Do I need a new consumer unit for 3 new smoke alarms?

Bit more info may help - I presume the existing CU is a make or model for which RCBOs are not available, and/or is jammed full ? New circuits do not have to be RCD protected, but it severely restricts the type of cable and or where it is permissible to route it. Conventional Flat twin and earth without RCD or RCBO protection at 30mA is likely to not meet current standards almost anywhere But a cable with an earthed foil or armour may be used in many cases.

In different situations, either quote you have been told may be right. also note that a new CU is not the only way to add 30mA RCD protection to a circuit. though it may be the neatest.

mike

If the alarms are radio linked, and so can be individually wired into exiting circuits, it seems likely that any new cabling would only be in ceiling voids - thus wouldn't be subject to the requirement for soft-sheathed cables concealed in walls to have 30mA RCD protection.

I presume none of them will be an a bath/shower room either so no requirement on that score either. Nor socket outlets or mobile equipment outdoors. The front-end 100mA unit should provide adequate ADS even if you're on a TT system.

The only remaining one I can think of is the relatively recent requirement for domestic lighting circuits to have 30mA RCD protection - we could probably debate whether applying that to a length of new cable that supplies no lights comes under the heading of "strictly correct" or "overzealous", since only the new work strictly has to comply with the latest regulations.

On the other hand, it sounds like your installation is a little behind the times safety wise, so this might be a good opportunity to brings things up to scratch (finances permitting).

    - Andy.

Thanks Andy. That was my interpretation after reading the regulations. Wires would be in the ceiling void and not in a bathroom.  I am trying to avoid the cost of a new CU if at all possible. But I also want to make sure we comply with regulations.

Cheers, Steve

Hi Mike. Yes , the CU is full and regs are happy for us to use existing downstairs lighting circuit.  The wires would come off existing electrical wires in the ceiling and not in a bathroom. So, I'm struggling a bit to understand why this electrician is insisting on it but can see that the regulations can be interpreted different ways. I want to make sure we comply with regulations but can't really afford the additional substantial cost, in the context of a simple 3 smoke alarm fittings

Cheers, Steve

Dare we ask the price of a new CU?

I've been quoted between £700 and £900 on top of the other bits I need doing. So best part of £1300 all in

Seeing as how building control are happy to design your smoke alarm system, one in garage, lower and upper stairs, would they be happy with tamperproof battery interlinked smokes such as Aico EI650RF Battery Interlinked RadioLINK+ Smoke Alarm | Smoke Alarms | Screwfix.com ?

No electrician needed

I presume the garage conversion has it's own consumer unit with 30m/a protection and had an existing suitable sub-main.  Could the smokes be fed from there if you don't want to go wireless ?

Gary

Hi Gary

the new room in the original garage are using the existing CU and the downstairs lighting circuit. So running off 100. Not allowed completely wireless alarms. Have to be wired to the electrics with radio units 

cheers, Steve

So all of the new wiring in the garage conversion is almost certainly non compliant if it's on a 100m/a rcd. 

Gary