2.5 mm radial!!!!!

[onzadog]

Hi,
Just wondering if anyone would like to offer any thoughts on my situation.

We've had our boiler moved up into the loft. The old boiler and water meter have been removed. The new boiler is supplied by the old water heater radial which is only 2.5mm. Now for the 5 Amps needed for the boiler, I guess this isn't the end of the world even though I understand radials should be 4mm.

While insulating and boarding the loft, I've found the extractor fan that doesn't work and the shaver socket are both powered from the upstairs lighting circuit. The problem I see with this is that the upstairs lighting circuit ISN'T on the RCD side of the consumer unit.

So, as I've got to spend time in the loft extending some of the lighting circuit so it fits over the insulation I thought it might be wise to sort this out as well. The plan is to fit a SELV zone 1 extractor with the transformer in the loft. I don't want to run it off the light switch as we often shower without the light on so I'll fit a separate pull switch for the extractor.

My thinking was to run the boiler, SELV extractor and the shaver socket of the line that now feeds the boiler. My question is, any thoughts on whether I should upgrade the cable to 4mm and keep it radial or should I put in a whole loop of 2.5 mm and have a ring circuit?

While I'm up there doing this, I might put a socket in the loft just in case, after all. It doesn't add much to the job.

Sorry it's a long one and thanks for any thoughts.

 

[JohnD]

A 2.5mm radial can be 20A which should be plenty (a 4mm radial can be 32A).

If it is a spur it needs to be on a 13A FCU.

A boiler need not be on an RCD. But a loft socket should be (apart from a lot of copper pipes, one of my former colleagues had to report on an accident where a homeowner had dropped his inspection lamp into the cold water tank, and instinctively tried to grab it

 

[Adam_151]

A boiler need not be on an RCD. But a loft socket should be (apart from a lot of copper pipes, one of my former colleagues had to report on an accident where a homeowner had dropped his inspection lamp into the cold water tank, and instinctively tried to grab it

Some of us would consider the risk of falling through the ceiling or getting stranded up there because of a dodgy applicane tripping an RCD to be greater than an electric shock from an inspection lamp, yes 'earthy' pipes are an issue, but unless your lamp is broken, I'd be more worried of a shock from a smashed joint box or a rat chewed cable that I hadn't seen! as for the water tank, rather silly thing to do, but as long as you only put one limb in, and didn't rest any others on pipes, considering the loft floor is wooden then I'm not sure it'd do you much real harm.

Me? I'd use a non-rcd handlamp to go and install a lid on the water tank, I'd rather not have dead mice in water that later gets used to wash the dinner plates (then after that I'd stick a light up there on the lighting circuit and a couple of EM lights as well)

Of course if you wanted to be really safe, you could use a SELV handlamp like they do in confined places on construction sites

 

[JohnD]

... one of my former colleagues had to report on an accident...

(fatal)

 

[Adam_151]

Did the unfortunate fellow place both hands in the tank then? or rest one on a nearby pipe etc?

 

[JohnD]

don't know. I'll guess touching a pipe