Supplementary Bonding - How was it wired?

[Midwest]

Alot of the properties I work in, were built when the 16th Edit ruled, most with no RCD's for bathroom lighting. Majority have evidence of supplementary bonding, clamps & earth wires on basin pipework, rads etc, or in immersion heater cupboards. However, some have no sign of that. Now I've read reg 701.415.2 & 415.2.2, so you can test for the effectivness of the earthing, but I never worked under the 16th Edit, so what should I expect to see. I've mentioned earth clamps etc, but the wiring diagrams I've seen, show bonding from cpc's to extraneous conductive parts, how do you connect a 4mm cable in a light fitting? I've also read on this forum, that the supplementary bonding should not go back to the MET, but I've seen tell tell signs of 4mm earth cables in CU? So how was it installed?

 

[Clive P]

Hi,

Back in the days of the 15/16th the norm then was to run a 6mm to the bathroom from the MET/CU and bond everything in the bathroom , lighting, pipework etc as a radial circuit. Times have changed but I personally liked the idea; and yes it was sometimes a pain in the a** to make off some of the connections.

Regards.

 

[Fin170]

Well connecting a 4mm to a lighting circuit is easy, assuming you don't use pull cords

From what I've seen the norm was not to bother but failing that just connecting everything to everything else and to take it back to the MET was just good practise

 

[guest119]

Bathrooms required equipotential bonding.
Theory being to bond together every bit of pipework coming in.
IE if the bath taps, basin taps, radiator etc were bonded together then there is no possibility of a voltage appearing between any points and hurting somebody who at that time will be at their most vulnerable, naked, wet, condensation everywhere.
Heating pipes and domestic supplies are capable of bringing in a voltage. Boiler, pump, immerser etc can develop faults.
I dont remember having to include lighting.
Lighting rules were no pendant type fitting on which condensation could run down the flex into the lampholder. Batten lampholder with a Home Office Skirt or enclosed fitting only.



Taking it back to the met is a different thing, EARTHED equipotential bonding.

Boydy

 

[Midwest]

Blimey home office skirt batternholder, I remember that, wonder where the name came from (wot was the IP rating!). I've read on here quite a few times that bringing earth cable from cu into the bathroom was big no no. Is that why all the diagrams show wired to cpc. I've seem quite a few with 4mm's back to CU though.

 

[Midwest]

Has anyone wired to or come across connecting a supplementary bonding conductor to a lighting cpc?

 

[Geoffsd]

just connecting everything to everything else and to take it back to the MET was just good practise

No, it wasn't.

 

[skydog23]

Back In The days before RCD's,everything was supplementary bonded, metal windows, doors, drainpipes, door hinges and handles even the dogs metal dog tag.
If it was metal and the was a chance it could become live it was classed as an extraneous conductive part and bonded. Lol
When it came to an airing cupboard, plumbers would say it the sparks job and sparks would say the plumber should have bonded all the pipes together. bonding had to be bonded. I even bonded my car when I parked it into the garage at night, in case it rose to a dangerous potential overnight. Lol.
Prays The Lord for RCD's Loling around the floor rolling my a## off

 

[telectrix]

now that bit about the car is totally wrong. should have had it's own TT earthing, independent of the house. :driving:

 

[Knobhead]

It’s quite simple, if it don’t move and it’s metallic, slap a f***in* big earth on it.
No extraneous earth cobblers. Metallic, it’s earthed!
Window frames were a bit extreme. But between the various versions of the regulations who can’t point to brain farts on the part of the IEE/IET over the years.

Just keep in the back of your mind, Mr Cockburn was MIET.

Hang on, so am I!

 

[Deleted member 9648]

Has anyone wired to or come across connecting a supplementary bonding conductor to a lighting cpc?

Yes,done it and seen it done,the idea was to connect extraneous CP's to conductive parts within the location...which included the lighting circuit.

 

[Midwest]

Yes,done it and seen it done,the idea was to connect extraneous CP's to conductive parts within the location...which included the lighting circuit.

That's one person so far, interested to know how your terminated the cable!

 

[SPARTYKUS]

That's one person so far, interested to know how your terminated the cable!

If you mean a normal light pendant then there is usually a fair a
sized earth terminal. 4mm will fit in it, as long as it is not deformed/mangled. Keep its cross section the way it was when it was made... A perfect circle. Then there is a slim chance you may also get the other cpc's in. If not join them together another way within the enclosure, as in a choccy block (oh no!!!!!).with a bigger hole.

not sure what you're getting at....?

 

[Midwest]

I'm going to do a job, where there's no obvious sign of supplementary bonding, i.e. on bathroom rads, pipes etc. Nothing in the cu. So I started this thread just to know where else to check, before I test pipework continuity.

 

[Des 56]

That's one person so far, interested to know how your terminated the cable!

Taking a bond to the Bathrom lighting circuit was standard,not rare practice

I have seen literally hundreds of installations where the lighting has been done this way

Many of these had a rising cable near where the bathroom pull cord was located,if the terminal was not meaty enough,then a connector block was fitted
The supplementary bonding could also be found external to the Bathroom,in a nearby cupboard etc

 

[Midwest]

Taking a bond to the Bathrom lighting circuit was standard,not rare practice

I have seen literally hundreds of installations where the lighting has been done this way

Many of these had a rising cable near where the bathroom pull cord was located,if the terminal was not meaty enough,then a connector block was fitted
The supplementary bonding could also be found external to the Bathroom,in a nearby cupboard etc

Yes thanks seen bonding in nearby cupboard, just never seen it taken from a light, so I just wondered if that was ever practised and it seems it was.

 

[LeeH]

Hot to cold to rad to light CPC was the norm when I was at sparky school.

Not done any domestic work since then mind you.

 

[kingeri]

In my own bathroom, the pipework is all bonded together, together with the shower, towel rail and lighting CPCs. The 4mm goes up through the airing cupboard and into a downlight junction box.

 

[SPARTYKUS]

In my loft, all cpcs are twisted together. Outside the JBs. :shades_smile:

 

[Geoffsd]

just to know where else to check, before I test pipework continuity.

Wouldn't it be better to test first.

It may not be required.

 

[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:

 

[SPARTYKUS]

Reading G8 now, what page? :clap:

Er, ah..... I'll take the zero out of ten on that one!!

not near my copy, sorry. You'll just have to read through the whole book )

 

[Midwest]

Dooooh, just trying to cheat.

 

[Richard Burns]

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