Bonding in commercial catering kitchen

David Stone said:

This sounds like standards "feature creep" of the worst type AGAIN Graham. Definitions not fit for purpose! Earthing of kitchen tables is the worst DANGEROUS idea ever.

I'm sorry you feel that way, David, but the plain fact of the matter is, BS 7671 CANNOT be used to design an appliance like this one: https://www.nisbets.co.uk/hobart-profi-pass-through-dishwasher-amx-10a/fd251

The manufacturer looks at the product standard, does their risk assessments, and decides what is, and what is not, the safest approach.

And we can't simply sit on the sidelines and recommend that any bonding required by the product standards for this kind of product ought to be removed - or not installed in the first place.

There are so many different options of commercial kitchen appliances with built-in, or attachable, work-surfaces, that we cannot simply think about a traditional, stand-alone, "table", "bench" and assume that is all there is to it.

broadgage said:

I agree that earthing of kitchen tables is pointless and could even add to risks.

If a stand-alone metal bench or table is situated between two appliances that have earthed work surfaces, what is the best thing to do?

Accidental contact with one appliance may exacerbate the risk of touch voltage in a fault in another ... in which case definitely safer to bond (and that's where BS EN 60204-1 comes from). And BS 7671 also permits supplementary local equipotential bonding as a measure for additional protection.

broadgage said:

That however counts for nothing if the elfansafety require it. These people are not generally engineers and need some simple rules to follow.

"green and yellow wire to each table============tick.

Blue cable used outdoors====================tick.

Agreed in full ... but that's another problem entirely.

"If a stand-alone metal bench or table is situated between two appliances that have earthed work surfaces, what is the best thing to do?"

Leave things as they are.

Z.

Your link Graham is an example of the kind I was talking about. Have you ever seen a dishwasher like the example? I you had you would know that all the sections are bolted together so no supplementary bonding is required! We are not discussing items like this, we are simply discussing the rest of the work surfaces, which are NOT integrated with electrical equipment. As they have no electrical connections, why do you want to Earth them? They are NOT extraneous conductive parts, like metal window frames, and we do not Earth these do we? There is a complete disconnect between many regulations, those involved are obviously unable to see the problem. We often find questions here where multiple rules collide from differing sources, it is a minefield for the average tradesman.

David Stone said:

I you had you would know that all the sections are bolted together so no supplementary bonding is required!

David, yes, I have seen this kind of appliance.

I also know (which you do not appear to acknowledge) is that bonding is required by the standard, if the appliance is made to BS EN 60204-1. However, to re-quote myself from an earlier post about the bonding  'BUT that could be effected by physically bolting the table to another part of the machine' - the deciding factor in the standard is whether bonding is removed by disconnecting (for repair, replacement or maintenance) another component of the machine.

David Stone said:

We are not discussing items like this, we are simply discussing the rest of the work surfaces, which are NOT integrated with electrical equipment.

Again, as I said earlier, the original post did not specify. You may want to bound this in an arbitrary way ... I'm not satisfied with that, because that dishwasher has "tables" bolted to it.

David Stone said:

We often find questions here where multiple rules collide from differing sources, it is a minefield for the average tradesman.

Sadly, the world isn't always one-syllable.

David Stone said:

They are NOT extraneous conductive parts, like metal window frames, and we do not Earth these do we?

Are you saying window frames are extraneous-conductive-parts ?

I have seen some pretty crowded commercial kitchens in pubs and restaurants. It can sometimes be difficult to easily move around them as they are filled with metal tables, appliances and other necessary equipment that has increased over the years.

Could Section 706 ever apply to such a kitchen?

Z.

Wow!!

Who would have thought a simple (or not so simple) question would get so many answers...

Many thanks to all who have replied....

No  Graham, you have misunderstood, it is an example of some random metal not something likely to introduce a potential!

I think it could Z and often does if everything is given G/Y wires everywhere.

In Noah's time we used to run the bonding cables at the back of tables or other equipment, normally against a wall,  so that they did not get in the way. But after a few bashes with pots and trays they were soon disconnected from their connecting clamps or screws and just left flapping around. It was an 'orrible greasy job installing 'em.

Z.