Rewire Questions

[ppelec100]

I've been to see a flat which needs a rewire. The flat is being completely renovated. I've just recently qualified, I have done rewires before during my apprenticeship and understand it, but it is the first time taking one on on my own, I feel pretty confident as it is all partition walls which makes it easier. I have a few questions I was hoping you could help with:

Q1. How do you guys decide whether to install an RCD or RCBO board?
Do you pick based on the client/budget? I know an RCBO has the advantage of not wiping out half the place. So does it come down to price?

Q2. Type A or AC RCD/RCBO? I was going towards type A, I want to know what you guys think?

Q3. I am going to install smoke/heat detectors but what are the requirements? Which rooms need it? The kitchen I will put a heat of course! A smoke in the utility room and hallway. But is it necessary in the bedroom? Can anyone point me in the right direction where to find the info?

Q4. Heights for sockets and switches? I know the 450mm and 1200mm applies to mainly new builds. what heights would you recommend?

Q5. Dimmable LED strips with drivers. Can anyone recommend any good ones? Will I be able to put them on the same gang switch as the kitchen ceiling lights? They will be going under the kitchen units to light up the worktop. I've never bought any myself to install.

Q6. Are there any dimmer switches/modules which can work as master and slaves? The rewire specifies a 2 way intermediate in the bedroom and a 2 way in the kitchen/lounge.

Q7. Last but not least, the most famous question! How do you quote for the job? It is in central london. I have put £60 per socket/spur/switch, £50 for light/smoke/ex fan/appliances(mirror), £80 per hob point, £150 a grid switch (THEY ARE A NIGHTMARE IN MY OPINION). Is this too low? Do you guys price per point or hourly/daily?

What else do I need to know? Any other information would be appreciated.
I know I have to notify building control, I will get the tester to deal with this.
I have bought the building regs book its on its way, anything specific to read in there?

THANKS FOR ANY ANSWERS, HAVE A COOKIE ?

 

[Mike Johnson]

I could never work out how an AC type would be more suitable than an A, I think it all used to be down to cost, but this has largely been eroded in recent times.

And a bit controversial why they are still available as single pole. (tin hat)

 

[ppelec100]

Is your tester registered Third Party Certification?

Oui

 

[ppelec100]

Fitted dozens of Fusebox CU's and they are fine.

Agree that the heights are for new builds but why not bring the installation up to modern standard when you have an opportunity to do so.

I dont understand how you will get somebody else to test and sign off your work?

Initial verification...?

Me as the designer and constructor, him as the tester?

 

[pc1966]

I was thinking to go with Fusebox RCBO board with all type A.

For many that is the default sort of choice, as type AC RCD are going out almost certainly with revised regs and the cost of the Fusebox RCBO setup is not much more than a dual RCD board.

Also they have SPD (I think) as standard, if not make sure that is included. Some ask the client and get drawn in to arguments on the risk vs. cost but for the < £100 for one on practically any board it is hardly worth the time and effort to quote two figures and discuss/justify it.

 

[Pete999]

Initial verification...?

Me as the designer and constructor, him as the tester?

Will that be proper testing ,or your say so job done, cash runner?

 

[Midwest]

Will that be proper testing ,or your say so job done, cash runner?

I think his Frenchy Third Party Tester will want to paid properly for a proper professional job.

 

[Midwest]

I'm doing something very similar @Pete999, and I will only expect a professional job for my money. Can't see why the OP won't expect the same?

 

[ppelec100]

Will that be proper testing ,or your say so job done, cash runner?

PROPER TESTING!

 

[LastManOnline]

A new question arises:

When I went to see the place, the ceiling fan was wired, but the flexible ducting went up then into a flat pvc straight duct (approx 100x50mm) then went to somewhere where I could not see visually.

They said they will have a loft hatch in the bathroom as soon as you enter.

