oversized MCB's

[tradeite]

I am an electrician nearing retirement, so really I should know this but am not sure. I have not done any installation or real heavy electrical work for some years now. I have a small business, dealing with the maintenance of student accommodation buildings. Electrical, plumbing, carpentry, gardening etc. I have not done an eicr for a while but have in the past and am qualified. I was asked whether I would undertake the eicr on one of my regular sites and the money I was offered was too good to turn down.
I was let down by two electricians. Therefore have been doing the job myself. I am most of the way through it, took nearly a year, due to the size, over 300 boards and the Covid restrictions. My question is this. There are 1Kw heaters in each of the rooms and they are all protected by a 20A type B mcb. By my reckoning it should be 6A. Also there are Wi fi routers in the flat clusters, also protected by a 20A mcb, they only draw a very small current. The loop, and pfc check out o.k.
Do I record this as a C3 ? There are over a thousand like this in the building. Also in a lot of the boards, there are no covers on the unused live terminals. Do I record this as a c3. The installation itself is only 6 years old and I have not found many problems, apart from 2 faulty RCD's and some loose terminals. which we have rectified as we went along.

 

[Burtones]

The MCB's are there as overcurrent protection to protect the fixed wiring rather than what's connected to them so as long as they are smaller than the cables current carrying capacity given the install method then they are fine. How is each heater connected though? Through a fused connection unit?

 

[Strima]

As long as the cable rating and installation method allow it no code required.

 

[DPG]

You say the wifi routers are protected by a 20A MCB. How are they connected?

 

[Flanders]

As above as mcb protects the circuit, as long as the equipment connected to it is protected by a fused spur with the correct size fuse to protect the supply cord to the appliance then there would be no requirement to code it. As for the exposed bus bar .as long as it is not accessible with the cover on and a tool is required to remove the cover then this would also not be coded in my opinion

 

[Dartlec]

When you say no covers in the boards, do you mean no blanks in the board cover? or only once the cover is removed.

Blanks missing from the cover front is potentially a C1, but easily fixed with the standard metal blanks (or even push in plastic ones). Nothing once the cover is removed is no code at all, as long as the cover needs a tool to remove it (Best Practise Guide 4) is a good resource for this)

I assume the routers are connected via a plug or some sort of fused spur? in which case it's fine.

Same with the heaters - should probably be on a fused spur, but even if they weren't, they are a fixed load and not liable to overload so as long as the cable is appropriately sized for a 20A MCB (probably 2.5mm T&E), then there is no code needed.

Were there any certificates from the original installation, since this is less than 6 years old?

 

[DefyG]

I assume the routers are connected via a plug or some sort of fused spur? in which case it's fine.

Agreed, although probably by transformer plug as 9 or 12v? therefore 230v circuit protected at 20A would be fine to a 13A socket outlet.
The heaters (as others have said) are probably connected via a S/FCU but if not very poor design if only 6 years old.

 

[Dartlec]

Agreed, although probably by transformer plug as 9 or 12v? therefore 230v circuit protected at 20A would be fine to a 13A socket outlet.
The heaters (as others have said) are probably connected via a S/FCU but if not very poor design if only 6 years old.

I wondered if they might be the commercial type ceiling mounted routers, rather than domestic ones (which almost always have a transformer plug). In which case, the manufacturer's instructions should specify what connection they need - though can't see that they could ever really overload in a way that would threaten the cable...

Poor design sometimes seems to be more common the more recent the build is, and I'm guessing as student accomodation they weren't splashing money on them.

It's possible that whoever designed the circuits was different from whoever fitted the heaters, so things like this can be missed.

 

[tradeite]

Thankyou for all your replies! Both the Wifi and heaters are connected via spurs. As for the previous test sheets, they are a joke. They are enclosed in a big fancy folder with posh looking certs. Half of the results are not there. The figures inserted are a mish mash. For example cooker circuit on a 6mm radial, it states that the number of points served is 7. That is on every sheet.