Bathroom refit, do I need a RCD?

[timhoward]

Hi again Tim, when I get it tested, how does the tester assess the supplementary bonding? If it is by inspection should I remove the bath panel so that they can see the pipes?

No, I wouldn't remove the panel (oh that all home owners would think in such an obliging way!)

A lot of installations would meet the 3 requirements in section 701 (automatic disconnection of supply for all circuits in room, RCD protection for all circuits in room, and all extraneous conductive parts are bonded) which would mean supplementary bonding isn't required.
You don't have RCD protection for all circuits in room, so be default supplementary bonding is required.
So next question is are there any metallic parts that could introduce a potential in the bathroom (extraneous conductive parts).
If there are then the CPC of all circuits in the room need to be connected to the extraneous conductive parts with supplementary bonding.

From what you've said it sounds as though the copper pipe to the toilet cistern might be a contender.
You haven't mentioned any heating in there - is the a radiator / towel rail with metal pipes?

Having determined that supp. bonding is required, and there are items that require it, it's usually quickest to use continuity tests to check the resistance between the items is low enough to keep the touch voltage below 50v. There's a formula in the regs for how low it needs to be.

 

[Johnstar]

No, I wouldn't remove the panel (oh that all home owners would think in such an obliging way!)

A lot of installations would meet the 3 requirements in section 701 (automatic disconnection of supply for all circuits in room, RCD protection for all circuits in room, and all extraneous conductive parts are bonded) which would mean supplementary bonding isn't required.
You don't have RCD protection for all circuits in room, so be default supplementary bonding is required.
So next question is are there any metallic parts that could introduce a potential in the bathroom (extraneous conductive parts).
If there are then the CPC of all circuits in the room need to be connected to the extraneous conductive parts with supplementary bonding.

From what you've said it sounds as though the copper pipe to the toilet cistern might be a contender.
You haven't mentioned any heating in there - is the a radiator / towel rail with metal pipes?

Having determined that supp. bonding is required, and there are items that require it, it's usually quickest to use continuity tests to check the resistance between the items is low enough to keep the touch voltage below 50v. There's a formula in the regs for how low it needs to be.

Lovely reply Tim,
So yes the pipe to the toilet cistern is copper and extraneous, it is bonded with a strap and earth cable running back to the CU main earth block. The other parts that introduce potential are the fan isolation switch and the shaver socket both with metal back boxes connected to the protective conductor. The one central light also has a metal case and I will replace this with a modern plastic one. All of these are in the Outside Zone. The light switch is outside the room.
There is no heating in the room and no other metal parts entering from outside.
With the resistance test, if they were to check the taps, they would be open circuit due to the plastic pipes, how would they know the difference between a failed bonding test and plastic pipe?

 

[swaRRR]

Yes. Domestic installs now all circuits require RCD protection if i remember rightly. Would have to check regs to be 100% but as far as i remember you're only allowed to not have RCD protection in commercial premises and only when the appropriate risk assessments have been done to justify not having it.

 

[Johnstar]

Yes. Domestic installs now all circuits require RCD protection if i remember rightly. Would have to check regs to be 100% but as far as i remember you're only allowed to not have RCD protection in commercial premises and only when the appropriate risk assessments have been done to justify not having it.

Hi,
Thanks this was also pointed out by Westwood so I have decided to leave the electrics alone and just change the light fitting to a modern one. I did fancy downlights but it’s going to be too expensive if I have to fit an RCD.

So now the question is, can I pass a EICR as it stands with the original consumer units and no RCD?

 

[timhoward]

So yes the pipe to the toilet cistern is copper and extraneous, it is bonded with a strap and earth cable running back to the CU main earth block.

Good stuff, though are you 100% sure that is where it goes? (The fact there is bonding in this location at all suggests someone has already considered this topic and it is supplementary bonding that links up to other accessories in the room.)
The idea is that you can't touch a faulting accessory (e.g. shaver socket) and path to earth without both things being held at the same potential via a direct link of low resistance.

With the resistance test, if they were to check the taps, they would be open circuit due to the plastic pipes, how would they know the difference between a failed bonding test and plastic pipe?

Well to be extraneous it has to leave the room, so first you try and test to somewhere handy just outside e.g an airing cupboard or sometimes a combi boiler. If it's testing open circuit it's reasonable to assume they are plastic pipes or there's an insulated joint in the middle.
If it's low-ish, then you test from the tap to a cpc in the room, and you then find out whether you are looking at the resistance of a fairly short length of bonding cable, OR a larger resistance representing the total path along the pipe, via the main bonding, to the MET, back to the consumer unit and along the CPC of the circuit.
You need an accurate continuity tester (or multi function tester) to do this, multimeters are usually not accurate enough.

