Supplementary bonding requirements

[rattlehead85]

Ok this has probably been covered before but still remains a grey area for a lot of sparks out there..

In a room containing a bath or shower reg 701.415.2 stipulates that local supplementary bonding shall be established connecting together the terminals of the protective conductor of each circuit supplying class I and class II equipment to the extraneous conductive parts of the location.
Now if conditions iv v and vi of 701.415.2 are not met do we A) provide additional supplementary bonding using green and yellow cable as described above.
or B) apply the equation of reg 415.2.2 first to determine if A) is needed.

Or is it that R<_ 50v/Ia is only supposed to be used to confirm the adequacy of existing bonding installed..

Tin hat at the ready[emoji21][emoji21][emoji21]

 

[Pete999]

Ok this has probably been covered before but still remains a grey area for a lot of sparks out there..

In a room containing a bath or shower reg 701.415.2 stipulates that local supplementary bonding shall be established connecting together the terminals of the protective conductor of each circuit supplying class I and class II equipment to the extraneous conductive parts of the location.
Now if conditions iv v and vi of 701.415.2 are not met do we A) provide additional supplementary bonding using green and yellow cable as described above.
or B) apply the equation of reg 415.2.2 first to determine if A) is needed.

Or is it that R<_ 50v/Ia is only supposed to be used to confirm the adequacy of existing bonding installed..

Tin hat at the ready[emoji21][emoji21][emoji21]

https://www.youtube.com/watch?v=v38PfIVy2rI

 

[rattlehead85]

I knew this would appear!! The question is though is it that the regs contained within section 701 specifically ask for supplementary bonding so therefore can we only use the equation to verify its adequacy if it is present??
This guys opinion differs from what the regs appear to detail.
If we carry out an inspection do we automatically attribute a C2 departure if there is no RCD or additional supplementary bonding present or do we apply the equation and if the results are satisfactory without the presence of additional bonding we just attribute a C3 for the lack of RCD to the circuitry within the location.??

 

[Richard Burns]

The equation in chapter 41 is only to check if the existing supplementary bonding is adequate.
I would say it should not generally be used to avoid applying supplementary bonding.
However if there is no supplementary bonding installed then the less than 50V touch voltage check may indicate that supplementary bonding is not needed as the resistance path back to the MET is low enough to ensure a "safe" touch voltage, (but supplementary bonding should make that touch voltage even lower). e.g. if the bathroom were next door to the consumer unit, extraneous parts are main bonded and the earth bar acts as the supplementary bonding link.

For a bathroom location section 7 specifies supplementary bonding is required (assuming the other conditions are not met) so it should be installed, though you may take the view that it is effectively installed by measuring the interconnected resistances. I would document this carefully though to cover yourself just in case.
It is normally easier to comply with the obvious requirements than to try and find a reason not to do so.

 

[rattlehead85]

The equation in chapter 41 is only to check if the existing supplementary bonding is adequate.
I would say it should not generally be used to avoid applying supplementary bonding.
However if there is no supplementary bonding installed then the less than 50V touch voltage check may indicate that supplementary bonding is not needed as the resistance path back to the MET is low enough to ensure a "safe" touch voltage, (but supplementary bonding should make that touch voltage even lower). e.g. if the bathroom were next door to the consumer unit, extraneous parts are main bonded and the earth bar acts as the supplementary bonding link.

For a bathroom location section 7 specifies supplementary bonding is required (assuming the other conditions are not met) so it should be installed, though you may take the view that it is effectively installed by measuring the interconnected resistances. I would document this carefully though to cover yourself just in case.
It is normally easier to comply with the obvious requirements than to try and find a reason not to do so.

Sensible advice and makes sense. So during an inspection the best way of coding it would be to carry out the tests to see if the pipework is actually extraneous then apply the formula. If the results comply but there is no evidence of actual bonding within the location then a C3 should be attributed for the lack of RCD and a separate C3 code for the fact that there is no actual sup bonding but results of the equation show touch voltages under fault conditions are sufficient.
If the results after applying the equation are insufficient then C2 codes for both the lack of RCD & Presence of effective sup bonding (even if there is green and yellow cables darting about in the location) should be attributed. Is that the correct procedure??

 

[Richard Burns]

Sounds pretty close, the actual codes are up to you on assessment of the danger level.
if there is no visual evidence of supplementary bonding but you think it there behind all that boxing in then test to apply the formula.
If there is supplementary bonding visible then test resistance between parts to see if it is continuous in the location.
I would tend to tighten up a connection if there were one part not continuous to save having to code, not strictly correct as you are just inspecting, but sometimes saves time.
If you have a bathroom with one class II light and light switch out of zones and non extraneous pipework then I would not code, if you have a shower, a heater, a towel rail and extraneous pipework then yes a C2.
I might also mention lack of accessibility to connections and lack of labelling if the supplementary bonding is there but not accessible.