Earthing a kitchen sink - what size cable?

[Bert Coules]

Hey, I can't help it if I'm a naturally trusting soul.

Anyone want to buy a reel of 16mm2 earth cable?

Bert

[Bert Coules]

Thanks for that. Assuming, of course, that you're not joking.

Bert

[John Rumm]

For the record: Page 26, section 4.6 (refers to regulation 471-08-01)

There is no specific requirements in BS7671 to supplementary bond the following

Kitchen pipes, sinks, or draining boards

metal furniture in kitchens

metal pipes and and wash hand basins in domestic locations other than bathrooms

[BigWallop]

Is there no earth bonding hidden behind kitchen cupboards or even under the floor boards somewhere? The bonding straps could have been placed where the pipework enters the kitchen, rather than being close to the sink itself. Check along the full length of the pipework from the sink to where pipes disappear out of the kitchen.

I would advise testing the bonding, but that is not really going to help to much, so I'll just say then, that it's worth placing a bonding strap on each of the cold and hot pipework, and then on to the sink in the kitchen. You say there are bonding points already on the pipework in the bathroom, so this shows that at least some of the pipes are connected, and it means the kitchen might also be bonded but the earthing straps and hidden somewhere. Time to get the torch out. :-)

[BigWallop]

No really Bert, it means just stripping the insulation off at the point on the cable you're going to connect to the clamp. Cut around the insulation about an inch or so apart, then slit the insulation along the length between the cuts, so the insulation can be pulled apart and lifted off. You then bend the bared section of cable around the screw and insert the screw back in to the earth strap. This way the cable is never cut fully through, and so each point benefits from having the full unbroken cable to every point on the bonding loop.

[Mary Fisher]

We talked over breakfast about this. I hope you're not right or my desk (legs), filing cabinets, birdseed feeders, bed and gardening tools will have to be connected. I'm glad I don't wear jewellery.

Now, about my fillings ...

Mary

[bigcat]

Sparks wrote: NT:

I thought the idea of digging up the floor under every sink to put in earth rods, connecting them with 16mm2, and the evident implied illegality of a sink anywhere but on the ground floor would make it all obvious. As usual I was wrong.

NT

[bigcat]

[Bert Coules]

NT,

You know, thinking about it, I reckon the reason I was taken in is that I have great difficulty in visualising measurements in metric. If you'd told me to use cable that was two-thirds of an inch, I believe I'd have seen the joke straight away. Maybe.

Bert

[Tim Morley]

Better explained than me, I was in a rush! Idea being if one connection comes loose you dont loose the bonding to all parts.

[Joe]

There is absolutely no idea so stupid that a bunch of lawyers won't incorporate it into a law. Not for their own enrichment, *obviously*, but for the safety of the public and especially children.

[Joe]

Nonetheless, kitchen sink bonding is being taught to practicing electricians, probably by NICEIC et al.

A few months ago, I was one of those who asked about this, as I was having a kitchen installed and was told it was a requirement. Having asked here and got opinions from people I trust (!), I said I wasn't interested in having it done. The fitter then said he'd quote a private price, not the official one for the kitchen supply company.

I bought an On Site Guide, and left it laying around. The fitter pointed out it said 2004 and these were new regulations. I confirmed this edition was the one on the IEE website. We left it at that. My wife still wasn't sure I was right.

Eventually the fitter did the work anyway, at no cost, as he said he would not get the work signed off by his visiting inspector if he didn't. He was clearly aware that the work was unnecessary in principle but necessary from the point of view of his getting paid.

Sure enough, when the electrician arrived to check some moved sockets, he looked for the bonding. Prompted by the fitter, he told me it was necessary for safety. One assumes that the 'self-certifying' organisations are pushing this kind of thing to increase profits from the unwary. It doesn't say much for their integrity.

[Lobster]

I doubt it's as nefarious as that, I think it's just ignorance. When I had a sparks round a few months ago to vet a rewiring job of mine, he insisted upon kitchen sink bonding (I'd deliberately not done it); have to say I didn't argue with him. This guy isn't (or at least wasn't, pre-Part P) a NICEIC member - he hates them with a vengeance actually! He didn't charge me any more for coming back to check it later, so it wasn't a profiteering exercise.

David

[Mary Fisher]

Thinking about this, why should there be?

The water pipes which are in contactwith the sink are surely earthed?

Mary

[John Rumm]

Unless the are plastic.... or cocooned in PTFE tape!

[Sparks]

Or maounted in the worktop like mine are!

Sparks...

[Mary Fisher]

Hmm. Hadn't thought about that - never seen it...

Mary

[tony sayer]

In article , Mary Fisher writes

Pardon me sticking me Oar in, but I could have sworn blind that I read on some IEE website somewhere, not that long ago, that it wasn't good practice to earth the kitchen sink.

Something to do with it "might not be a good idea to make a better earth than what otherwise might be" or something like that?.

Course that might be total bollox but If anyone can expand on that....

[Mary Fisher]

Oh please don't do that, they'll expect me to!

Mary

[BigWallop]

(IEE Safety Extract)

Voltage alone doesn't kill; it is different voltages between different parts of the body, and the resulting currents, that can prove injurious or fatal. As earlier, under certain fault conditions, parts of the earthing system in the house may not be at earth potential but significantly above it. The equipotential bonding system is intended to ensure that, if this happens, the voltage between items of equipment at arm's length never reaches a harmful level. Without equipotential bonding, a serious short circuit in the house could cause a significant voltage on the metalwork of an electric kettle while the kitchen tap close to it remained at true earth. Putting an earthing connection, an equipotential bond, between the kitchen sink and the earth terminal of the kitchen ring main prevents that dangerous voltage occurring and ensures that the tap is at the same voltage as the body of the kettle.

There are two aspects to the equipotential bonding; the main bonding where services enter the building and supplementary bonding within rooms, particularly kitchens and bathrooms. Main bonding should interconnect the incoming gas, water and electricity service where these are metallic but can be omitted where the services are run in plastic, as is frequently the case nowadays. Internally, bonding should link any items which are likely to either be at earth potential or which may become live in the event of a fault and which are either gripable or sufficiently large that they can contact a significant part of the body. Small parts, other than those likely to be gripped, are ignored because the instinctive reaction to a shock is muscular contraction, which will break the circuit.