We have gone down a slight rabbit hole here - it's a much better use of effort to get the CU upgraded so the complexities of this topic can be brushed aside!

So now the question is, can I pass a EICR as it stands with the original consumer units and no RCD?

I'm not trying to be pedantic, but EICR's aren't pass or fail, you get a report with C1 (dangerous), C2 (potentially dangerous), C3 (improvement recommended).
If rented out C1's and C2's are supposed to be rectified within a fixed time frame (which I forget tonight - 2 weeks?).
If privately owned, you ignore C2's and above at your own peril!

Yes, it is possible to only have C3's in your situation.
It's still a flipping good idea to have RCD protection though!

 

[westward10]

Yes. Domestic installs now all circuits require RCD protection if i remember rightly. Would have to check regs to be 100% but as far as i remember you're only allowed to not have RCD protection in commercial premises and only when the appropriate risk assessments have been done to justify not having it.

This is not correct.

 

[Johnstar]

Good stuff, though are you 100% sure that is where it goes? (The fact there is bonding in this location at all suggests someone has already considered this topic and it is supplementary bonding that links up to other accessories in the room.)
The idea is that you can't touch a faulting accessory (e.g. shaver socket) and path to earth without both things being held at the same potential via a direct link of low resistance.

Well to be extraneous it has to leave the room, so first you try and test to somewhere handy just outside e.g an airing cupboard or sometimes a combi boiler. If it's testing open circuit it's reasonable to assume they are plastic pipes or there's an insulated joint in the middle.
If it's low-ish, then you test from the tap to a cpc in the room, and you then find out whether you are looking at the resistance of a fairly short length of bonding cable, OR a larger resistance representing the total path along the pipe, via the main bonding, to the MET, back to the consumer unit and along the CPC of the circuit.
You need an accurate continuity tester (or multi function tester) to do this, multimeters are usually not accurate enough.

We have gone down a slight rabbit hole here - it's a much better use of effort to get the CU upgraded so the complexities of this topic can be brushed aside!

I'm not trying to be pedantic, but EICR's aren't pass or fail, you get a report with C1 (dangerous), C2 (potentially dangerous), C3 (improvement recommended).
If rented out C1's and C2's are supposed to be rectified within a fixed time frame (which I forget tonight - 2 weeks?).
If privately owned, you ignore C2's and above at your own peril!

Yes, it is possible to only have C3's in your situation.
It's still a flipping good idea to have RCD protection though!

Thanks once again for a great reply.
First point is yes, I’m absolutely sure because I stripped out (cut off) the old copper pipes as they were 15 mm copper sunk into the concrete floor with no insulation or protection of any kind. As I was replacing the old fortic cylinder with a mains pressure one I didn’t trust the old pipes. I’ve run the new pipes from the new cylinder in plastic up and through the loft. Plastic for lower heat loss and ease of run. The old pipes were bonded and connected to the earth block via a thick cable that runs up to the loft and down to the earth block next the CUs.

It’s very difficult to see how you could get a shock in this room as there is simply very little in there and very little exposed at earth potential, the very short pipe to the cistern, and the 4 screw heads for the fan switch and shaver socket.

I agree completely that an RCD would be best and safer but changing the two consumer units is an expense I can’t afford at the moment with everything else going on. Should I rent it in the future I will however change the CUs.

Thanks for the information about the EICR and testing I didn’t know that about the fault classifications.
I remember using a Mega when testing for earth continuity on industrial equipment, it used a much higher current than a standard multimeter and could measure very low resistances. I guess there is an equivalent that you guys use for this work.

Thank you very much Tim this has made things much clearer for me.
Cheers

 

[davesparks]

Yes. Domestic installs now all circuits require RCD protection if i remember rightly. Would have to check regs to be 100% but as far as i remember you're only allowed to not have RCD protection in commercial premises and only when the appropriate risk assessments have been done to justify not having it.

Utter nonsense!

 

[HappyHippyDad]

No they are SB6000. They did make rcbos for them but were two module and would now be second hand. Finding one for a 6 or 10A lighting circuit is likely to be difficult. It is likely they never existed.

I remember looking for a 6A one a few years back. I found a few 32A and 16A but never any other rated ones.

 

[davesparks]

I remember looking for a 6A one a few years back. I found a few 32A and 16A but never any other rated ones.

That's not surprising, in those days the use of RCBO's was much like the current situation with AFDDs. Most people didn't see the need for them, some people did fit them but only when absolutely necessary and that would almost exclusively be socket circuits hence 32A being the most commonly available 2nd hand.