sink earthing

kramer1

Does my sink need to be earthed if theres only plastic pipes connected to it? And if so what size cable should I use?
And do I have to run it back to the consumer unit or can I just take it from the socket below?

M cebee

kramer1 wrote: »

Does my sink need to be earthed if theres only plastic pipes connected to it? And if so what size cable should I use?
And do I have to run it back to the consumer unit or can I just take it from the socket below?

they're connected to a local protective conductor ie:socket in 2.5 earth

the rule says 'extraneous conductive parts in utilitys and kitchens'
- to me that suggests you could test it if it's fed in plastic to see is it actually extraneous
-above 22k ohm to MET or thereabouts and it's not
- but i doubt many do it

meercat

kramer1 wrote: »

Does my sink need to be earthed if theres only plastic pipes connected to it? And if so what size cable should I use?
And do I have to run it back to the consumer unit or can I just take it from the socket below?

the sink itself must be earthed
as m cebee says ,a 2.5 earth from a local socket should suffice
there are earth tags (radiator tags)available that clamp the sink underneath if no bond link fitted on your sink(awkward as hell to fit though)

M cebee

meercat wrote: »

the sink itself must be earthed
as m cebee says ,a 2.5 earth from a local socket should suffice
there are earth tags (radiator tags)available that clamp the sink underneath if no bond link fitted on your sink(awkward as hell to fit though)

'must' it be bonded here though
if it's not extraneous when tested
not according to my reading of rules

meercat

M cebee wrote: »

'must' it be earthed here though
if it's not extraneous

cant see any reason not too

M cebee

meercat wrote: »

cant see any reason not too

yes prob as well anyhow
it may get earthed through a pipe or anything later

Bruthal

Not the easiest things to earth at times

M cebee

robbie7730 wrote: »

Not the easiest things to earth at times

pain the ass since they stopped fitting tags
usually get it with the rad clamp

Max_Charger

If the clamp fails then a trusty small wood screw into the side of the worktop with the wire well crimped on a lug, and a small prayer to go with it that it doesn't go through the top of the counter...Blood, sweat and tears have gone into earthing sinks in the past...

M cebee

Max_Charger wrote: »

If the clamp fails then a trusty small wood screw into the side of the worktop with the wire well crimped on a lug, and a small prayer to go with it that it doesn't go through the top of the counter...Blood, sweat and tears have gone into earthing sinks in the past...

would it pass an inspection?
dont think so

Max_Charger

M cebee wrote: »

would it pass an inspection?
dont think so

Only to be used as an absolute last resort but never had problems with inspections so long as its a solid connection.

2011

M cebee wrote: »

would it pass an inspection?
dont think so

Why not? Once it can be demonstrated that it provides a secure and strong low resistant joint. It would not be hard to measure the resistance of the connection.

I would think that a self tapping screw would be preferable or better again a nut and bolt.

Bruthal

2011 wrote: »

Why not? Once it can be demonstrated that it provides a secure and strong low resistant joint. It would not be hard to measure the resistance of the connection.

I would think that a self tapping screw would be preferable or better again a nut and bolt.

A few strands just touching will give as low a reading or very close to it, as a proper bolt through hole, or rad clamp earth will. So a low reading is no guarantee of a good quality connection.

M cebee

2011 wrote: »

Why not? Once it can be demonstrated that it provides a secure and strong low resistant joint. It would not be hard to measure the resistance of the connection.

I would think that a self tapping screw would be preferable or better again a nut and bolt.

-the method of connection is a separate issue to the 'resistance' which is usually low regardless(initially)

-not sure self-tappers and woodscrews are allowed for bonding

how could a self tapper be better than a nut and bolt?

Bruthal

M cebee wrote: »

-the method of connection is a separate issue to the 'resistance' which is usually low regardless(initially)

Id agree with that. Similar to what I was saying in last post. Low resistance is no guarantee of a good connection.

Depending on another completely separate material or item to maintain a good contact on a metal object cant be great.

