Rcds as main switch

[i=p/u]

Fuse board with say 80A rcd main switch on a tt system .

I seen guy at work at wrote on sheet as non compliant as rcd main switch should be before fuse board to protect tails.

Is is he correct ,

i would say say no as there's still going to be gap if even if he put in rcd before board

 

[Octopus]

What is the cu made of?

 

[Leesparkykent]

Even if the CU is metal the 100mA S type RCD doesn't have to go in the tails before it enters the CU. The RCD would be classed as similar switch gear so would have to be installed in a non combustible enclosure anyway ..the tails should be adequately supported and enter to cu using a nylon/plastic tail gland to minimise movement/abrasion. It would be prudent to replace the main switch with a 100mA S type to provide earth fault protection to the flexible links that go from the main switch to feed each RCD.

 

[Risteard]

The RCD would be classed as similar switch gear so would have to be installed in a non combustible enclosure anyway

I don't think it's so clear cut that an RCCB in an enclosure without any overcurrent protective device can be defined as a "similar switchgear assembly" to a type tested distribution board. I suspect opinions on this will differ for some time!

 

[Leesparkykent]

I don't think it's so clear cut that an RCCB in an enclosure without any overcurrent protective device can be defined as a "similar switchgear assembly" to a type tested distribution board. I suspect opinions on this will differ for some time!

I thought you would say this when I posted the above lol . I totally understand where your coming from though as the rcd offers no OCP but still im of a different opinion. Not that it means much but had my scam assessment last Tuesday and spoke to my assessor about it and he is of the same opinion as me.

 

[Risteard]

I'm certainly not saying that my view is correct - simply that it isn't entirely clear.

Clarification on this point would be welcome, although until such time as the Regulation is rewritten this would merely be someone or some organisation's opinion!

Incidentally, I haven't asked my Area Engineer for his take on it.

 

[Leesparkykent]

I'm certainly not saying that my view is correct - simply that it isn't entirely clear.

Clarification on this point would be welcome, although until such time as the Regulation is rewritten this would merely be someone or some organisation's opinion!

Agreed..421.1.201 is a bit of a joke Imo and hopefully the ambiguity can be cleared up in the 18th or even better be retracted altogether lol. I like amendment 3 boards as better than the flimsy plastic rubbish that we was getting provided with but things like RCDs in insulated enclosures , rec supply isolators and insulated switch fuses should be aloud to be fitted without being housed in a non combustible enclosure.. Next we will have metal switched fused spurs with gravity lids as they will fall under the term similar switch gear lol

 

[Risteard]

I like amendment 3 boards as better than the flimsy plastic rubbish that we was getting provided

No question! I would think anyone who does a lot of non-domestic work would in general prefer steel to crappy plastic that warps when you look at it the wrong way!

 

[ipf]

No question! I would think anyone who does a lot of non-domestic work would in general prefer steel to crappy plastic that warps when you look at it the wrong way!

Never seemed to be such problems with the old Wylex solid units with double screwed terms, eh?

 

[Risteard]

Never seemed to be such problems with the old Wylex solid units with double screwed terms, eh?

I would love to see double screw terminals back instead of cage clamps, but I think a change to manufacturing standards would be required to permit this.

 

[Midwest]

I think now that we have been instructed down this route, I can't see any other recommendation coming out other than metal. I can see a nice little insert for BS7671 421.1.202, 203 etc anytime soon, or a more descriptive definition of 'similar switchgear assemblies'. If you now fit an RCD in a plastic enclosure in a domestic property, you'll be having to pop back to replace it with a metal enclosure.

 

[Leesparkykent]

I would love to see double screw terminals back instead of cage clamps, but I think a change to manufacturing standards would be required to permit this.

The M2 consumer unit has twin screw tunnel terminals but only on the main switch...on the down side though I think they are made by Proteus.http://m2electrical.co.uk/circuit_protection/consumer_units/

 

[Risteard]

The M2 consumer unit has twin screw tunnel terminals but only on the main switch...on the down side though I think they are made by Proteus.M2 Concept Automation

I don't think M2 is made by Proteus, but they are both CEF-owned manufacturers. Also MCG.

EDIT: Having Googled M2 & Proteus may be made in the same factory.