SPD wiring

[autolycus]

Hi,

I had an additional consumer unit installed in October as part of a solar install. It's a Fusebox 6-way RCBO board with circuits for 2 x inverters and 1 x EV charger.

Yesterday, the guys that fitted it returned to retrofit an SPD - which wasn't fitted at the time (probably because it was only a couple of weeks after they became a requirement).

They fitted one of these which, as you can see in the picture, comes with it's own MCB.

I'm pretty sure they have connected it up wrongly.

The bottom of the MCB is connected to the busbar in the normal way and a line conductor runs from the top of the MCB to the L terminal on the top of the SPD.
A neutral conductor goes from the top of the SPD to the neutral bar in the consumer unit.

So far so good, but here's where I think it goes wrong....

There is no earth cable going from the PE terminal at the bottom of the SPD to the consumer unit's earth bar. Instead, the PE terminal is connected the same busbar as the MCB and RCBOs. See photo.

I assume they should have cut the busbar at that point so as the SPD was attached to the DIN rail but not to the busbar - right?

They are coming back on Monday to do a couple of other remedial jobs so I can get them to correct this but, in the meantime, I have three questions I'm hoping you people can answer for me please:

1. Am I right in saying the current config is wrong and there should be an earth connection on that PE terminal at the bottom of the SPD (instead of a line one)?

2. Is it safe to leave this as-is until Monday?

3. Will the SPD have been damaged by being connected up wrongly and should I get them to replace it with a fresh one?

Thanks in advance,
David.

 

[ebee]

the SPD should have been fitted to the right of the isolator - by moving the isolator one module to the left first. that means busbar not in the PE terminal and can be wired ok to the earth bar. doesn`t exactly give much confidence in their competence does it?
yes its" safe" to leave and the SPD will not be damaged

 

[pete01]

Never see that before, what did they do with the length of green and yellow that comes in the kit?

Yes as above, SPD on right of main switch and the 32 amp feed mcb on left of main switch.

 

[flameport]

1 - yes, its wrong
2 - yes
3 - it may have been, in that configuration it has the full voltage applied between the N and E terminals all the time, which depending on the supply voltage may have caused damage. Uc on that device is 255V N-E, which is very close to the maximum permitted supply voltage of 253V.

In any case, it's been installed for months in a way not intended by the manufacturer so it should be replaced.

Yesterday, the guys that fitted it returned to retrofit an SPD - which wasn't fitted at the time (probably because it was only a couple of weeks after they became a requirement).

Most of the SPD requirements were introduced with the blue 18th edition, which was published in July 2018 and effective from January 2019.

 

[autolycus]

Never see that before, what did they do with the length of green and yellow that comes in the kit?

Yes as above, SPD on right of main switch and the 32 amp feed mcb on left of main switch.

I don't think I ever saw the earth wire. They arrived with the MCB and SPD already unpackaged. If I'd seen the unused length of green/yellow I'd have queried it at the time.

 

[pete01]

I don't think I ever saw the earth wire. They arrived with the MCB and SPD already unpackaged. If I'd seen the unused length of green/yellow I'd have queried it at the time.

Yes, but as others have said it'll be fine till Monday, let us know what they say, bit embarrassing for them I would assume.

 

[autolycus]

1 - yes, its wrong
2 - yes
3 - it may have been, in that configuration it has the full voltage applied between the N and E terminals all the time, which depending on the supply voltage may have caused damage. Uc on that device is 255V N-E, which is very close to the maximum permitted supply voltage of 253V.

In any case, it's been installed for months in a way not intended by the manufacturer so it should be replaced.


Most of the SPD requirements were introduced with the blue 18th edition, which was published in July 2018 and effective from January 2019.

Thanks, John. The SPD has actually only been installed since yesterday rather than for months, but I still would feel happier if they replaced it with a fresh one on Monday.

I didn't know the SPD requirements dated back that far. My original reason for asking them to come back and retrofit an SPD was because of reading articles like this and this which suggested that Amendment 2 meant you needed an SPD for any new circuit (and especially for an EV one) as of September 2022.

I assume the SPD only protects circuits in the consumer unit it's installed in, and not the entire installation (three consumer units in total)?

 

[Risteard]

Hi,

I had an additional consumer unit installed in October as part of a solar install. It's a Fusebox 6-way RCBO board with circuits for 2 x inverters and 1 x EV charger.

Yesterday, the guys that fitted it returned to retrofit an SPD - which wasn't fitted at the time (probably because it was only a couple of weeks after they became a requirement).

They fitted one of these which, as you can see in the picture, comes with it's own MCB.

I'm pretty sure they have connected it up wrongly.

The bottom of the MCB is connected to the busbar in the normal way and a line conductor runs from the top of the MCB to the L terminal on the top of the SPD.
A neutral conductor goes from the top of the SPD to the neutral bar in the consumer unit.

So far so good, but here's where I think it goes wrong....

There is no earth cable going from the PE terminal at the bottom of the SPD to the consumer unit's earth bar. Instead, the PE terminal is connected the same busbar as the MCB and RCBOs. See photo.

View attachment 305052

I assume they should have cut the busbar at that point so as the SPD was attached to the DIN rail but not to the busbar - right?

They are coming back on Monday to do a couple of other remedial jobs so I can get them to correct this but, in the meantime, I have three questions I'm hoping you people can answer for me please:

1. Am I right in saying the current config is wrong and there should be an earth connection on that PE terminal at the bottom of the SPD (instead of a line one)?

2. Is it safe to leave this as-is until Monday?

3. Will the SPD have been damaged by being connected up wrongly and should I get them to replace it with a fresh one?

Thanks in advance,
David.

Imbeciles.

 

[ebee]

"3 - it may have been, in that configuration it has the full voltage applied between the N and E terminals all the time, which depending on the supply voltage may have caused damage. Uc on that device is 255V N-E, which is very close to the maximum permitted supply voltage of 253V"

Good point there Flameport, I hadn`t considered that