cooker hood off 32A 4mm radial "spur"

I've decided the best way to connect my cooker hood is via a "spur" off the 32A 4mm radial for fixed appliances. Is it OK to create a spur using an inaccessible-type junction box (not plastered in, just behind some units) rather than at a socket ? Can't think why not, but y'know best to check. Any limit to the length of "spur" ? Simon.
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Sorry, forgot to say, the wiring at that point is behind units, but all surface wired. The wiring will go from surface wired to buried in a horizontal line with an FSU that will be just above the wall units, so not visible from most positions. Simon.
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On 12/04/2011 18:50, sm_jamieson wrote:

Yup, sounds ok. Spur can be in 2.5mm^2 T&E, and you probably need the SFCU fused at 3A - but follow the cooker hood instructions on that.
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Well that advice (although sound) is just the sort of thing that will give Dennis a heart attack.
I would not actually be happy with a junction box behind kitchen units if it is only a few feet to the nearest socket.
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On 12/04/2011 21:17, ARWadsworth wrote:

I have misplaced my "clue by four", so I can't give him a smack with it...

Indeed - at a socket (FCU etc) would be best (assuming its a socket circuit!)
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wrote:

Why would it be better, you both claimed that the spurs are perfectly safe.
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Do you ever read what you have written before pressing the send button?
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Too thick to understand what I say are you?
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As your comment was not relevant to John's point then I suggest that you are the thick one.
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So you are too thick.
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On 12/04/2011 22:59, dennis@home wrote:

Non sequitur...
<rummage> Ah, found it! Come 'ere you dozy twonk... <fx whoosh, whack, Owwww>
It would be better to originate your spur from an existing accessory that is to remain visible such as a socket or a FCU etc, rather than originate it from a concealed junction box. This is assuming the JB is a screw connection type that should remain available for inspection. If using a maintenance free JB then that is a different matter. The issue at hand is whether the junction box remains accessible, and has absolutely nothing to do with spurs.
The spur would obviously be perfectly safe (yes even to you denis), since it would not be feasible to overload a 2.5mm^2 cable via a single fused connection unit (and certainly not with a cooker hood), and the cable would be more than adequately fault protected by a B32 MCB at the origin of the circuit.
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I tried to say that in the OP, but used the wrong terminology. I said "inaccessible-type junction box". I should have said "maintenance free". Which kind of shifts the argument. The debate is then between a maintenance free junction box when the spur could reasonably be taked from a nearby socket (even if you have to run horizontally a bit further to reach the socket). This makes the argument about spurs, and not about accessible junction boxes ;-) Simon.
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On 12/04/2011 23:43, sm_jamieson wrote:

Indeed. However if you already have a close by accessory, then there is not much to be gained from adding an extra JB other than cost.
(Although wago push wire terminals in an empty box may be easier to use with a larger number of stiff wires - so probably easier to wire a branch (i.e. 4mm^2) rather than at a socket).

Well there is nothing to argue about when the spur is feeding a single FCU and nothing else - even in dennis land ;-)
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John.

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Well at least you realise that you have to qualify what the load is to "know" its safe, that's progress I suppose. Unlike the situation where somebody can plug in a four way and overload the circuit without you having any control over the load on the installation you did.

Ah those words again, "adequately fault protected" but not against overload (strange that that isn't a fault?) should someone put a 13A socket on a 2.5 mm spur and then plug in a four way. I do like the words electricians use when they blame the user for overloading their "perfectly protected" installations, they are usually something like "well they shouldn't do that", "f'ing idiots", "everybody knows that you can overload a socket without the fuse ever blowing", "they deserve to have killed their family by doing that". All to save a bit of copper.
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A 4-way plug block is fused, and so is an extension lead. Simon.
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Have a look at what current it takes to blow the fuse and note that it is frequently higher than the current rating of 2.5 mm2 T&E and that is before someone has replaced it with a nail because it keeps blowing or has been unfortunate enough to fit a duff fuse like the ones that have been around every few years that don't actually work. I would never rely on a user supplied protection device to protect something I installed as I know the bloody user will screw it up. Some will and argue that they are correct while saying I am wrong even though everything I said to do complies with the same regs they are using to claim they are correct.
You can choose to do either or even do something not in the regs, after all the regs are there to help those that don't actually know what they are doing and provided you do the sums "anything" goes as long as you can prove its safe. Just don't expect the average electrician to have a clue if its not to the regs.
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"> after all the regs are there to help those that don't actually know

Jesus wept. Do you deliberately write this stuff so that people will take the piss out of you?
Now who was it that did not know the regs last time this came up?
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wrote:

I know the bit of the regs you think I don't. I just don't agree with it. I am not alone in thinking this. What's more, I don't have to prove its right as I am not using it.
However its easy to prove the alternative I said is true as in all cases it exceeds the regs. There are no circumstances where it would be wrong to use 4 mm2 cable in place of 2.5 mm2 cable. There are no occasions where it is unsafe to fit a smaller breaker on a 2.5 mm2 circuit. You could even use 2.5 mm2 radials as per the later editions of the regs. These BTW are there to replace rings so even the IEE thinks you are onto a bad thing. Give it a few more editions of the regs and you wont be doing what you are doing now.
Are we going to have the same argument as last time or have you come up with something new and worth listening to? I expect not.
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Of course you now know that bit of the regs. I pointed it out to you last time around around. That is why I said "did not know last time"

Is there a point to those statements?

I will adapt to now regs when they occur in reallty not in dennise world.

You were proven wrong last time.

Why don't you go and set fire to an induction hob?
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wrote:

The only thing you pointed out was that I didn't explicitly state 22A radials and you went on about 30/32A radials which had nothing to do with what I said. But that's typical of you.

Not a chance, you just keep saying that, the reality is different.

That would be hard to do, why don't you tell me the best way?
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