BONDING METAL WORKTOPS

[Jonny72]

I thought an exposed conductive part would need to be earthed, not bonded.

If an exposed conductive part, it requires earthing.
Is an extraneous conductive part, it requires bonding.
If neither of the above, it requires neither earthing nor bonding

Blame me for the mix up - I am learning. I take it using the pipework which has a good earth would be out of the question? Risk of plumbers replacing copper with plastic at some stage??

 

[Julie.]

I thought an exposed conductive part would need to be earthed, not bonded.

If an exposed conductive part, it requires earthing.
Is an extraneous conductive part, it requires bonding.
If neither of the above, it requires neither earthing nor bonding

So I looked it up whilst waiting for the football to start (yawn).

415.2.1 covers supplementary bonding of exposed conductive parts, indicating that exposed conductive parts must be connected to both extraneous conductive parts (if simultaneously accessible) and the protective conductor of equipment and socket outlets.


Basically if you're bonding the extraneous conductive parts at the incomer this is the main protective bonding.
If you are earthing the exposed conductive parts of a piece of equipment, that's earthing.

If you are bonding multiple pieces of equipment's exposed conductive parts and/or anything else, that's supplementary bonding.

 

[Jonny72]

So I looked it up whilst waiting for the football to start (yawn).

415.2.1 covers supplementary bonding of exposed conductive parts, indicating that exposed conductive parts must be connected to both extraneous conductive parts (if simultaneously accessible) and the protective conductor of equipment and socket outlets.


Basically if you're bonding the extraneous conductive parts at the incomer this is the main protective bonding.
If you are earthing the exposed conductive parts of a piece of equipment, that's earthing.

If you are bonding multiple pieces of equipment's exposed conductive parts and/or anything else, that's supplementary bonding.

Lol so from 18th edition these metal worktops are counted as exposed conductive parts (although not equipment but some have equipment on them) and so should be earthed. And from you.... better to take the earth from the MET on the DB. Could in reality connect a earth bonding clip to each leg underneath to ensure all 6 are adequately earthed.

 

[mainline]

Lol so from 18th edition these metal worktops are counted as exposed conductive parts (although not equipment but some have equipment on them) and so should be earthed. And from you.... better to take the earth from the MET on the DB. Could in reality connect a earth bonding clip to each leg underneath to ensure all 6 are adequately earthed.

If none of these metal tables etc are not connected to any earth (you said you tested) then they don't need bonding

 

[Jonny72]

If none of these metal tables etc are not connected to any earth (you said you tested) then they don't need bonding

Wish I had a pic Mainline. Two are metal tables which havent moved in 20 years. The other metal tops are connected to fabric of the building ie filed in. Yea there is no earth on ANYTHING!!!!! Am I getting bonding and earthing mixed up????

 

[Jonny72]

Wish I had a pic Mainline. Two are metal tables which havent moved in 20 years. The other metal tops are connected to fabric of the building ie filed in. Yea there is no earth on ANYTHING!!!!! Am I getting bonding and earthing mixed up????

I know bonding ensures everything is at the same potential. Earthing ensures a conductive path to ground

 

[Julie.]

Lol so from 18th edition these metal worktops are counted as exposed conductive parts (although not equipment but some have equipment on them) and so should be earthed. And from you.... better to take the earth from the MET on the DB. Could in reality connect a earth bonding clip to each leg underneath to ensure all 6 are adequately earthed.

Metal is just that, it doesn't make it an exposed conductive part, it only becomes an exposed conductive part if there is a possibility of a live conductor (due to a fault of some type) making it live.

So a random metal worktop would not require any bonding or earthing.

However if the worktop arrangement or use makes it possible; then it needs supplementary bonding.

It is not clear cut.

In general if you have fixed metal worktops, and electrical equipment on them in a commercial kitchen environment, I would consider it needs bonding.

What would happen if trailing leads for kitchen tools got damaged and came in contact with the metal worktop? In general the way most commercial kitchens end up, I would bond.

But there is no absolute requirement.

 

[Jonny72]

Metal is just that, it doesn't make it an exposed conductive part, it only becomes an exposed conductive part if there is a possibility of a live conductor (due to a fault of some type) making it live.

So a random metal worktop would not require any bonding or earthing.

However if the worktop arrangement or use makes it possible; then it needs supplementary bonding.

It is not clear cut.

In general if you have fixed metal worktops, and electrical equipment on them in a commercial kitchen environment, I would consider it needs bonding.

What would happen if trailing leads for kitchen tools got damaged and came in contact with the metal worktop? In general the way most commercial kitchens end up, I would bond.

But there is no absolute requirement.

Yea that's kinda my intuition Julie particularly with the trailing wires and faulty equipment I found. Saving grace- They have RCBO. I could run earth from the DB Met to the kitchen and connect to the leg of each metal bench. Parts of them are tiled in so could not be deemed movable. What is you thought process on not using the copper pipes?? Insufficient earth or risk from plumbers breaking conductive part with plastic pipe?

 

[Julie.]

I always run the balance between options.

Option 1 - supplementary bonding in accordance with 415.2.1

If there is a fault of poor cabling etc contacting the worktop and the person with wet hands, there is a big bang, no current goes through the person to speak of , no one dies, you don't go to court.

Option 2 - it's not mandatory to bond so no bond.

If there is a fault of poor cabling etc contacting the worktop and the person with wet hands, the current goes through the person, even though the rcbo trips (or perhaps fails to) the shock is still sufficient to cause serious injury or death, you go to court, but can prove you did comply with the minimum requirements, so would likely be able to fend off any charges etc.

That's my reasoning! I would prefer the former rather than the latter.

As for the Connections, take a look at 415.2.1, it makes it fairly clear what is suitable.

I would bond between pipes, tables and the earth/cpc points of the socket outlets all locally.

 

[mainline]

I always run the balance between options.

Option 1 - supplementary bonding in accordance with 415.2.1

If there is a fault of poor cabling etc contacting the worktop and the person with wet hands, there is a big bang, no current goes through the person to speak of , no one dies, you don't go to court.

Option 2 - it's not mandatory to bond so no bond.

If there is a fault of poor cabling etc contacting the worktop and the person with wet hands, the current goes through the person, even though the rcbo trips (or perhaps fails to) the shock is still sufficient to cause serious injury or death, you go to court, but can prove you did comply with the minimum requirements, so would likely be able to fend off any charges etc.

That's my reasoning! I would prefer the former rather than the latter.

As for the Connections, take a look at 415.2.1, it makes it fairly clear what is suitable.

I would bond between pipes, tables and the earth/cpc points of the socket outlets all locally.

We must also remember that items that weren't required to be bonded in certain faults can also be dangerous.
Coming into contact with a live conductor and that now earthed table is going to hurt.