17th edition bathroom eq. bonding wiki

[Spark123]

Hi, I have started to try and update the supp bonding wiki for the 17th edition here: //www.diynot.com/wiki/electrics:supbond17th
Any comments / corrections?

edit, have made it a live copy.

 

[Taylortwocities]

Looks a good job to me.

There's a link to "Supplementary equipotential bonding"

there's a link to an NICEIC drawing of supp bonding but they meanies have taken that info off their site.

I've posted an image

Supplementary Bonding

• Taylortwocities
• 11 Sep 2008
• 1

or there's this article

http://www2.theiet.org/Publish/WireRegs/WiringMatters/Documents/Issue2
2/2007_22_spring_wiring_matters_equipotential_bonding.pdf

 

[Spark123]

I have left the old one on for now, is it this one with the links a the bottom which you mean?

 

[ebee]

Is anyone else concerned that supplementary bonding may be omitted if something with a 7% failure rate (RCD) is in place?

 

[sm1thson]

Is anyone else concerned that supplementary bonding may be omitted if something with a 7% failure rate (RCD) is in place?

^7% for what? on arrival? within one year? within 5 years? if a fail is out of spec how many actually fail completely?

I am not a spark but my passing observation is that in a lot of split load boards they rely on diversity to not take the RCD beyond its maximum current, and there are a number of other installations where a DIYer has then added a shower again possibly pulling too much current through the RCD, this cant be good. - Ive never seen anything to quantify what damage this does and how much of a contributing factor this is to the RCD failures you describe. Most typical 17th edition setups help relive stress on the RCDs maybe this will help, and although it has been a requirement to test foreverlong i suspect that more tests are been done nowadays with the requirements of self certify schemes etc, this should also help.

 

[BS3036]

Spark123: Thanks for this summary. I took the liberty of correcting a few spelling typos.

I am still trying to get my head fully round this subject, especially with the 17th, as I haven't actually been personally involved with implementing supplementary bonding before. So I'm wondering if a little scene-setting wouldn't be in order at the start of the article. Kind of like philosophy of protection with 16th, and then with 17th.

As for this 7% stuff, my first reaction is: the previous situation didn't require an RCD, but did require everything joined to earth. The new situation does require an RCD but doesn't require things which are already joined to earth to be joined again. Which sounds safer on the face of it.

I suppose the difference is that:
a) the situation could change without being visible (earths could disappear)
b) non-extraneous metal work could become extraneous without a visible change.

Apologies for my incorrect use of terminology...

 

[Taylortwocities]

I have left the old one on for now, is it this one with the links a the bottom which you mean?

Its the NICEIC link on the following that doesnt work

//www.diynot.com/wiki/electric...l_bonding:supplementary_equipotential_bonding

 

[ban-all-sheds]

This link:

http://web.archive.org/web/20051231060046/http://www.niceic.org.uk/downloads/NL139supp.pdf

??

Works fine..

 

[ban-all-sheds]

Hi, I have started to try and update the supp bonding wiki for the 17th edition, I have started to compile a draft copy here: //www.diynot.com/wiki/electrics:supbond17thdraft
Any comments / corrections?

It'd be useful to find a nice online 3D perspective drawing of the new zones...

Anybody come across one?

 

[Spark123]

I'll see if I can find a 16th edition one which can be modified - I think bathroom zones are in a separate wiki.

Cheers BS3036, speeling isn't my stringest point

 

[ebee]

Research suggests a failure rate of RCDs to be 7% or so!

 

[Taylortwocities]

Is that 7% a year, an hour or what
For Chint/Volex it could be true, For MEM/HAger/MK, etc ??
What research is that? Where's the provenance.

 

[ban-all-sheds]

What research is that? Where's the provenance.

Here: http://esc.org.uk/pdfs/news-and-events/research/rcd/Final_Report.pdf

It's not 7%.

Background:


http://www.era.co.uk/news/pr0709.asp

http://www.escweb.org.uk/news-and-events/latest-news/RCD-Reliability-Investigation-id-22.html

http://esc.org.uk/news-and-events/research/industry/rcd/

 

[ebee]

"Previous research published in Italy indicated that electromechanical RCDs had an average failure rate of 7.1%. However, if the RCDs were operated regularly by means of the integral test button, this figure fell to 2.8%, indicating that RCD reliability improved if they had been operated regularly."

I don`t think that the figure of 7% I mentioned is unreasonable though! do you?

In my experience RCDs tend to either work or fail unsafe.
By fail unsafe I mean fail to work at all rather than be too sensitive which I would call fail safe I suppose.
Of those that work I include those that trip but outside the specified times.
Frequent pressing of the test button to stop any "stickiness" by the mechanism seems to improve things but in reality despite test notices it is rare for people to do this.

 

[ban-all-sheds]

I don`t think that the figure of 7% I mentioned is unreasonable though! do you?

YES