Bonding Cast Iron Pipe

[bureaucrazy]

Hello.
The toilet is connected into a cast iron waste/soil pipe O.D. 150mm.
Apparently, this is an extraneous conductive part and is thus supposed to have a main protective bonding conductor connected back to the MET.

There is a bonding clamp for 150mm O.D. pipes available.

However, the pipe will be painted to prevent further corrosion, so the contact with the clamp will be poor.
If paint is removed to contact the clamp, the pipe will corrode due to the high humidity of the location.

Would rather not drill or screw anything into the pipe.

What is the correct way to deal with this? If the pipe is painted so that it is not conductive enough to have continuity with a bonding clamp, perhaps it is not conductive enough to warrant bonding?

According to the regs, it seems this needs bonding. According to the EICR guide, missing main bonding is a code 2 fail.

Would any of you code a lack of bonding of a soil pipe on an EICR?

What is the standard way to deal with this and comply with the regs?

 

[Spoon]

Has the waste pipe actually been tested to see if it's an extraneous conductive part?

 

[Sintra]

Firstly I would test to see if it is actually extraneous rather than being told that it is.

RCP >U0–ZTL where: Rcp is the measured resistance between the conductive part concerned and the MET of the installation (in ohms), Uo is the nominal voltage to Earth of the installation (in volts), Ib is the value of current through the human body (or livestock) which should not be exceeded (in amperes), and Ztl is the impedance of the human body or livestock (in ohms). Guide to effects of current on human beings and livestock provides data for Ztl and Ib. For hand-to-hand contact, the value of the body impedance is given as 1000 Ohms in dry conditions where Uo is 230 V. You can then select a value of Ib between the two extremes: 0.5 mA – the threshold of perception and 10 mA – the let-go threshold Rcp>(Uo/Ib)–Ztl=(230/0.01)-1000=23000–1000=22Kohms

 

[pirate]

Angle grinder, scrape the paint off. big Jubilee clip, bond it, paint over...them find somewhere to connect your cable...and do a nice laminated label

 

[pirate]

Clearly out of my depth here...

 

[davesparks]

Assuming bonding is needed then clean the paint off, fit an earth strap like the ones used for lightning protection systems. These are made of a copper band which clamps around the pipe and can be easily painted over leaving a copper tag sticking out to connect the main bond onto.

Something like this Pipe Bonds - https://www.jointingtech.co.uk/Pipe-Bonds

 

[Megawatt]

Assuming bonding is needed then clean the paint off, fit an earth strap like the ones used for lightning protection systems. These are made of a copper band which clamps around the pipe and can be easily painted over leaving a copper tag sticking out to connect the main bond onto.

Something like this Pipe Bonds - https://www.jointingtech.co.uk/Pipe-Bonds

Does the pipe have flanges with bolts?

 

[Pete999]

Hello.
The toilet is connected into a cast iron waste/soil pipe O.D. 150mm.
Apparently, this is an extraneous conductive part and is thus supposed to have a main protective bonding conductor connected back to the MET.

There is a bonding clamp for 150mm O.D. pipes available.

However, the pipe will be painted to prevent further corrosion, so the contact with the clamp will be poor.
If paint is removed to contact the clamp, the pipe will corrode due to the high humidity of the location.

Would rather not drill or screw anything into the pipe.

What is the correct way to deal with this? If the pipe is painted so that it is not conductive enough to have continuity with a bonding clamp, perhaps it is not conductive enough to warrant bonding?

According to the regs, it seems this needs bonding. According to the EICR guide, missing main bonding is a code 2 fail.

Would any of you code a lack of bonding of a soil pipe on an EICR?

What is the standard way to deal with this and comply with the regs?

Apparently this is an "extraneous part", who says? has it been tested to see if it actually is an extraneous part?

 

[davesparks]

Apparently this is an "extraneous part", who says? has it been tested to see if it actually is an extraneous part?

Obviously it does need testing but my experience is that cast iron soil stacks that are exposed within the installation do test as extraneous and need bonding.

 

[davesparks]

Does the pipe have flanges with bolts?

Not usually, old fashioned cast iron soil stacks in the UK had a socket at one end of the pipe which the next pipe slots in to. The joint was then packed with some kind of rope and caulked with a cement.

 

[Pete999]

Not usually, old fashioned cast iron soil stacks in the UK had a socket at one end of the pipe which the next pipe slots in to. The joint was then packed with some kind of rope and caulked with a cement.

Soil stacks are usually installed in a Bathroom, within which the electrics should be protect by an RCD! which MAY negate the need for bonding extraneous conductive parts.

 

[davesparks]

Soil stacks are usually installed in a Bathroom, within which the electrics should be protect by an RCD! which MAY negate the need for bonding extraneous conductive parts.

An RCD doesn't negate the need for main bonding, it only affects supplementary bonding.
Soil stacks pass through other rooms too, and the times I've had to bond them has been when they are exposed inside other rooms such as a garage or other lean-to type construction on the side of a house.

 

[Pete999]

A cast iron Soil stack could be considered as an Extraneous Conductive part, in fact it would require both main equipotential and Supplementary within the Bathroom. Unfortunately BS7671 does not consider service pipework which is not accessible.

 

[PEG]

When considering bonding connections,i would confirm that it is cast,and not wrought,steel or other...and i have seen aluminium and copper,painted,which confuses further.

I would test first,of course,but in larger,older properties,the bit which would ensure it's connection with terra,is usually the part altered first,and may well be plastic.

 

[Timbo]

Weld a tag on the pipe to bolt to.

 

[PEG]

Weld a tag on the pipe to bolt to.

....I would go steady,advising someone to weld a metal tube,directly connected to the waste system,with all it's possible vapours and gases...

Best case=can weld=no extra problems

2nd best case=poor weld=sanitary towel snagger

Worst case=can weld=methane=cast-iron pipe bomb and a letter of thanks,from everyone sat on the karzi,for their blue-water enema

 

[telectrix]

and some soil pipes ( like ours, 1950's ) are asbestos, painted over the years, look like metal but clout with a hammer gives a different sound. then the bit that goes from the bog, through the wall might be lead.

 

[Deleted account]

Realistically what are the chances of this being an issue.

If there is RCD protection I wouldn’t bother. If there isn’t I’d just supplementary bond it.

Obviously if someone has identified this as part of risk assesment and felt the need and pointed it out to you then do it and charge for it but I think it’s overkill.

As for original question how to bond it. Sorry never done it don’t know.

 

[bureaucrazy]

Thanks for the answers.

So, we have at least established that it is required to bond it or it may fail an EICR.

The pipe is definately cast iron and definately goes into the ground and has never been altered. A plumber told me the joins were made with lead. The pipe jutting into the bathroom has a lot of rust underneath that has been treated with rust converter.

What is the procedure to test it?

There are no flanges or similar places to attach to. I think removing a patch of paint down to bare, clean metal and then fitting the copper strip before painting over would be the best method to bond it.

Or, would it be possible to solder on a small metal tag with a soldreing iron?

What about removing a section of pipe outside and replacing it with plastic? (I may need to do this anyhow to fit a branch for a second toilet). Then it won't be able to introduce an earth potential will it?

 

[DPG]

Plastic replacement sounds favourite to me. It sounds like it's in a bit of a mess anyway.