Plastic Water main with copper throughout.

[rattlehead85]

Was called to a job yesterday where a company had completed an EICR on a house fed via a plastic water main with internal plumbing done completely in copper. They had put a c2 observation code for a lack of main protective bonding to the water. The customer had shown me the EIC cert she had been given by the original company who had completed a rewire on her property.
Disconnecting the earthing conductor at the intake position and completing an IR test to the internal stopcock on the water gave me a reading of 0 megohms. To me this has indicated that somewhere within this installation the copper pipework is earthy and deemed extraneous and does warrant a main bond. I did think this could be gaining a reading through the boiler gas connection (which is bonded) I am leaning on the side of advising the client to get the original contractor back to sort this. Opinions on this before doing so would be appreciated.

 

[spark 68]

Re: Plastic Water main with coper throughout.

What was the actual reading back to the MET ?, not the 0 Mohm one though, the actual R2 for want of a better term.

 

[rattlehead85]

Re: Plastic Water main with coper throughout.

.09 mate. Today i have been told that the original contractor had returned and told the client the water is already bonded as the gas is done and feeds the water through the heating system pipework. Apparently the water according to them didn't require a direct bond as the incomer is plastic. I pointed out this is incorrect and backed it up with the use of the osg but now have been accused of trying to source work.!!

 

[spark 68]

Re: Plastic Water main with coper throughout.

.09 mate. Today i have been told that the original contractor had returned and told the client the water is already bonded as the gas is done and feeds the water through the heating system pipework. Apparently the water according to them didn't require a direct bond as the incomer is plastic. I pointed out this is incorrect and backed it up with the use of the osg but now have been accused of trying to source work.!!

If the incomer is plastic then it is not introducing an Earth potential from outside at that point, my next move is to see how low the reading actually is back to the met, and if it is around the suggested 0.05 mark as per GN3 I assume it is bonded via the gas (boiler) so long as I can see and verify the gas bond.

I usually look to see if it is below say about 0.1 or above 23k to decide if it needs it or not, I usually look at the approximate length of the run and see if it matches the expected R2 value as per the tables.

 

[rattlehead85]

Re: Plastic Water main with coper throughout.

Well i verified the gas bond as compliant. The readings i got indicated to me that the water was extraneous. What i cant prove is if the water really is getting its earth through the gas or wether there is an inaccessible pipe concealed behind panelling which may be making contact with earth which would deem the service to be bringing an earth potential into the property within its own right. I'm thinking that due to this possibility a main protective bond at the stopcock position would be desirable.

 

[rattlehead85]

Re: Plastic Water main with coper throughout.

Im beginning to think this is what the company doing the EICR was thinking and that the rewire firm don't really know so they are using the fact they put an earth on the ga s as their --- covering strategy.

 

[Engineer54]

Re: Plastic Water main with coper throughout.

All depends if the metal water pipe after the stopcock enters the slab again, or in the case of blocks of flats passes bare through, or in the floor slabs or run buried in coluums, where they will almost certainly become extraneous..

 

[rattlehead85]

Re: Plastic Water main with coper throughout.

The stopcock is under the kitchen sink it then bends and runs clipped to the wall into a service void which i cannot access as it is tiled and decorated. This service void runs up to the bathroom directly above where i can see a water pipe and a metal soil pipe in a cupboard which incidentally have no visible signs of bonding...

 

[spark 68]

Re: Plastic Water main with coper throughout.

I would also disconnect the Gas bond at the MET and measure across the gas and water pipes.

On normal houses where the incomer is plastic , unless I see evidence of either an outside metallic pipe (garden tap etc.) or an outbuilding with a water supply, it is fairly safe to say that it won't be bringing in an Earth potential from outside.

The metal soil pipe would need further investigation though.

 

[rattlehead85]

Re: Plastic Water main with coper throughout.

The soil pipe is most def extraneous. I verified this back to the earthing conductor and needs bonding. What i also considered was the possibility that somebody has cross linked the pipes behind the panel along with the soil pipe therefore this would explain why i get a reading off the water at the stopcock point. As i said im leaning towards asking for a bond to be placed at the stopcock as the circumstances relating to this are telling me that for whatever reason the water is earthy. Question is would there be any adverse effects from bonding the water independently along with the soil waste.

 

[spark 68]

Re: Plastic Water main with coper throughout.

. Question is would there be any adverse effects from bonding the water independently along with the soil waste.

No adverse effects, as in this case it is already effectively bonded via the gas by that reading, apart from the difficulty of routing the MPB that is

You could always add it as near as practicable if you feel it needs it.

 

[Geordie Spark]

Re: Plastic Water main with coper throughout.

Well i verified the gas bond as compliant. The readings i got indicated to me that the water was extraneous. What i cant prove is if the water really is getting its earth through the gas or wether there is an inaccessible pipe concealed behind panelling which may be making contact with earth which would deem the service to be bringing an earth potential into the property within its own right. I'm thinking that due to this possibility a main protective bond at the stopcock position would be desirable.

You can if you dis the gas supply from the boiler.

 

[rattlehead85]

Re: Plastic Water main with coper throughout.

You can if you dis the gas supply from the boiler.

Agreed [emoji1][emoji1][emoji1] prob is i aint gas safe to do so and im damn sure i aint putting my --- in court over a job which i was only asked to give an opinion on.

 

[rattlehead85]

Re: Plastic Water main with coper throughout.

Im going to compile a covering letter outlining the reasons why i feel the company who did the EICR are correct in saying the water requires a main bond. Using the OSG and BYB i can show why a main bond would be desirable. The findings are relatively inconclusive so in this situation i would suggest bonding the water as a bond to the soil is most definitely absent and needed and a link onto the water at this point is relatively easy to do. The fact that adding a bond will not incur a hazardous condition makes it sensible to do the job and eliminate the uncertainty in the process.[emoji106]

 

[davesparks]

Re: Plastic Water main with coper throughout.

If the results of your test on the water main have been affected by the main bond to the gas then you have not carried out the test correctly.

Isolate the installation, then disconnect the earthing conductor from the MET (or remove test link). You then test between the incoming earth and the suspected extraneous part.

I'm not surprised you have been accused of trying to get work by unscrupulous means, a plastic water main which feeds surface clipped installation pipework is unlikely to be extraneous.

 

[davesparks]

Re: Plastic Water main with coper throughout.

, my next move is to see how low the reading actually is back to the met, and if it is around the suggested 0.05 mark as per GN3 .

That 0.05 is the suggested max resistance between a pipe and the electrical connection of the earthing clamp, NOT the resistance of the bonding conductor!

 

[rattlehead85]

Re: Plastic Water main with coper throughout.

Can you please read through the whole thread. You'll find that that is exactly what i did!!

 

[davesparks]

Re: Plastic Water main with coper throughout.

Can you please read through the whole thread. You'll find that that is exactly what i did!!

I did, you said you thought the low reading may be due to the main bond on the gas. Therefore you must have carried out the test incorrectly for it to be possible for the gas bond to influence the test result.

 

[spark 68]

Re: Plastic Water main with coper throughout.

That 0.05 is the suggested max resistance between a pipe and the electrical connection of the earthing clamp, NOT the resistance of the bonding conductor

I know, in domestic though you would need a bloody long run to really exceed that my much if it was 10mm, I did say to take into account and check against the tables.

And it is between "points" not necessarily the connection between the clamp and a pipe.

 

[rattlehead85]

Re: Plastic Water main with coper throughout.

I didn't just say it was extraneous for the sake of it and if you had bothered to read the thread you'd see i was asked for an opinion only not price for any potential work!!