BONDING METAL WORKTOPS

[Jonny72]

Kitchen in Care home. All metal surfaces. No bonding and no earth on test. RCBOs in DB. Does this still need bonding????

 

[mainline]

Sorry new. Realise may be in wrong thread. Sorry

If It's not likely to bring in an earth from outside (extraneous) then no.

 

[Jonny72]

If It's not likely to bring in an earth from outside (extraneous) then no.

Thanks. All surfaces are metal so exposed and conductive. They could become live under fault conditions say a wire in piece of kitchen equipment was torn. So I would say yes extraneous.There are supply copper pipes in the kitchen which are bonded. Was thinking cud fit to them.

 

[mainline]

Thanks. All surfaces are metal so exposed and conductive. They could become live under fault conditions say a wire in piece of kitchen equipment was torn. So I would say yes extraneous.There are supply copper pipes in the kitchen which are bonded. Was thinking cud fit to them.

So could a metal chair or a knife.

 

[James]

I would say no, bonding not required.

Also, are they not movable counters, most commercial kitchens the work tops can be moved to help with cleaning down etc.
so therefore being mobile how would you attach wires to them?

 

[Jonny72]

So could a metal chair or a knife.

They are fxed in place unlike metal chair or fork so get ur point I know prob a silly question bit I have seen other kitchens bonded like hell. Maybe old regs. Was thinking that the RCBOs may be aqauate anyways.

 

[Julie.]

These would most certainly NOT be extraneous conductive parts.

Unless the kitchen surfaces themselves extend externally and to the ground itself.

However I would consider them an extension of exposed conductive parts, and require supplementary bonding.

But it very much depends on circumstances, movable tables no, but if it is a complete kitchen fitted worktop with appliances resting on or adjacent to it I would add supplementary

 

[Jonny72]

These would most certainly NOT be extraneous conductive parts.

Unless the kitchen surfaces themselves extend externally and to the ground itself.

However I would consider them an extension of exposed conductive parts, and require supplementary bonding.

But it very much depends on circumstances, movable tables no, but if it is a complete kitchen fitted worktop with appliances resting on or adjacent to it I would add supplementary

Julie that is great. Getting my head around meaning of extraneous. Some of the worktops are built in and others movable but have not been moved in 20 years. There is fixed equipment on the tops. There is pipework which has good bonding. Was considering connecting to this pipework as the DB is 25m away. I did a PAT last month and the the condition of some of the equipment was awful. Failed 3 items. Not a good environment for a metal surface.

 

[Julie.]

Julie that is great. Getting my head around meaning of extraneous. Some of the worktops are built in and others movable but have not been moved in 20 years. There is fixed equipment on the tops. There is pipework which has good bonding. Was considering connecting to this pipework as the DB is 25m away. I did a PAT last month and the the condition of some of the equipment was awful. Failed 3 items. Not a good environment for a metal surface.

Bonding is covered in 415.xx I am not sure just picking up a connection from pipework is suitable.

 

[mainline]

These would most certainly NOT be extraneous conductive parts.

Unless the kitchen surfaces themselves extend externally and to the ground itself.

However I would consider them an extension of exposed conductive parts, and require supplementary bonding.

But it very much depends on circumstances, movable tables no, but if it is a complete kitchen fitted worktop with appliances resting on or adjacent to it I would add supplementary

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

 

[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.

 

[mainline]

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.

Maybe a better idea would be to try to ensure that the cables etc are protected.

 

[Jonny72]

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.

Julie thanks. Used to 'spark' Airframes lol - bonding on aircraft more for lightening strike potential. Can understand bonding between pipes and cables but CPCs of outlets sockets. Never seen this!!! This a matter of just tapping and earth from the socket??? All the sockets??? Can understand Mainlines point too. It would be fairly easy to run a 10mm cable from the DB put may be 20m length in 10mm conduit from the outside but obviously the sockets will only provide 1mm as lightly on 2.5mm ring. Really appreciate all u guys help as although I have plenty of Quals, installation is fairly new to me. I will have read of 415.2.1 but find IET Genuinely thanks so far. I am learning.

 

[GBDamo]

Maybe a better idea would be to try to ensure that the cables etc are protected.

Isn't this why we have additional protection it the form of RCDs?

What is bonding going to achieve?

It's going to introduce an alternative, low resistance, earth path.

Take, for example, a hand held blender. You're stood holding it and a metal mixing bowl on our metal worktop. There is a fault to the casing of the blender.

With RCD only protection you'd have a <30ms trip and a very minor electric shock.

With RCD and Bonding would the low resistance earth path allow for a larger shock whilst still tripping in <30ms?

With no RCD relying on Bonding only, your getting a right belt, but hopefully our circuits are well designed and OPCDs correctly selected and we get a <0.4 second frying.

