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No. But someone else might...
Extended ring circuit
- Thread starter Milleniumaire
- Start date
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Thanks, I did look for the actual wattage of the shower unit, but obviously not as thoroughly as you did
Yes, quite often I'm in the shower while my wife is drying her hair, which can take hours!
In fairness his point was valid nonetheless, which is that simply adding all loads together does not tell us what to expect in the real world.
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But proving worst case that a 20 or 25A Mcb would be fine !
I'll be honest - I don't understand the fascination with 16A radials over 20A radials.
25A circuit breakers are less common (although Hager and others do produce them). That said, there are circumstances where it wouldn't be appropriate to use a 25A circuit breaker, so 20A would certainly be the more conventional approach.
Here, the very basic standard approach with radial final circuits would be:
1.5mm^2: 10A MCB
2.5mm^2: 20A MCB
4mm^2: 25A MCB
6mm^2: 32A MCB etc.
25A circuit breakers are less common (although Hager and others do produce them). That said, there are circumstances where it wouldn't be appropriate to use a 25A circuit breaker, so 20A would certainly be the more conventional approach.
Here, the very basic standard approach with radial final circuits would be:
1.5mm^2: 10A MCB
2.5mm^2: 20A MCB
4mm^2: 25A MCB
6mm^2: 32A MCB etc.
Why are you using oversized cables (or lower rated MCBs) for all your suggestions?
I'm not making suggestions. I simply stated that the standard rule of thumb in Ireland is as described. And they are not all oversized. As I pointed out, 2.5mm^2 isn't always suitable on a 25A device. Nor is 4mm^2 always suitable on a 32A device, etc.
Then please go to Electrics outside of the UK
Yes they are.
When is it not?
When is it not?
True, in neither case will such cable/OPD combinations 'always be suitable'. However, although 'not always suitable', they very commonly 'will be suitable'. It therefore seems odd that a 'rule of thumb' should be based on an unusual 'bad case'. Are electricians in Ireland not encouraged to think and apply knowledge?
In fact, as far as I can see, even those rules of thumb will not always be correct - since, in the worst case scenarios, even thouigh cables would be uynder-sized - again, there is a need to think, rather than hope (incorrectly) that the 'rule of thumb' is a 'one size fits all' solution which removes the need for any thopught or knowledge.
Kind Regards, John
I would suggest that 4mm^2 is actually seldom suitable for a 32A protective device. The circumstances where it is suitable are quite limited.
Methods 100, 101, 102 & 103 for a start, and maybe with other de-reating factors.
However, as I've just written, I would say that it's far better to think than to rely on a rule of thumb which is based on a relatively uncommon 'bad' (but not 'worst') case scenario.
Kind Regards, John
Don't be silly John.
I would suggest that it is British Electricians who think that 1.5mm^2 lighting circuits on 6A circuit breakers or 2.5mm^2 radial circuits on 16A circuit breakers (other than for the likes of an immersion heater) are sensible solutions who are incapable of intelligent design.
You will note that I have not promoted following "rules of thumb". I simply pointed out that the Irish rules of thumb may be more sensible than the British equivalent rules of thumb.
Personally I promote intelligent design based on the merits of what is there.
Well, I have to admit that I haven't a clue as to what goes on in Ireland, but 'over here' Method C cable installation without de-rating factors seems common, rather than the 'quite limited' which you appear to be saying is the case in Ireland. Why are the Irish practices different?
Kind Regards, John
Clipped direct is not uncommon per se in domestic installations. However more and more there is a mix in installation methods through an installation.
And don't forget that no-one here ever caps cables down walls - round conduit is always used - and that is true on both sides of the border.
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