Earth Bonding

[alanthomaswatson]

Some clarification please.

We recently had our water pipe replaced with a new MDPE pipe. After it enters the house there is a run of about 3m of 22mm copper which connects into a new plastic pipe. From there, there are various pipes of copper or plastic.

There is no earthing on the copper section. Should there be?

There is no earthing on the bathroom pipework, but we have a plastic bath and ceramic toilet and sink. Should there be?

I am installing a laundry with stainless steel sink but plastic pipe in the cellar. Do I need to earth bond the sink?

We have an old type Wylex board but the fuses have ben replaced with MCBs.

Any clarification much appreciated.

Alan

 

[Lectrician]

The main water pipe does NOR need need main protective bonding in your case. If the run was really easy and short, i would likely run one anyway, but if it is going to take longer than a few minutes I would not bother.

The bathroom pipework and bathroom circuits DO need supplementary bonding unless you had both main protective bonding and RCD protection of bathroom circuits (you have neither by the sounds of it).

The sink in the basement does NOT need any bonding.

 

[alanthomaswatson]

Lectrician

Thanks for the quick reply.

I'll connect up the main supply pipe as it's an easy 1m away from the fuseboard. Apologies if this is a dumb question but do I need to isolate anything before connecting to the earth bar?

For the bathroom, is it a case of running a cable and clamps between the hot and cold pipes under the bath? Is that enough?

 

[ban-all-sheds]

• NICEIC Earthing & Bonding leaflet
  
  
• What's an extraneous-conductive-part?
  
  
• Bonding & plastic pipes
  
  
• Bathrooms & the 17th
  
  
• Supplementary Equipotential Bonding

 

[alanthomaswatson]

Thanks for the reply

Bit more assistance if I may.

In effect, all the pipe under the bath and to sink and toilet are copper. These are fed by a plastic cold pipe. The hot water comes from the boiler in the bathroom which has a length of copper pipe then a plastic section connecting to the copper under the bath.

Essentially, the cold supply from start to finish goes:

MDPE underground-copper-plastic-copper

and the hot supply goes:

MDPE underground-copper-plastic-copper-BOILER-copper-plastic-copper.

Should all the parts of copper be linked together?

If not, the cold, hot and central heating pipes are all in a nice line under the boiler. Can I put a clamp on each one and connect that to the earth in a local socket? My conern with that is that teh benefit of the earthing is lost by the intermediate sections of plastic.

 

[ban-all-sheds]

The bathroom pipework and bathroom circuits DO need supplementary bonding unless you had both main protective bonding and RCD protection of bathroom circuits (you have neither by the sounds of it).

If the copper section after the incoming MDPE has no main bonding, what makes the copper sections in the bathroom extraneous-conductive-parts?

 

[ajrobb]

If the copper section after the incoming MDPE has no main bonding, what makes the copper sections in the bathroom extraneous-conductive-parts?

IF en electrical fault develops in the boiler AND/OR the CPC is broken...

 

[ban-all-sheds]

Does that scenario meet the definition of an extraneous-conductive-part?

A conductive part liable to introduce a potential, generally earth potential, and not forming part of the electrical installation.

Is the simultaneous failure of an appliance and it's cpc connection something which is liable to happen?

But I wasn't thinking about the boiler - the hot supply has yet another plastic section in this case.

 

[ban-all-sheds]

Can I put a clamp on each one and connect that to the earth in a local socket? My conern with that is that teh benefit of the earthing is lost by the intermediate sections of plastic.

No - even if the pipework was 100% copper you'd not connect it at the boiler to the earth of a nearby socket. Bonding and earthing are not the same, but don't worry - many professional electricians don't get that either.

 

[ajrobb]

With plastic pipes except at the boiler, a recent BC Part P inspection recommended I bond one of the boiler pipes back to the CU. The mains feed pipe was deemed a suitable choice for bonding.

 

[Spark123]

On what grounds did they require you to main protective bond a boiler pipe?

 

[ajrobb]

On what grounds did they require you to main protective bond a boiler pipe?

It was a recommendation only and not a requirement.

It just so happened that I still had what was left of the old 6mm² bonding conductor from the original 1970s copper plumbing. It was suggested that would be "better than nothing". The original bonding had been chopped off by kitchen fitters in the 1990s.

The main reason I went to plastic pipes was to avoid bonding.

Is the simultaneous failure of an appliance and it's cpc connection something which is liable to happen?

Given that the original CPC joints are all twisted and screwed, more liable than I'd like.

 

[dingbat]

Bonding and earthing are not the same, but don't worry - many professional electricians don't get that either.

For 'many' read most.