Best idea for RCD protecting this extension to a domestic lighting cct

[freedomrun]

DOMESTIC, TN-S, 60A DP switch, BS3036 5A fuse, no RCD, customer wants an Bathroom Extractor in 13" outer wall. I was gonna run some plastic mini trunking from IP44 light fitting to pull switch, Mount Isolator switch outside Bathroom on wall. Only need to RCD protect this part of the cct - any suggestions, also this is not in London - how much do you think i could charge seeing as it's old Victorian with quite thick walls. I'm gonna use a 20 quid fan, or something on offer around that price.

 

[malcolmsanford]

If possible I would fit a little RCD enclosure at the CU. Feed the RCD from the lighting 3036 and then divert the whole of the lighting circuit into the RCD.

I gather your going to have to core drill that 13" wall, do you have a core drill, or are you going to hire one? I would not be attempting to drill that wall with even a decent SDS drill, as you could really hurt yourself.

 

[freedomrun]

The 13" wall must have a cavity, so not a solid one - was going to CORE DRILL with my SDS, but to be honest i've not had to do this before as it has luckily been done already. What should i watch out for?? The customer is giving me grief over the RCD protection (like they do) but as it's an extension to a cct in a bathroom he knows he has to have one, dose'nt want to pay for it. Just thought i would ask you guys the best way to go about this job really as you are such a nice bunch !! I was thinking of charging around 200 quid all in?

 

[IQ Electrical]

DOMESTIC, TN-S, 60A DP switch, BS3036 5A fuse, no RCD, customer wants an Bathroom Extractor in 13" outer wall. I was gonna run some plastic mini trunking from IP44 light fitting to pull switch, Mount Isolator switch outside Bathroom on wall. Only need to RCD protect this part of the cct - any suggestions, also this is not in London - how much do you think i could charge seeing as it's old Victorian with quite thick walls. I'm gonna use a 20 quid fan, or something on offer around that price.

Is there no way you can mount the fan on the ceiling and duct away in the loft? (assuming 1st floor bathroom).

 

[malcolmsanford]

You can use an SDS but have a chance of 1 burning it out, 2. having it bite on you and it is not nice when it does that.
I'm biased but I hate core drilling, and so I bought myself a core drill, but I was a coward lol.

I think you may have over priced yourself there, it would be what a mornings work so perhaps 100-115 pounds

 

[LOYDE]

I agree, wall construction is critical in deciding how to create the hole through the wall.
If its a stone wall with a lath n plaster finish a core drill will make more mess than you may imagine.
Is it a cavity or solid wall?
Best case would be rendered brick cavity with render skim internal finish. You could drill in from outside so as not to blow the render when the core bit breaks through and then the same from the inside out.

But.....if its worse case horsehair **** and stone rubble solid wall construction with internal timber wall lath and plaster finish....

You could use the core drill to get a nice round hole from outside in. Then bolster the external render from the hole cut. Get breaker bbit in end of drill and hope the local stone is crumbling as you slowly open up a hole till you get through to the rear of the internal lath n plaster wall.
Then go inside get fien multi tool out and a fine bit cut through plaster to expose the lath below then carefully cut out lath keeping cuts to usee to reinforce the wall where you have cut the latrel strengh out of lath wall making the hole through it ( or when some one leans on it it will crumble)

 

[LOYDE]

Agree with IQ into loft space out through soffit, so much easier....

 

[freedomrun]

Should have stated, it's a GFF & has another property above - only option is through the wall, Red brick (victorian) but 13" thick maybe has a cavity.

 

[LOYDE]

If you HAVE to drill the wall....... I imagine this victorian is red brick clay type drill a pilot hole same size as core drills guide drill bit. then from outside in go about 4" in then go inside and drill out.
This takes away chance of core bit breaking out two much as it punches through the last bit of brick.

x4 6mm plugs, x4 stainless screws (rust proof) push length of 100mm extractor flex through ducktape to vent cover fix vent cover fit fan easy should take 2 hours max to setup fit and wire extractor+vent.
Add on time for any circuit alterations and circuit testing to ensure can cope with existing plus extra demands..

 

[LOYDE]

p.s if it is a cavity don't let anything fall down it as can cause damp problems with cavitys being bridged by shi*e

 

[Engineer54]

p.s if it is a cavity don't let anything fall down it as can cause damp problems with cavitys being bridged by shi*e

That's a bit of an old wives tale. in reality, you will find that in most cavity walls, the inner and outer have been bridged numerous times throughout the whole wall, since the day they were built. Normally by wet mortar falling down and sticking on to the wall ties, and of course the ties themselves.