With no RCD and no Bonding our face slowly melts, like the ---- (Wow, we can't refer to the goose stepping, dapper krauts) in Indiana Jones and the Raiders of the Lost Ark, as nobody bats an eyelid as the smell of burning meat eminantes from the kitchen.


So, are the bonding fetishists suggesting we bond to mitigate a failure of the RCD.

Where does that stop? Two I dependant bondings in case one fails?

Belt, braces, elasticated wasteband and a little person with a modesty curtain.

 

[Jonny72]

Isn't this why we have additional protection it the form of RCDs?

What is bonding going to achieve?

It's going to introduce an alternative, low resistance, earth path.

Take, for example, a hand held blender. You're stood holding it and a metal mixing bowl on our metal worktop. There is a fault to the casing of the blender.

With RCD only protection you'd have a <30ms trip and a very minor electric shock.

With RCD and Bonding would the low resistance earth path allow for a larger shock whilst still tripping in <30ms?

With no RCD relying on Bonding only, your getting a right belt, but hopefully our circuits are well designed and OPCDs correctly selected and we get a <0.4 second frying.

With no RCD and no Bonding our face slowly melts, like the ---- in Indiana Jones and the Raiders of the Lost Ark, as nobody bats an eyelid as the smell of burning meat eminantes from the kitchen.


So, are the bonding fetishists suggesting we bond to mitigate a failure of the RCD.

Where does that stop? Two I dependant bondings in case one fails?

Belt, braces, elasticated wasteband and a little person with a modesty curtain.

There are RCBOs in the DB. Yea I may be one of those ppl with a earthing fetish sorry. I suppose only fear is the RCBO may not trip and earth connection is 'good old faithful'. I saw a kitchen recently similar which had earth connections every metal surface but may have been done 15 years ago when earthing and bonding was a bit mental. Would RCD sockets in the areas of risk be sensible or is this just going to bring an issue and be nonsensical with RCBOs in DB 20m away? Maybe local RCB Think protecting the cables may be an idea too. Seriously what I found in there during a PAT would curl your hair . That's what brought about my concern. Be nice - I am learning

 

[littlespark]

We don’t bond every lump of metal in a domestic kitchen…. Dishwashers, ovens etc… we rely on the earth wire it came with…. And this is where a fault in itself could happen…. Not from another appliance.

If it was all to be bonded, there would be a section for commercial kitchens under “special locations” like there is with swimming pools.

The RCD protection does away with bonding in most other cases, on the assumption they are tested regularly and replaced if faulty.

 

[mainline]

There are RCBOs in the DB. Yea I may be one of those ppl with a earthing fetish sorry. I suppose only fear is the RCBO may not trip and earth connection is 'good old faithful'. I saw a kitchen recently similar which had earth connections every metal surface but may have been done 15 years ago when earthing and bonding was a bit mental. Would RCD sockets in the areas of risk be sensible or is this just going to bring an issue and be nonsensical with RCBOs in DB 20m away? Maybe local RCB Think protecting the cables may be an idea too. Seriously what I found in there during a PAT would curl your hair . That's what brought about my concern. Be nice - I am learning

What are the chances that a live conductor is going to come in contact with the metal table ? I would say very unlikely.

If this unlikely event did happen, the person touching the now live table would have to be standing on a very earthy floor with wet hands in bare feet to receive anything substantial also if the floor is that earthy the table would also be.

Is the supply PME ? As something that maybe worth considering is a PEN fault that could cause all your now earthy metal to go live and your rcbo isn't going to help at all.

 

[newfutile]

You have to determine if it’s and extraneous conductive part. This can be as acheived by an IR test from the metalwork to the MET , I always 10 ma current therefore 23 KiloOhms or less makes it an en extraneous conductive part

 

[mainline]

You have to determine if it’s and extraneous conductive part. This can be as acheived by an IR test from the metalwork to the MET , I always 10 ma current therefore 23 KiloOhms or less makes it an en extraneous conductive part

He said that he has tested and there is no earth to any of it.

 

[Jonny72]

You have to determine if it’s and extraneous conductive part. This can be as acheived by an IR test from the metalwork to the MET , I always 10 ma current therefore 23 KiloOhms or less makes it an en extraneous conductive part

Yes I did that. I tested between earth on a socket and all benches. Was open circuit and I used Dilog MFT.

 

[Julie.]

There is no way I would suggest that we bond all random bits of metal, in fact this never was a requirement, and the old interpretation many followed of doing something like that was as incorrect then as it is now (even though it ended up in guidelines and other supportingdocuments).

However there are circumstances where it is beneficial to bond metallic material where a particular risk may exist.

The regs actually assign a name to this (supplementary bonding), and detail how it needs to be done.

Indeed if we just take the minimum requirement from the regs as all that should be done, then the whole definition and detail of supplementary bonding needs to be removed from the regs.

The reason it is there is for circumstances such as this (in my opinion), but in doing so it doesn't follow that "by the same thought everything needs to be bonded" or similar arguments.