supplementary bonding ???

[loopy]

Hi ,,, weve got lots of different opinons of this on a large particular job at the moment but would like a view of others in the know ,,,, heres the question, the job started in 2007 and designed to 16th edition.... once the 17th edition started they started to omit the supplementary bonding ... is this ok

this is the schedule..12 way board - 1 30ma rcd--- Main ex bonding 10mm2- 25mm2 tails 16mm2 main earth

Non Rcd Side
1. lights general b6 inc bathroom + shaver
2. lights kitchen
3. central heating
4. smokes
RCD 30Ma --------------------------------------------------------------
5. sockets ring 1
6. Sockets ring 2
7. underfloorheating (within bathroom) (supp bonding omitted)
8. towel rail (within bathroom) (supp bonding omitted)

noted that the lights within the bathroom plus shaver point not protected by 30ma rcd ... please help

 

[saveloy]

I think it is probably pushing it a bit to sign this job off now under 16th edition regs!! You cant omit supplementary bonding as not all circuits in the bathroom are RCD protected. Also if it is to be signed off under 16th then you cant add in bits from the 17th. It has to be one or t'other

 

[loopy]

thanks saveloy hmmm tricky plus its a huge job of high rise new living flats ....in my view if they put the lights on the 30ma side of the rcd due to circuit being within bathroom and no supplementary in place then all else falls into place am i right? jus noteing on the certificate no 30ma rcd protec circuits 1-3 16th - 17th edition difference

 

[saveloy]

Ahh I understand now, it being a big job. I've only ever known the 17th. As I understand it under 16th supplementary bonding had to be installed regardless.

Is the plumbing in the bathrooms in plastic. If so then in the 17th OSG it states that there is no need for supplementary bonding. As I understand it, if there is plastic plumbing then you may be doing more harm than good by introducing an earth to the bathroom. This may be why there is no supplementary bonding in these flats.

 

[loopy]

hmmmmmm .... the pipes within the bathrooms are copper and bonded at point of entry to flat

 

[Kellie Welch]

I was under the impression that December 2008 was the cutoff for signing anything off 16th edition? I May be wrong though.

 

[kiwisparks]

hi, I'am a great user of RCBO's,no multi tripping! no doubt fitting them on the circuits , non protected, that concern you will balance the problem,providing you have the height for fitting within the consumer unit, and not overlooking 701.415.2 ......... cheers

 

[saveloy]

hmmmmmm .... the pipes within the bathrooms are copper and bonded at point of entry to flat

When you say the pipes are bonded, do you mean main equipotential bonding?

If you were to put the bathroom lighting on to an 30ma rcbo, and could confirm that the resistance from any extraneous parts back to the MET, was less than 1666 ohms, and dissconnecton times can be met, then under 17th edition supplementary bonding could be ommited. However there is still the question of what version of the regs would the job be signed off under.

I may well be wrong, so please go easy but
It still sounds like there is a bit of mix and match going on Ie designed and installed under 16th with bits of 17th used when it suits.

 

[diditrain]

Slightly off the topic but i was just wondering what others are doing if they go to upgrade an installation to the seventeenth edition.

What do you do with the existing supplementary bonding. Do you disconnect it and then perform your tests to see what needed to be supplementary bonded or are you leaving it in place.

 

[Spudnik]

May as well leave it in place.

It would need to be there anyway, if the tests didnt prove satisfactory.

 

[Lou7]

As long as main bonding is done, RCD protection and disconnection times are OK then no supplementary bonding is required.

 

[zupos40]

When you say the pipes are bonded, do you mean main equipotential bonding?

If you were to put the bathroom lighting on to an 30ma rcbo, and could confirm that the resistance from any extraneous parts back to the MET, was less than 1666 ohms, and dissconnecton times can be met, then under 17th edition supplementary bonding could be ommited. However there is still the question of what version of the regs would the job be signed off under.

I may well be wrong, so please go easy but
It still sounds like there is a bit of mix and match going on Ie designed and installed under 16th with bits of 17th used when it suits.

Sorry it not 1666 ohms, but 0.005 ohms or less GN.3

 

[saveloy]

Sorry it not 1666 ohms, but 0.005 ohms or less GN.3

Sorry but you have not read my post properly.
In a bathroom that has all cicuits rcd protected,
disconnection times can be met and
all extraneous conductive parts are effectively connected via the protective bonding to the MET,
then supplementary bonding can be ommited.

Regulation 415.2.2 states that where doubt exists regarding the
effectiveness of supplementary equipotential bonding, it shall be confirmed
that the resistance R between simultaneously accessible conductive parts
and extraneous conductive parts fulfils the following condition:


R ≤ 50V / Ia for a.c. systems
By example, using a 30mA RCD (Required by 415.1.1)
R ≤ 50V / 30mA = 1667 ohms

With a Continuity tester on the Ohms setting, test between each metal pipe
that enters the bathroom (Extraneous conductive parts) and the circuit
protective conductor (cpc) of each electrical circuit in the bathroom.
If the reading obtained is less than 1667ohms and all circuits are protected
by 30mA RCD’s then no Supplementary Bonding is required.
If any of the above requirements cannot be met, Supplementary Bonding
must be installed.

Oh and it is 0.05 ohms and not 0.005. GN3

 

[zupos40]

Sorry but you have not read my post properly.
In a bathroom that has all cicuits rcd protected,
disconnection times can be met and
all extraneous conductive parts are effectively connected via the protective bonding to the MET,
then supplementary bonding can be ommited.

Regulation 415.2.2 states that where doubt exists regarding the
effectiveness of supplementary equipotential bonding, it shall be confirmed
that the resistance R between simultaneously accessible conductive parts
and extraneous conductive parts fulfils the following condition:


R ≤ 50V / Ia for a.c. systems
By example, using a 30mA RCD (Required by 415.1.1)
R ≤ 50V / 30mA = 1667 ohms

With a Continuity tester on the Ohms setting, test between each metal pipe
that enters the bathroom (Extraneous conductive parts) and the circuit
protective conductor (cpc) of each electrical circuit in the bathroom.
If the reading obtained is less than 1667ohms and all circuits are protected
by 30mA RCD’s then no Supplementary Bonding is required.
If any of the above requirements cannot be met, Supplementary Bonding
must be installed.

Oh and it is 0.05 ohms and not 0.005. GN3

Sorry for the error I keep adding extra o, I alway assumed that regulation refering to resistance R between simultaneously accessible conductive parts and extraneous conductive parts was used if disconnection times could not be met etc and the Ia was current which would cause automatic disconnection of the protective device within 5 sec, (BS7671:2004).

Thank I learnt something new tonight.