confused - could somone please spell out 547-03-02 & 03 in simple terms! Many thanks, Roy |
supplementary bonding in bathroom
Ed Sirett wrote:
Bonding to the lighting circuit's CPC is not required if the light and any other accessories on the circuit (e.g. shaver point, fan) are outside the Zones. ...or are Class II equipment? No, the CPCs of circuits feeding equipment within the Zones should be bonded, even if all such equipment is Class 2. That was one of the significant changes made when the new bathroom rules were introduced in 2000. I've always assumed it's so that the bonding is already in place for when replacement Class 1 fittings get installed. -- Andy |
supplementary bonding in bathroom
RzB wrote:
Hmm - OK I'm Confused... and on re reading the regs I'm still confused.. I expected one of the Gurus to chip in that 4mm was needed not 2.5mm. I had thought that 4mm cable in a nice green/yellow cover running round the bathroom was the way to go.. It is, usually. You "can't go wrong" if you use 4. In sections 547-03-02 & 03 what is the meaning of "sheath" and "mechanical protection".. These don't get spelled out in the definitions. Is "Sheath" the green/yellow plastic stuff? No, that's insulation. All separate protective conductors of 6 mm^2 or less have to be insulated [543-03-02]. Sheath is a second layer of PVC, usually grey, like the outer of twin-and-earth cable or meter tails. What is "mechanical protection" in this context? The side of a bath? Steel conduit? And why should the type of protection dramatically affect the diameter of the bonding... I've always assumed it to mean "enclosed in some recognised form of wiring system" - i.e. conduit (steel or PVC) or trunking (including mini-trunking). The intent of the regs is to prevent separate thin easily-broken wires being used. IOW 4 mm^2 is considered sufficiently robust not to get damaged, even if not enclosed. Hmm - I'm obviously confused - could somone please spell out 547-03-02 & 03 in simple terms! 547-03-02: For electrical purposes the size of bonding between electrical circuit earths (CPCs of e.g. shower and lighting circuits) and extraneous-conductive-parts (e.g. heating pipes) must be at least half the size of the relevant CPC, but subject to a minimum of 4 mm^2 for reasons of mechanical robustness if not enclosed. 547-03-03: Same thing, but between two extraneous-conductive-parts. Electrical: 2.5 min, but 4 if not enclosed. There is another constraint in 413-02-28 which imposes resistance limits for supplementary bonding. In principle this could mandate larger sizes than 547-03-xx, - but not in a normal-size bathroom. HTH -- Andy |
supplementary bonding in bathroom
Andy,
Ahh - all a little clearer now. I'll stick to 4mm and all will be well... :-) Thanks for your excellent response, Roy |
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