Max_Charger

2011 wrote: »

Why not? Once it can be demonstrated that it provides a secure and strong low resistant joint. It would not be hard to measure the resistance of the connection.

I would think that a self tapping screw would be preferable or better again a nut and bolt.

Self tapping screws are what we use for bonding large stainless-steel commercial kitchen units in pubs, restaurants etc and never had a problem with inspections.

M cebee

Max_Charger wrote: »

Self tapping screws are what we use for bonding large stainless-steel commercial kitchen units in pubs, restaurants etc and never had a problem with inspections.

don't get me wrong
trying to bond these sinks is torture and i've used the pozi into the worktop method as a last resort meself

not sure if the pozi or screw complies with et101 for local bonding
i'd say it's more a case of inspectors turning a blind eye
-maybe it does?

meercat

M cebee wrote: »

i'd say it's more a case of inspectors turning a blind eye

i think most inspectors realize how difficult it is to get a tag on

2011

M cebee wrote: »

how could a self tapper be better than a nut and bolt?

You have misread my post, I said:

I would think that a self tapping screw would be preferable or better again a nut and bolt.

M cebee

2011 wrote: »

You have misread my post, I said:

2011

robbie7730 wrote: »

A few strands just touching will give as low a reading or very close to it, as a proper bolt through hole, or rad clamp earth will.

As I said I my preference would be for a nut and bolt (assuming that a suitable termination point is simply not available).

However I feel that if this was not possible that a self tapper would suffice and in keeping with good practice it would be best to use a cable lug was used. This would provide a reasonable surface area for a 2.5 sq. mm cable. Once it can be demonstrated that it provides a secure and strong low resistant joint.

So a low reading is no guarantee of a good quality connection.

I think that it is important to look at the purpose of equipotential bonding.
As you know, it is to keep simultaneously accessible conductive parts at the same potential.
I do not see why this can not be achieved with a self tapper.

If it can be shown:

1) All conductive parts are connected together using the correct size and type cable.
2) All terminations are tight secure.
3) The resistance measured between all simultaneously accessible conductive parts is negligible.
4) Proper earth termination points are used where available/possible.

In my view an inspector would be satisfied in the above case if a self tapper (and cable lug) combination was used to bond a kitchen sink.

In fact I have only ever seen metal pipe cladding cross bonded in this way.

Bruthal

2011 wrote: »

As I said I my preference would be for a nut and bolt (assuming that a suitable termination point is simply not available).

However I feel that if this was not possible that a self tapper would suffice and in keeping with good practice it would be best to use a cable lug was used. This would provide a reasonable surface area for a 2.5 sq. mm cable. Once it can be demonstrated that it provides a secure and strong low resistant joint.



I think that it is important to look at the purpose of equipotential bonding.
As you know, it is to keep simultaneously accessible conductive parts at the same potential.
I do not see why this can not be achieved with a self tapper.

If it can be shown:

1) All conductive parts are connected together using the correct size and type cable.
2) All terminations are tight secure.
3) The resistance measured between all simultaneously accessible conductive parts is negligible.
4) Proper earth termination points are used where available/possible.

In my view an inspector would be satisfied in the above case if a self tapper (and cable lug) combination was used to bond a kitchen sink.

In fact I have only ever seen metal pipe cladding bonded in this way.

I didnt dispute any of that, just that testing an earth connection and getting a low ohm reading, does little to show its a good quality connection.

A screw into wood, to hold a lug against a sink, will show a good enough reading. But its not great to depend on the mechanics of wood and screw to hold a lug against a sink.

Im not in anyway having a go at max_charger`s point about that. Some of them sinks are horrendous to get at.

2011

robbie7730 wrote: »

A screw into wood, to hold a lug against a sink, will show a good enough reading. But its not great to depend on the mechanics of wood and screw to hold a lug against a sink.

This is why I suggested a self tapper rather than a wood screw.

Im not in anyway having a go at max_charger`s point about that. Some of them sinks are horrendous to get at.

True.