Safe zones and fixed appliances

[jabuzzard]

Does a fixed appliance in this case a chimney extractor hood create a safe zone?

What I propose to do is run a length of flexible conduit vertically up from a back box which is located to the side of the hob position to level where it will need to emerge from the wall for the hood doing the right angle bend within the width of the back box. The idea being that I can run some flex through to the back box and put an appropriately fused 13A fused connection unit in. The circuit is protected by an RCD.

Clearly from a practical perspective it will work, but will the installation be within the rules, as I cannot see anything in the regulations that would suggest that fixed appliances create safe zones in the way sockets and switches do and running metal conduit for a extractor hood seems like overkill to me?

If it is not within the regulations what is the accepted way to get the power to a cooker hood so there is no visible flex?

Note for the avoidance of any doubt I am in Scotland so Part P does not apply.

 

[EFLImpudence]

Will you not have a flex outlet plate near the hood?

 

[RF Lighting]

Fit a socket behind the chimney. This creates a horizontal safe zone.

Then you may go vertically from the FCU, and turn at a right angle to go horizontally into the socket.

It also makes it easier to put up / take down the hood if it just plugs in.

 

[jabuzzard]

Will you not have a flex outlet plate near the hood?

That would then be visible, with cable dangling between the flex outlet plate and the hood. I am thinking of a chimney hood, something like this

http://www.currys.co.uk/gbuk/hotpoint-he6tix-chimney-hood-stainless-steel-11418696-pdt.html

rather than the more traditional integrated hood

http://www.currys.co.uk/gbuk/indesi...cooker-hood-stainless-steel-18019183-pdt.html

My idea was to run some smooth walled flexible conduit from a fused switched flex outlet (specifically an MK K330) up vertically then horizontally coming out the wall behind where the hood is to be fixed. To wire in the hood one then just pushes the flex for the hood down the conduit crimp some boot lace ferules on the end and terminate in the switched fused spur outlet and fit an appropriate fuse. The boiler is wired similar to this except the conduit does not bend through 90 degrees. It just runs straight from the fused switched outlet coming out just below the boiler.

I guess I could run to a unswitched fused outlet plate above the cupboards and then run conduit to the back of the chimney bit of the extractor hood. I have to say that just seems to introduce another point of failure for no real benefit.

 

[ban-all-sheds]

I cannot see anything in the regulations that would suggest that fixed appliances create safe zones in the way sockets and switches do

I'm inclined to agree.

and running metal conduit for a extractor hood seems like overkill to me?

But seriously - it doesn't matter whether it's a cooker hood or a restaurant sized cooker - the dangers of concealed cables are not related to the current which the load draws.

If it is not within the regulations what is the accepted way to get the power to a cooker hood so there is no visible flex?

Fit a socket behind the chimney. This creates a horizontal safe zone.

Then you may go vertically from the FCU, and turn at a right angle to go horizontally into the socket.

but that always seemed a bit dodgy, to me, which is why I chose the steel conduit solution.

If you think about why the regulation says what it does about zones in relation to accessories it's all about being able to know that there might be cables buried there because you can see the accessories. But if you then conceal the accessory, IMO you lose the zone which only existed because you could see that there was an accessory there.

Note for the avoidance of any doubt I am in Scotland so Part P does not apply.

Should still be safe though.

 

[rjm2k]

I'm sure I've seen this before and the solution was to add an empty back box and blank face next to the hood into which you run your cable and do the 90 degree turn then out again.

Even though there's nothing happening in the box (and therefore no extra point of failure), the presence of the box extends the safe zone both vertically from your FCU and horizontally to the appliance?

 

[JohnW2]

I'm sure I've seen this before and the solution was to add an empty back box and blank face next to the hood into which you run your cable and do the 90 degree turn then out again. Even though there's nothing happening in the box (and therefore no extra point of failure), the presence of the box extends the safe zone both vertically from your FCU and horizontally to the appliance?

