Is this about right?

[ChrisR]

I'm a gas man. I've only done limited scope Part P so know v little about practical electrics apart from what you need to pass that. Power factors, electronics, easy - what you have to do in a house, burgared if I know...

Missus wants the bathroom done so we're getting a man in.
There's a Jacuzzi pump under the bath, says it needs a 13A fuse but the continuous load isn't anywhere near that high.
Also underfloor electric, about 200W. That's got a timer/stat which can't go in the bathroom so it can go in the loo next door, with its isolator and the one for the bath pump.
Also there's a light over the mirror, and a shaver point in the same bathroom wall cabinet thing. Feed from those is from the lighting cct.

I'm hoping the pump and underfloor heat can come either
1) off a single spur off the ring, via a jb, as there's no ring in the loo...
or
2) off a disused 4mm radial from the old Wylex CU.

All circuits except the lights are off a (separate from the CU) 30mA RCD.

The wall cabinet/light/shaver point means the lights cct will need an RCD, right?
So if we put another separate one in, will that "do"?? And avoid cross bonding?

Solid exists, dotty proposed:

OK, shoot me down!

 

[Steve]

Just fit an RCD on the lighting circuit "branch" to the bathroom.

The rest of your lights dont need RCDing, you are only altering the bathroom wiring, the rest of the installation doesn't need updating to 17th.

Though I'd look at getting the Wylex changed.

 

[ChrisR]

One for the loo at high level perhaps!
It's just a T&E in egatube buried in the wall from the loft..

Presumably RCDs on lighting circuits tend to trip when a bulb goes, (putting the lot out)?

 

[ericmark]

One for the loo at high level perhaps!
It's just a T&E in egatube buried in the wall from the loft..

Presumably RCDs on lighting circuits tend to trip when a bulb goes, (putting the lot out)?

My RCD does not trip due to bulb blowing. No earth on bulbs so not likely to. However they have been known to trip the MCB.

And yes now that MCB's and RCD's are the norm one is more likely to lose lights especially should you have a fire. As a result the light over my stairs is battery backed.

However there does not seem to be anything wrong with the wiring shown and I expect the LABC will pass it.

Power Factors and electronics easy

I have a degree in electrical/electronic engineering and I would not say that. Complex numbers are not covered until "A" Level and I would question how many fully qualified electricians can work with J? (That's i to non engineers).
And to just work out size of heat sink required with electronics is hard enough without looking at Karnal Mapping. So if you can do all that then house bashing should be easy pesy!

 

[ChrisR]

Thanks chaps.

I have a degree in electrical/electronic engineering

Me too, but there's lots I don't know about how stuff actually gets put in houses. I was surprised how little the Part P course covered.

Karnal maps? Never heard of them.
Karnaugh maps of course, for login condensation..
Heat Sinks? Fluid dynamics, complex stuff. Or use the plumber's approach - put one in twice as big as you think you'll need.....
It was Fourier transforms that gave me butterflies.