Equipment understairs.

[Edward67]

Ok understairs we need metal as we know. We need metal everywhere in domestic properties.
My question relates to a DNO installed plastic isolator with inbuilt spd under stairs next to my nice new metal consumer unit.
Are they allowed. If its deemed dno equipment then I know they have different rules. The question is though who installed it as its existing the house wiring was very old and I have never seen dno fit a plastic wylex 100a surge projected isolator before as they cost about 120 pounds.
What are your thoughts? Get removed and fit metal one or just accept.
I didnt fit surge protection to my board because of this isolator but in hindsight thinking maybe I should.
I would like genuine discussion and ideally not to drift onto whether we actually need surge protection in a tncs property in rural area.
All thoughts welcome.
Thankyou.

 

[Dartlec]

Ok understairs we need metal as we know. We need metal everywhere in domestic properties.
My question relates to a DNO installed plastic isolator with inbuilt spd under stairs next to my nice new metal consumer unit.
Are they allowed. If its deemed dno equipment then I know they have different rules. The question is though who installed it as its existing the house wiring was very old and I have never seen dno fit a plastic wylex 100a surge projected isolator before as they cost about 120 pounds.
What are your thoughts? Get removed and fit metal one or just accept.
I didnt fit surge protection to my board because of this isolator but in hindsight thinking maybe I should.
I would like genuine discussion and ideally not to drift onto whether we actually need surge protection in a tncs property in rural area.
All thoughts welcome.
Thankyou.

Is it the Wylex one?

Whether it is compliant now to install under BS7671 presumably comes down to whether it counts as 'consumer unit and similar switchgear assemblies'.

According to the data sheet it does come under the BSEN 60947-3 standard , which might suggest it is covered, but I've not seen anything definitive. The data sheet on the link above still references BS7671:2008 so not sure it can be relied upon as current. It also only mentions TN-S and TT under 'protective system', but not sure that is any comment on its suitability in TN-C-S cases.

Do you know the main fuse rating? There have been changes with SPD installation guidance where most manufacturers have now decided that they need their own protection, not just the main fuse - though this one seems to suggest it is acceptable if it is less than 80A when wired as an isolator.

If it's already in place personally I'd see no issue with keeping it - the guidance is very clear that a plastic consumer unit should not be automatically replaced on sight, assuming there are no signs of damage, etc so that would apply even if this was not "18th edition" compliant.

On an EICR plastic CUs are recommended as a C3 only if under wooden stairs or in a sole escape route, but otherwise need not be commented on. (Unless unsatisfactory connections are found of course).

As you say seems unlikely that the DNO installed it on their own cost, though it's possible that it was installed by them but paid for by the homeowner for some reason?

I honestly don't see any need to upgrade it to a metal one unless there is a specific concern in your particular case.

 

[Edward67]

Is it the Wylex one?

Whether it is compliant now to install under BS7671 presumably comes down to whether it counts as 'consumer unit and similar switchgear assemblies'.

According to the data sheet it does come under the BSEN 60947-3 standard , which might suggest it is covered, but I've not seen anything definitive. The data sheet on the link above still references BS7671:2008 so not sure it can be relied upon as current. It also only mentions TN-S and TT under 'protective system', but not sure that is any comment on its suitability in TN-C-S cases.

Do you know the main fuse rating? There have been changes with SPD installation guidance where most manufacturers have now decided that they need their own protection, not just the main fuse - though this one seems to suggest it is acceptable if it is less than 80A when wired as an isolator.

If it's already in place personally I'd see no issue with keeping it - the guidance is very clear that a plastic consumer unit should not be automatically replaced on sight, assuming there are no signs of damage, etc so that would apply even if this was not "18th edition" compliant.

On an EICR plastic CUs are recommended as a C3 only if under wooden stairs or in a sole escape route, but otherwise need not be commented on. (Unless unsatisfactory connections are found of course).

As you say seems unlikely that the DNO installed it on their own cost, though it's possible that it was installed by them but paid for by the homeowner for some reason?

I honestly don't see any need to upgrade it to a metal one unless there is a specific concern in your particular case.

Thanks for reply. Dartlec
I have looked at the data sheet and the issue I have is as you say TNCS is not mentioned so is it suitable?
I might contact Wylex directly. To ask the question.
The main fuse I believe is 80amp to to be 100 percent would need to have fuse pulled.

 

[Wilko]

Hi - are you sure the SPM has been installed by a DNO (?) as the location after the meter is part of the Installation, not the Network.

For what it’s worth, inside a house under the timber stairs I would only use metal as per the CU.
[automerge]1601926555[/automerge]

It also only mentions TN-S and TT under 'protective system', but not sure that is any comment on its suitability in TN-C-S cases.

Hi - as far as I know this SPM is suitable for most earthing systems, I don’t know why that doc doesn’t show it. Here’s a screen shot from another site of perhaps a later spec sheet and it’s got them all listed.

 

[Dartlec]

That makes more sense - also seems to suggest that 125A main fuse is an acceptable backup, although other manufacturers seem to have gone to requiring it's own MCB of 32A.

 

[Edward67]

Hi - are you sure the SPM has been installed by a DNO (?) as the location after the meter is part of the Installation, not the Network.

For what it’s worth, inside a house under the timber stairs I would only use metal as per the CU.
[automerge]1601926555[/automerge]

Hi - as far as I know this SPM is suitable for most earthing systems, I don’t know why that doc doesn’t show it. Here’s a screen shot from another site of perhaps a later spec sheet and it’s got them all listed.
View attachment 61228

Hi thanks for reply.

I was guessing re who installed it. I am not a big fan because its plastic under wooden stairs on only escape route.
It's currently protecting two boards.
Not sure if its acceptable worst case to replace it with stand alone metal spd then come out in to henley blocks to feed the two boards. Or is that considered bad practice?
I know we can have one spd in main and board that protects sub board so I see no issue with my approach. Or does anyone know of better solution.

 

[pc1966]

If your boards are close together so the cable loop from L Henley block to board #1 in to the to SPD and back to N Henley block (also L -> SPD -> MET) is under 1m (ideally under 0.5m) then your one SPD should provide adequate protection for all circuits.

If you are in a high-risk are and/or have a lot of voltage sensitive equipment you might want to see if you can get the loop down to under 0.5m or see if you can put SPD in both, but for most situations it wont be needed.