Consumer unit with no isolation of N

[SJD]

Came across a consumer unit today, where there is no means of isolation of the N, see below.

The property is a flat, fed with 4-core SWA plus a separate 16mm2 E, from a TN-C-S supply via a TPN switch fuse in a communal meter cupboard.
There are 3 supplies - 24hr, plus 2 off-peak supplies (immersion, storage heater).
You can see two additional main switches on the right (fed by the blue and the yellow cores of the SWA).



Since there is only one N bar in the consumer unit, I guess a practical option was to just not switch the N.

Reg 461.2 tells me it is allowed to omit switching N from a TN-C-S supply (providing a couple of conditions are met).
Reg 462.1.201 tells me the main switch for use by ordinary persons must interrupt both live conductors of a single phase supply.

Technically if the main switch is the TPN isolator (in the locked communal cupboard) then this might be OK?
But the flat occupier would regard the 3 main switches on the consumer unit in the flat as the main switch, and this is not OK?

My initial reaction was this is not allowed, but I'd be happy to be corrected.

NB there is a warning to switch off all three main switches on the outside casing of the consumer unit to isolate it.

 

[Strima]

Swap for a four pole switch.

 

[SJD]

I guess one option would be to fit a 4-pole switch.

In the event a new consumer unit gets fitted at some point, I think multi-tariff consumer units tend to retain multiple main switches, if I recall, rather than one big main switch.

But I wanted to be certain as to whether something needs to be done about the N switching, or not.

 

[James]

I think I would prefer to see a main switch before the dB that isolates all conductors.
However I am not convinced that what you have there is not allowed.

 

[SJD]

I think I would prefer to see a main switch before the dB that isolates all conductors.
However I am not convinced that what you have there is not allowed.

That is my position, but I don't want to be telling a customer they need this done if it actually isn't the case.

 

[richy3333]

Up here when we have multiple tarrifs on SP installation there is always a neutral, normally commoned via a Henley block after the meter. Sometimes a triple pole isolator switch but not often.

 

[James]

After giving this some thought, there is a single point of isolation available in the meter cupboard
So I would be happy with that providing that there is a warning on the cover of the dB.

I would like to see the blue and yellow cores sleeved or taped so they can’t be confused.

 

[ipf]

Interesting innovation. I can't help thinking that a CU and a DB are completely different things, though, and should be treated as such.
With a 3 ph DB, the neutral wouldn't have to be switched....so why does it have to be in this concoction?