How can you Earth Bond plastic incoming mains water pipe?

[Des 56]

as widdler states 544.1.2 as near as practicable or after any insulating section. which is the only reg that actually gives any real wording on the matter. but with a site manager, qs and unresponsive advice from niceic i think the area should be addressed a bit more clearly within the regs.

eitherway im fitting bonding at first available point wether it returns to plastic, copper or kryptonite and they can all go jump!

Now thats what I call free thinking and good on you for that attitude

All of us who may "think" we understand the objective of the regulation, has right on our side

If that objective is made much more definitive by the regulation makers,everybidy, the pretend regulation makers, (we know who that is) and sparks everywhere should be "as one" with the interpretation of what and where to bond

It does need sorting

 

[tonys]

eitherway im fitting bonding at first available point wether it returns to plastic, copper or kryptonite and they can all go jump!

If you feel there's a reasonable possibility that the pipe in question could introduce a potential, then you have make that final decision, to bond or not to bond

Ive seen plenty of sparks run a 10mm into the cylinder cupboard, and cross every pipe to make sure.

 

[pushrod]

I use 23K Ohm, derived from a 10mA fault current.

This is the overall value i'm thinking of but when you measure it you are looking for 22kΩ as you take the human body to have a resistance of 1000Ω.


Lenny (re that link) i would not be happy with taking 6667Ω as the value for an extraneous conductor as that could allow 29mA of current to flow and a grip response (ie the person being shocked can't let go) can be exhibited at 20mA. whereas the 23kΩ figure gives 10mA to which the body response is release/jump back. Surprised that niceic put their faith in that value.

 

[ELEKTRIC]

DETERMINING IF A PART IS EXTRANEOUS OR JUST A PIECE OF METAL​

A test should be made using an Insulation Resistance Tester set on MΩ, supplying 500 Volts.
Test procedure:
Connect one test lead to the metal part and the other lead to a known earth. (MET)
If the resistance value is 0.02MΩ (20000Ω) or greater, no supplementary bonding conductor is required.
If it is less than 0.02MΩ, supplementary bonding should be carried out.
From the Ohm’s law:
I = V / R; I = 500V / 20000Ω = 0.025Amp
This shows that if the fault was on a single phase 230Volt supply the current that would flow between the conductive parts would of course be only 0.012Amp.
This current is unlikely to give a fatal shock

GN8 and GN5: if extraneous metalwork is above 22KΩ then it need not be supplementary bonded.

 

[telectrix]

only problem as i see it is, what IR testers or MFTs have that kind of accuracy at such a low value?

 

[tonys]

16th Edition citb study notes used to state 0.25 megohm, but with a visual inspection. So I suppose if you can not inspect the entire length of the metallic object, you should not rely upon the test alone?