How would I go about deciding which fan to get?
I was thinking a centrifugal fan?
Was thinking about those inline fans too but you would need to climb into the loft space, and where the inline should be put, I don't think the ceiling will be too stable to work on...

An online fan is a great option when you have a loft as you get the benefit of noise reduction too. Which is especially handy at night. Your issue will likely be the 4 " exit hole. Will it be roof, wall or possibly soffit. You need to check the easiest option. If it's too difficult for you to do yourself get the homeowner to arrange it

 

[ppelec100]

An online fan is a great option when you have a loft as you get the benefit of noise reduction too. Which is especially handy at night. Your issue will likely be the 4 " exit hole. Will it be roof, wall or possibly soffit. You need to check the easiest option. If it's too difficult for you to do yourself get the homeowner to arrange it

Should an inline be fitted in with a standard/timer axial fan or just a grill?
It is in a flat I am not sure where it goes out, if I take the job on, I will investigate when doing the downlights.

 

[LastManOnline]

Should an inline be fitted in with a standard/timer axial fan or just a grill?
It is in a flat I am not sure where it goes out, if I take the job on, I will investigate when doing the downlights.

Timer on the fan is the homeowners call. I usually wire the fan direct to the light switch rather than loop it from bathroom light. If homeowner wants fan switched separately he then has that option.

 

[ppelec100]

Timer on the fan is the homeowners call. I usually wire the fan direct to the light switch rather than loop it from bathroom light. If homeowner wants fan switched separately he then has that option.

sorry let me rephrase, what I meant was... If I install the inline fan in the loft space like you recommend because of of the noise, am I meant to install the inline fan motor with an axial fan or just the inline fan on its own with a grill? I would of thought it would be better with an axial fan as the axial fan pushes to the inline, then the inline helps push it out more...
yes I agree with the separate switching, I have that at home

 

[Deleted account]

When you say axial fan, do you mean centrifugal .

 

[ppelec100]

When you say axial fan, do you mean centrifugal .

axial as in the normal standard/timer fans with average suction power.
what would you recommend?

 

[LastManOnline]

sorry let me rephrase, what I meant was... If I install the inline fan in the loft space like you recommend because of of the noise, am I meant to install the inline fan motor with an axial fan or just the inline fan on its own with a grill? I would of thought it would be better with an axial fan as the axial fan pushes to the inline, then the inline helps push it out more...
yes I agree with the separate switching, I have that at home

My modus operandi with inline fans has always been to buy the complete kit from the wholesalers.I always go for highest wattage. Nothing as pleasing as watching a sheet of toilet paper stuck to the grill when extractor fan operates. I normally connect fan with flex first and check its operation before installing it in the attic. If fan has a timer I make sure homeowner decides the overrun time before I install it. It can be a nuisance mucking about with a fan timer in a small attic. Lastly a little rubber placed between the fan and the wooden grounds it's mounted to reduces vibration and noise.

 

[ppelec100]

My modus operandi with inline fans has always been to buy the complete kit from the wholesalers.I always go for highest wattage. Nothing as pleasing as watching a sheet of toilet paper stuck to the grill when extractor fan operates. I normally connect fan with flex first and check its operation before installing it in the attic. If fan has a timer I make sure homeowner decides the overrun time before I install it. It can be a nuisance mucking about with a fan timer in a small attic. Lastly a little rubber placed between the fan and the wooden grounds it's mounted to reduces vibration and noise.

soooo do you use the inline fan with just a grill mounted in the ceiling of the bathroom then? you don't use the inline + ordinary extractor fan? could you link me the kit pleaseeee

 

[LastManOnline]

soooo do you use the inline fan with just a grill mounted in the ceiling of the bathroom then? you don't use the inline + ordinary extractor fan? could you link me the kit pleaseeee

Apologies. Misunderstood your question. Your phrase "inline + ordinary extractor fan" is unfamiliar to me. An inline fan by definition is "in the line" of air extraction with a flexi connected to the ceiling grill in the bathroom and a flexi connected to the wall or roof outlet. An ordinary extractor fan has a flexi on one end only. Don't have any links to hand but it's a standard item in any wholesalers

 

[ppelec100]

Apologies. Misunderstood your question. Your phrase "inline + ordinary extractor fan" is unfamiliar to me. An inline fan by definition is "in the line" of air extraction with a flexi connected to the ceiling grill in the bathroom and a flexi connected to the wall or roof outlet. An ordinary extractor fan has a flexi on one end only. Don't have any links to hand but it's a standard item in any wholesalers

so from the grill, how far into the flexi ducting do you install the in line fan? would you recommend straight duct over flexi duct if it is possible? because of the air flow resistance when hitting the grooves of the flexi duct?

 

[Mike Johnson]

Its not the airflow resistance on flexible ducting I find that is the problem, but the condensation that occurs on the grooves if extracting from a bathroom or kitchen, condensation trap and drain needed, if possible I try to always use solid duct, not popular as its more difficult to fit and takes time, any inline fan I also suspend from the rafters in a loft installation as this cuts down the noise considerably.

 

[ppelec100]

Its not the airflow resistance on flexible ducting I find that is the problem, but the condensation that occurs on the grooves if extracting from a bathroom or kitchen, condensation trap and drain needed, if possible I try to always use solid duct, not popular as its more difficult to fit and takes time, any inline fan I also suspend from the rafters in a loft installation as this cuts down the noise considerably.

There is no rafters, this is a flat with a concrete ceiling above the plasterboard. Would you say to suspend it from the concrete ceiling then? Can I not put it in a big enclosure to trap the noise? Suspending seems like a lot of work

 

[Mike Johnson]

Or Lord mount it straight onto an external wall.

 

[LastManOnline]

so from the grill, how far into the flexi ducting do you install the in line fan? would you recommend straight duct over flexi duct if it is possible? because of the air flow resistance when hitting the grooves of the flexi duct?

Straight duct is always preferable but circumstances may limit its use. Your exit hole location (roof, wall or soffit) and your extract fan location will determine what you use. You will want to keep your duct run as short as circumstances allow. From the grill I normally mount the fan approx 2 to 3 feet away using flexi.If the exit is through the roof then I use another section of flexi. If the exit is through the soffit (or wall) it's usually a longer run and here is where straight duct is useful to provide a nice sloping flow to the exit hole with the final foot again in flexi

 

[ppelec100]

Or Lord mount it straight onto an external wall.

? how about I stick a hoover on the other side of the inline super sucker!

 

[ppelec100]

Straight duct is always preferable but circumstances may limit its use. Your exit hole location (roof, wall or soffit) and your extract fan location will determine what you use. You will want to keep your duct run as short as circumstances allow. From the grill I normally mount the fan approx 2 to 3 feet away using flexi.If the exit is through the roof then I use another section of flexi. If the exit is through the soffit (or wall) it's usually a longer run and here is where straight duct is useful to provide a nice sloping flow to the exit hole with the final foot again in flexi

Okay got you! its possible for me to use a straight duct as the rest continuation of the flat pvc duct is above the existing fan location. When doing a 90 degree bend into the duct would you recommend putting 2 x 45 degrees together then for the swooping like you said?

 

[ppelec100]

Straight duct is always preferable but circumstances may limit its use. Your exit hole location (roof, wall or soffit) and your extract fan location will determine what you use. You will want to keep your duct run as short as circumstances allow. From the grill I normally mount the fan approx 2 to 3 feet away using flexi.If the exit is through the roof then I use another section of flexi. If the exit is through the soffit (or wall) it's usually a longer run and here is where straight duct is useful to provide a nice sloping flow to the exit hole with the final foot again in flexi

Or Lord mount it straight onto an external wall.

Do you install a 3amp fuse inline of your extractor fans? they show on the installation instructions to do it...