Fusebox SPDs

[Kuba]

I'm trying to understand a bit more about SPDs. I haven't installed one yet and will have to soon in order to progress with my NVQ (have to do a board upgrade). I found these two boards from the same wholesaler. From what I understand, the one with double SPD is wired 'before' the main switch and the other single SPD with a 32a mcb is wired 'in front' of the main switch with all other mcbs/rcbos? Why would you chose one over the other one and what are their benefits/uses? Thanks for all your help.

 

[westward10]

Regulation 534.4.5.1 states "SPD installations shall be protected against overcurrent with respect to short-circuit currents". It then states "This protection may be internal and/or external to the SPD according to manufacturer's instructions".
So in your two examples you have external protection by way of the 32A device and probable internal protection within SPD where no separate device is present. Because the SPD which has no separate protection is factory fitted we can assume it is compliant although you should always verify this with the manufacturer if you have any doubt.

 

[Kuba]

Regulation 534.4.5.1 states "SPD installations shall be protected against overcurrent with respect to short-circuit currents". It then states "This protection may be internal and/or external to the SPD according to manufacturer's instructions".
So in your two examples you have external protection by way of the 32A device and probable internal protection within SPD where no separate device is present. Because the SPD which has no separate protection is factory fitted we can assume it is compliant although you should always verify this with the manufacturer if you have any doubt.

Thanks for that! It was that obvious ?

 

[Lister1987]

Regulation 534.4.5.1 states "SPD installations shall be protected against overcurrent with respect to short-circuit currents". It then states "This protection may be internal and/or external to the SPD according to manufacturer's instructions".
So in your two examples you have external protection by way of the 32A device and probable internal protection within SPD where no separate device is present. Because the SPD which has no separate protection is factory fitted we can assume it is compliant although you should always verify this with the manufacturer if you have any doubt.

I seem to recall that when fusebox were initially queried on it thru stayed their SPD didn't need overcurrrent protection and a short time after stock come out with an overcurrrent protection MCB. Does beg the question if noone challenged it, would they have changed it to have an MCB for protection?

 

[westward10]

I seem to recall that when fusebox were initially queried on it thru stayed their SPD didn't need overcurrrent protection and a short time after stock come out with an overcurrrent protection MCB. Does beg the question if noone challenged it, would they have changed it to have an MCB for protection?

I did not realise this so if you have one with no external protection you definitely need to consult the manufacturer. Hager ones come with no separate protection.

 

[SJD]

• Initially (e.g. 1 year ago) Fusebox fitted a double width SPD directly connected (no MCB).
• Later (mid-2020), they decided it did actually need to be fitted after an MCB (B32), and added one. This meant their consumer units were all 1-way less, so a 10-way had 9 usable ways, etc.
• Very late 2020, they changed to a single-width SPD, plus B32 MCB.
  That meant the consumer units again had the original number of usable ways.

If you buy one now, you'll get the single-width SPD & MCB, unless someone is trying to dispose of old stock! You can tell from the part numbers, e.g. F2010MX is newer type (10-way), F1010MX is the old type (only 9-ways if MCB fitted).

 

[baldelectrician]

I did not realise this so if you have one with no external protection you definitely need to consult the manufacturer. Hager ones come with no separate protection.

Yes, but I trust Hager, in fact I have a dual stacked Hager RCBO unit with SPD next to the main switch

 

[Kuba]

@westward10 @SJD @baldelectrician I ended up buying this board from Fusebox but got bit surprised about position and the amount of knockouts. This is going to be my first proper board upgrade on my own so I want to make sure it's spot on and looks good (plus it'll be reviewed by my NVQ assessor). As you can see I only have 2x 20mm and 2x 32mm knock outs on the top. I have four circuits, 2x 1.5mm and 2x 2.5mm rings. I have to use a 32mm knock out in the bottom for my tails and earth. Would it not look stupid if I brought my rings through two 32mm gland on the top? I hoped the board will have 25mm knock outs for that... Thanks for advice

 

[SJD]

I think originally there were more larger knockouts, and Fusebox changed to a mix of 20 and 32mm ones, as it is always easier to enlarge one that reduce it! You've chosen quite a small board, the larger boards obviously have more knockouts.

I often enlarge a 20mm knockout to 25mm and fit a Wiska/Sprint 25mm gland that is designed for 2x2.5mm2 T&E, using a cone-cutter bit.

Sometimes I do use a 32mm gland with a Wiska/Sprint gland designed for 10mm2 T&E that nicely takes up to 4 off 1mm2 T&E if I have quite a few lighting circuits (they fit sideways in the gland).

 

[Kuba]

I think originally there were more larger knockouts, and Fusebox changed to a mix of 20 and 32mm ones, as it is always easier to enlarge one that reduce it! You've chosen quite a small board, the larger boards obviously have more knockouts.

I often enlarge a 20mm knockout to 25mm and fit a Wiska/Sprint 25mm gland that is designed for 2x2.5mm2 T&E, using a cone-cutter bit.

Sometimes I do use a 32mm gland with a Wiska/Sprint gland designed for 10mm2 T&E that nicely takes up to 4 off 1mm2 T&E if I have quite a few lighting circuits (they fit sideways in the gland).

I see.. I had to go for a small board because I only have >300mm space to fit it in unfortunately. I have no use for 32mm knock outs and really needed a mix of 20&25mm but might have to use 32mm for rings and 20mm for radials (lights and smokes)? Unless I cut 25mm holes somewhere on top but that will make it look like a dogs dinner ?