Supplementary Bonding - How was it wired?

[Midwest]

Wouldn't it be better to test first.

It may not be required.

That's what I'll do, but would be nice to see them in place before doing so.

 

[Guest111]

Years ago Ali windows were bonded,that stopped when a fault on a house made all the earths live and a window cleaner got electrocuted,I also remember when there was talk of making all metal outside lights have to be rodded,there was great debate about the aesthetics of a 6mm g/y running down the front wall of a house,needless to say it never happened but someone at the IEE obviously thought it was a good idea.

 

[tom79bmth]

Pretty sure on the 16th edition they made amendment to supplementary bonding where all circuits had to be linked IE shower lighting circuits I think it was about 10 years ago then it was changed back again

 

[Geoffsd]

That's what I'll do, but would be nice to see them in place before doing so.

But if the situation is such that supplementary bonding is not required then there will be nothing to see.

Testing/measuring is the only way to tell if it is required.

 

[Midwest]

Point taken

 

[guest119]

1985 doing the 15th 5 night update we were told to hose the bathroom window from outside then go indoors and measure the frames resistance to earth.
Any reading at all and it was to be bonded.

Boydy

 

[7029 dave]

Nobody has mentioned bonding the old cast iron baths back in the day.

 

[kingeri]

My old bath had an earthing terminal underneath it!

 

[Silly Sausage]

My old bath had an earthing terminal underneath it!

My bath has two big 230V motors underneath it.
Must get that panel put back on.

Not a supp bond in sight.

 

[Midwest]

I was going to do my continuity tests, and was quite confident that using the formulae from reg. 415.2.2; R< 50/Ia ,where in the case of a 6amp BS EN 60898 MCB Ia = 30amp. Therefore R=50/30 < (less than) 1.666ohms. However, talking to another electrician, he said the reading should be below 0.05ohms. Can anyone advise?

 

[telectrix]

where a RCD is fitted, R<= 1667. the 0.05 is considered to be a negligible resistance between different extraneous metal parts and MET. in other words, the OCPD is guaranteed to trip within the required time.

 

[Geoffsd]

I was going to do my continuity tests, and was quite confident that using the formulae from reg. 415.2.2; R< 50/Ia ,where in the case of a 6amp BS EN 60898 MCB Ia = 30amp. Therefore R=50/30 < (less than) 1.666ohms. However, talking to another electrician, he said the reading should be below 0.05ohms. Can anyone advise?

You are correct.

 

[Midwest]

where a RCD is fitted, R<= 1667. the 0.05 is considered to be a negligible resistance between different extraneous metal parts and MET. in other words, the OCPD is guaranteed to trip within the required time.

So what is 'reg. 415.2.2; R< 50/Ia' for?

 

[Geoffsd]

So what is 'reg. 415.2.2; R< 50/Ia' for?

If the protective device is an RCD then R ≤ 50/Ia of RCD = 50/0.03 = 1666

If an MCB then R ≤ 50/Ia of MCB (30,50,80,100,125.160,200,225,250 or 315)

 

[Midwest]

I was going to do my continuity tests, and was quite confident that using the formulae from reg. 415.2.2; R< 50/Ia ,where in the case of a 6amp BS EN 60898 MCB Ia = 30amp. Therefore R=50/30 < (less than) 1.666ohms. However, talking to another electrician, he said the reading should be below 0.05ohms. Can anyone advise?

Did my tests. Pipes in heater cupboard, all 0.00-0.05ohms. Same pipes to MET, 0.00-0.05ohms. Extraneous conductive parts in bathroom (i.e. cold & hot supply to basin & rads & connecting pipework) > 99.9kohms. Same result to cpc of circuits in bathroom. On inspection of cupboard under kitchen sink, plastic water main to plastic pipe, to short peice of copper to sink. I suspect the house is plumbed predominantly in plastic pipe, with the last visible peice in copper, which I believe does not require bonding.

 

[Geoffsd]

Pipes in heater cupboard, all 0.00-0.05ohms. Same pipes to MET, 0.00-0.05ohms.

It would seem they are already bonded and satisfactory.
0.05 is just an accepted value of negligible impedance and does not relate to any test as such, other than a satisfactory connection.

Extraneous conductive parts in bathroom (i.e. cold & hot supply to basin & rads & connecting pipework) > 99.9kohms. Same result to cpc of circuits in bathroom.

Then they do not require bonding and should not be bonded.
If that is the maximum range reading it could be a lot higher. You could test with IR.

On inspection of cupboard under kitchen sink, plastic water main to plastic pipe, to short peice of copper to sink. I suspect the house is plumbed predominantly in plastic pipe, with the last visible peice in copper, which I believe does not require bonding.

Correct.

 

[Midwest]

Thanks All

 

[Midwest]

Out of interest; I was reading somewhere on this forum that if the R < 1667ohms, the extra' cond' should be bonded R> 22kohms it does not, I know that's noy quite right, but I can't find that thread now. What formulea are used for such figures, and where does that appear in the regs?

 

[SPARTYKUS]

I believe all would be revealed in GN8 (guidance note 8) - the earthing and bonding one. Pretty sure its in that one. If not then its GN3, the testing and inspection one.

 

[Midwest]

I believe all would be revealed in GN8 (guidance note 8) - the earthing and bonding one. Pretty sure its in that one. If not then its GN3, the testing and inspection one.

Reading G8 now, what page? :clap: