Kitchen electrics question

[rjb2001]

Hi Guys,
Just been enquiring about a new kitchen and wanted to check on some info to make sure I'm not about to be ripped off...

Electrician from fitters came round and made two points:

a) Kitchen extractor unit will need an isolator switch fitting
b) Our CU is about 7 years old (replaced the old fusebox when we moved in) and has MCB's, but electrician says we will need to have RCD MCB's fitted or a single main switch RCD fitted (don't like that idea!).

Q's:

a) Can the isolator switch be fitted in the loft or does it HAVE to be in the kitchen?
b) Is this correct? - I might as well have a (yet another!) new CU fitted as he says individual RCD MCB will be about £30 a pop and we need three...

 

[PrenticeBoyofDerry]

a) Kitchen extractor unit will need an isolator switch fitting

The manufacturers instruction will very likely recommend this, ans Yes, what use would it be in the loft?

b) Our CU is about 7 years old (replaced the old fusebox when we moved in) and has MCB's, but electrician says we will need to have RCD MCB's fitted or a single main switch RCD fitted (don't like that idea!).

Circuits with newly installed sockets on and circuits that have cable buried within wall less than 50mm that is not mechanically protected will require 30mA RCD protection, so if the fuse board/CU will take RCBOs then that is the way to go rather than a single RCD/RCCB switch.
Depending on the make model of board would dictate price of RCBOs as the vary from £12.00-£40.00+

 

[JohnW2]

a) Kitchen extractor unit will need an isolator switch fitting
b) Our CU is about 7 years old (replaced the old fusebox when we moved in) and has MCB's, but electrician says we will need to have RCD MCB's fitted or a single main switch RCD fitted (don't like that idea!).
...a) Can the isolator switch be fitted in the loft or does it HAVE to be in the kitchen?
b) Is this correct? - I might as well have a (yet another!) new CU fitted as he says individual RCD MCB will be about £30 a pop and we need three...

(a)...the regulations per se don't require an isolator at all. However, if the instructions provided by the manufacturer of the extractor call for an isolator, then the regs require that those instructions be followed. However, I don't recall having seen any such instructions which say where the isolator has to be located!

(b)...any new sockets or any circuits involving buried cables will normally require RCD protection. The 'RCD MCBs' you mention are normally called RCBOs - although much more expensive than MCBs they do have some advantages (mainly that a fault will only take out one circuit, not several). A new CU with just a single RCD, such as you mention, would be considered by most people as not being compliant with current regs.

Kind Regards, John

 

[bernardgreen]

Consider what you will do if a grease impregnated filter in the extractor catches fire. Cooking flambe or a fire in the frying pan can ignite a well used filter

If the extractor is extracting out of the building then the fanned flames will be blown out outside. That is assuming the ducting is fire proof and not easy to melt plastic.

But if the "extractor" is a recycling hood then the flames and fumes are pushed out into the kitchen

Stopping the fan is one of the rapid response actions needed, so where should the isolator be if the flames prevent you getting to the hoods control panel ?

 

[AndyPRK]

Could you post a pic if your cu

Why do you need rcbos? Aren't the kitchen circuits already on the rcd side?

Or are you adding new circuits.

 

[JohnW2]

Why do you need rcbos? Aren't the kitchen circuits already on the rcd side?

Surprising though it may be (for a CU installed 7 years ago), it sounds as if the OP's current CU may not have any RCD protection - since one of the solutions he was contemplating (which, as I said, most would regard as non-compliant) was to replace the CU with a single-RCD one.

Kind Regards, John

 

[PrenticeBoyofDerry]

Could you post a pic if your cu

Why do you need rcbos? Aren't the kitchen circuits already on the rcd side?

Or are you adding new circuits.

As John has mentioned the OP seems to indicate that there is no RCD protection on this board.

 

[ban-all-sheds]

Our CU is about 7 years old (replaced the old fusebox when we moved in)

And you ended up with one without an RCD?

Where did you find that useless electrician? B&Q?

In 2007 RCD protection for sockets likely to be used to supply portable equipment out doors had been a requirement for several years, and the draft of the 17th Edition of the Wiring Regulations was already out, so it was known that you'd need RCDs for all sockets, for concealed cables etc in 2008.

You really were badly advised and badly served by that negligent unprofessional fool.

 

[DaftPunk]

No RCD was perfectly fine under the 16th edition.

Wind your neck in.

 

[JohnW2]

Consider what you will do if a grease impregnated filter in the extractor catches fire. Cooking flambe or a fire in the frying pan can ignite a well used filter ... If the extractor is extracting out of the building then the fanned flames will be blown out outside. That is assuming the ducting is fire proof and not easy to melt plastic. ... But if the "extractor" is a recycling hood then the flames and fumes are pushed out into the kitchen

That's all true if it is a cooker hood (and, as you say, probably only a major issue if it's a recirculating one) we're talking about, but I'm far from sure that one can assume that from the 'extractor' description.
rjb2001: What exactly is this 'extractor'?

Stopping the fan is one of the rapid response actions needed, so where should the isolator be if the flames prevent you getting to the hoods control panel ?

To be pedantic, you're talking about an 'emergency switch', rather than an 'isolator' - and I have to say that I've seen few located in such a position that I would want to try to operate it if the associated cooker hood was spewing flames! In most ordinary houses, the CU is pretty (often very) close to the kitchen, and that represents an easy (and safe) method of disarming the electrical supply to the hood (or whatever).

Kind Regards, John

 

[AndyPRK]

Would be nice to see a pic of the Cu rather than guess.

 

[JohnW2]

No RCD was perfectly fine under the 16th edition. Wind your neck in.

No-one is denying that a non-RCD CU was compliant with 16th ed., so long as any sockets likely to be used for outside equipment was separately RCD-protected. However, I would think that most of us would agree with BAS that no sensible electrician would have advised the installation of such a CU in 2007. (of course, the customer may have ignored 'sensible advice' and insisted on such a CU!. I certainly had CUs with RCDs (global RCD and/or 'split-load') long before 2007.

Kind Regards, John

 

[bernardgreen]

In most ordinary houses, the CU is pretty (often very) close to the kitchen, and that represents an easy (and safe) method of disarming the electrical supply to the hood (or whatever).

Using the CU would require either turning of the main switch and losing all power and lights or spending time finding which MCB was the one for the cooker hood.

Evacuating a house at night without lights is a very hazardous process. Especially if there is smoke and fire in the kitchen.

I agree the word "isolation" does not infer any use as an emergency isolator.
Perhaps the manufacturers should refere to it as an "emergency cut off" but that would infer the appliance could create an emergency, that would be bad for sales.

 

[rjb2001]

Thanks for the replies but jeez, calm down guys!

When we got the house it had a old brown fuse box; part of the surveyors notes was this needed replacing, got an electrician in and this is what was installed:

The extractor/cooker hood is going to be ducted outside - do these hoods often bust into flames and spew fire everywhere? Sounds like they should be banned!

 

[JohnW2]

Using the CU would require either turning of the main switch and losing all power and lights or spending time finding which MCB was the one for the cooker hood.

True - but (assuming they were labelled!) the one labelled 'kitchen sockets' might be a reasonable bet and, if that didn't work, the one labelled 'cooker'! By the same token, it's not at all unlikely that a person would have some difficulty locating the correct 'emergency cut off' switch in the kitchen, particularly if it were surrounded by smoke and/or flames at the time!

I agree the word "isolation" does not infer any use as an emergency isolator. ... Perhaps the manufacturers should refere to it as an "emergency cut off" but that would infer the appliance could create an emergency, that would be bad for sales.

I suspect they are just 'set in their ways' - the manufacturers of bog standard ('bathroom/kitchen/loo') extractor fans (and, don't forget, that might be what we're talking about) seem obsessed with the need for 'isolators' - even in situations in which the true need for an 'emergency cut off' would be incredibly rare.

Kind Regards, John