Yes, I've seen that done, and it seems sensible. However, I wonder if a blank plate really does create safe zones in the eyes of the regs - that all depends upon whether the regs consider a blank plate to be a "point, accessory or switchgear" [522.6.101(v)], and I'm not at all sure about that. I guess that, if one were concerned, one could use a (unconnected) switch or socket, rather than a blank plate.

Kind Regards, John

 

[EFLImpudence]

Fit a socket behind the chimney. This creates a horizontal safe zone.

Then you may go vertically from the FCU, and turn at a right angle to go horizontally into the socket.

but that always seemed a bit dodgy, to me, which is why I chose the steel conduit solution.

If you think about why the regulation says what it does about zones in relation to accessories it's all about being able to know that there might be cables buried there because you can see the accessories. But if you then conceal the accessory, IMO you lose the zone which only existed because you could see that there was an accessory there.

That's a fair point but not really any different than socket/outlet for a built in appliance.

 

[ban-all-sheds]

Depends which way the cables run.

If they drop down the walls then I would likewise not want to see them directly buried on the basis that sockets below the worktops create safe zones.

 

[JohnW2]

Depends which way the cables run. ... If they drop down the walls then I would likewise not want to see them directly buried on the basis that sockets below the worktops create safe zones.

That makes total sense in terms of the assumed spirit of the regs, and common sense safety considerations. However, as so often, the authors have not thought carefully enough about the 'words' of the regs, which say nothing about an accessory etc. having to be visible in order to create safe zones!

Kind Regards, John.

 

[RF Lighting]

and running metal conduit for a extractor hood seems like overkill to me?

Madness. You'd never catch me doing that.

Oh hang on...

 

[jabuzzard]

If you think about why the regulation says what it does about zones in relation to accessories it's all about being able to know that there might be cables buried there because you can see the accessories. But if you then conceal the accessory, IMO you lose the zone which only existed because you could see that there was an accessory there.

Is there a definition of what an accessory is? I can't see one but I only have a copy of the 16th edition. However playing devils advocate would one consider a wall mounted light fitting such as an uplighter or spotlight an accessory?

Given that all such lighting as this that I have ever seen has buried cabling I am going to work on the presumption that it must surely be considered an "accessory" and create a safe zone as I strongly suspect that only a tiny majority of it is in steel conduit.

There must also be millions of electric showers with buried cable as well, so presumably a shower counts as an "accessory" too. I could go on with a long list of wall mounted electrical items that don't fit in a back box that are clearly considered "accessories".

So in these circumstances surely a fixed wall mounted chimney cooker hood is an "accessory" and creates an admittedly rather large safe zone?

Of course it has since occurred to me that I can side step this all this through the use of BS8436 cable, and given I have found a supplier selling it by the metre that is the route I shall go.

 

[EFLImpudence]

Accessory - A device, other than current-using equipment, associated with such equipment or with the wiring of an installation.

 

[JohnW2]

Is there a definition of what an accessory is? I can't see one but I only have a copy of the 16th edition. However playing devils advocate would one consider a wall mounted light fitting such as an uplighter or spotlight an accessory?

As you say, interesting question. As I wrote earlier in this thread:

... However, I wonder if a blank plate really does create safe zones in the eyes of the regs - that all depends upon whether the regs consider a blank plate to be a "point, accessory or switchgear" [522.6.101(v)], and I'm not at all sure about that.

In answer to your question, Part 2 of the current regs defines 'an accessory' as "A device, other than current-using equipment, associated with with such equipment or with the wiring of an installation". In terms of your question, that exclusion of current-using equipment could be very restrictive, unless one felt that the casing/enclosure of such equipment qualified (per the regs' very vague definition!) as an 'accessoiry'!

Furthermore, as I noted earlier, the regs don't say anything about an accessory having to be visible to create safe zones (which, as BAS said, is a bit daft).

Kind Regards, John

 

[EFLImpudence]

The regulations actually state "point, accessory or switchgear".

So, I would assume a zone would be created by the cable merely emerging from the wall rather than the whole area covered by the hood.

I would still fit a connector plate behind the chimney.