Earthing water. Part plastic, part copper

[robsparx]

On the job I'm at, there is a plastic incoming water main, with a plastic pipe taken from it on the consumer side. The plastic runs up into a bathroom and copper pipe is taken off it to supply the bathroom. The plastic pipe carries on up into the loft which i then assume feeds more copper pipework.

As I see it, there is no requirement for supplementary bonding, as the copper is supplied by plastic. But there would be a requirement to earth any copper installation if it is introducing earth potential.

Would that mean I would have to seperately earth every piece of copper installation that is teed off the plastic. Not had too much experiences with plastic pipes before.

 

[Guitarist]

Always a tough one to call for the following reasons... If you have an electrically separate piece of copper pipe somewhere near the plastic incomer, plus bits of copper piping in the rest of the installation AND you test between this short piece (plus all your other pipes) and the MET and you get in excess of 23k ohms, then you could confidently say (as others have pointed out) that this pipework is not going to introduce a potential.
However, a year down the line, the homeowner has a boiler fitted and the conscientious plumber arranges for a sparky to main bond the incoming gas pipe. Said sparky slaps his 10mm cable in and goes home happy.
Unfortunately, now we have some continuity between the pipework in the system, but it's not perfect and we get some resistance. Now, if someone were to get a shock (for whatever reason), the first question would be "Why wasn't the main water incomer bonded?"

I realise that I have painted a bit of a far-fetched scenario, but I think this is a why most electricians would say "If it's not all plastic then put a 10mm main bond in". That way, if it anything gets altered then you have covered yourself.

 

[Geoffsd]

For your own peace of mind, bond the copper work. Saves the grief in the future when your held accountable for something going badly wrong.

There may be grief because parts have been bonded unnecessarily and introduced a hazard.

What about the proverbial spoon?

 

[Geoffsd]

"Why wasn't the main water incomer bonded?".

Because it is not an extraneous conductive part.

 

[Guitarist]

Because it is not an extraneous conductive part.

I made that point mate during the post so that quote is really out of context. I am merely playing devils advocate, which I thought was obvious...

 

[Geoffsd]

I made that point mate during the post so that quote is really out of context. I am merely playing devils advocate, which I thought was obvious...

Sorry if I misunderstood...

But introducing a properly bonded gas supply will not alter the status of the water pipes as far as main bonding is concerned.

 

[Astro800]

Too much responsibility:juggle2: I'm going to be a Painter & Decorator, EASY LIFE :39:

 

[Guitarist]

Personally, I hate seeing bits of plastic interspersed amongst copper pipework, some in contact with other services and some not. About 20 years ago I was asked to bond all the pipework in a renovated house.... imagine my horror when I found the odd plastic push-fit elbow throughout the system. Took me ages to strap across all these "breaks" in the system.

 

[telectrix]

Too much responsibility:juggle2: I'm going to be a Painter & Decorator, EASY LIFE :39:

it's a 3 day course.

day 1. how to open a tin of paint.

day 2. how to transfer said paint on to floors,stepladders, worktops and into electrical accessories.

day 3.(the technical part of the course) . perfecting aim into toolboxes.

 

[Knobhead]

You forgot part of day 2. How to replenish the paint on the sole of your trainers.

 

[telectrix]

and the advanced module, day 3. evening....... how to get paint through windows onto parked vans.

 

[Knobhead]

and the advanced module, day 3. evening....... how to get paint through windows onto parked vans.

Don’t remind me!
View attachment 11816
We had these cranes repainted. It cost the painters a fortune to have 20 cars re-sprayed when the mist of paint drifted over the car park. Lucky for them the plant was shut down, normally there would be 100+ cars there.