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D

DuncanS

Here's a scenario, I'm adding two new circuits to a mini consumer unit for my first ever NAPIT inspection... Just noticed that the main switch/RCD is rated to 100amps but the suppliers main fuse is only 80amp, should I change the RCD to one that's 80amp or lower, I don't want the NAPIT spark to think I've over looked anything...
just to add detail the circuits on the board are as follows, oven 32amp breaker! shower 45amp breaker, jacuzzi 20amp breaker.
 
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[QUOTE MDJ] Nope there are others fighting for his crown, at least one banned for it recently as well LMAO[/QUOTE]

Ah yes I remember your little forced vacation from the forum.
Have you applied for the position of official forum troll or are you just practicing first.
I think you do need a certain level of articulation and knowledge of the appropriate subject to be a credible troll on any forum though. Bad luck on both counts.
LMFAO

: ) ; )
 
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NickD said:
(Just dealing with the reality of the way the world is rather than the way we think it ought to be for a second, the guy is here and is asking the question. Does it make more sense to rip the guy to shreds or to respond in a civilised way?)

Duncan, does the 100A rating of the main switch/RCD mean "I can routinely carry up to 100A load current" or "I will detect an overcurrent and disconnect if I carry above 100A"? Answer almost certainly the first but it's down to you to check that. It is quite a basic distinction that you should be aware of to practice competently. Good luck with the assessment.
Click to expand...

It can routinely carry 100a, which was my concern in the first place, because if some spark has put this in some time ago and, there I go drawing 100a through it I'm gonna blow the main fuse, which would be a bugger as the DNO get funny about people just replacing them, no?
I appreciate those of you with sensible replies, for the trolls, let me remind you that once you were new to this and for me this is the first install I've done unsupervised so please do excuse my nerves, I'd rather come on here and double check my worries than leave something unsafe...
 
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DuncanS said:
It can routinely carry 100a, which was my concern in the first place, because if some spark has put this in some time ago and, there I go drawing 100a through it I'm gonna blow the main fuse, which would be a bugger as the DNO get funny about people just replacing them, no?
Click to expand...

But it is rated for up to 100A which is fine; the DNO fuse is lower and so protects it. It is not the job or concern of the main switch to limit the current to something that will prevent the DNO fuse from blowing. It is the collective job of the installation design and the overcurrent devices which are downstream from the main switch, allowing for diversity because bearing in mind on virtually any installation if all the protective devices were carrying all of their rated maximum current at once it would blow the DNO fuse. My install here has 3 x 30A, 6 x 15A and 1 x 5A fusebox fuses for example, theoretical maximum draw 185A, on a 60A DNO fuse.
 
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NickD said:
But it is rated for up to 100A which is fine; the DNO fuse is lower and so protects it. It is not the job or concern of the main switch to limit the current to something that will prevent the DNO fuse from blowing. It is the collective job of the installation design and the overcurrent devices which are downstream from the main switch, allowing for diversity because bearing in mind on virtually any installation if all the protective devices were carrying all of their rated maximum current at once it would blow the DNO fuse. My install here has 3 x 30A, 6 x 15A and 1 x 5A fusebox fuses for example, theoretical maximum draw 185A, on a 60A DNO fuse.
Click to expand...

Thanks, as you can tell I didn't install this unit just adding another two circuits... I'm probably over thinking things and just being paranoid but.... If this unit is protected by an rcd, does that rcd effectively become it's main switch? Or should it have a separate one as the mini consumer unit is not fed by the main consumer unit, like I say I didn't install it but I wouldn't like to assume some one else did a good job when it's me being assessed... In school we always would start with a dp switch and work along from there...
 
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DuncanS said:
It can routinely carry 100a, which was my concern in the first place, because if some spark has put this in some time ago and, there I go drawing 100a through it I'm gonna blow the main fuse, which would be a bugger as the DNO get funny about people just replacing them, no?
I appreciate those of you with sensible replies, for the trolls, let me remind you that once you were new to this and for me this is the first install I've done unsupervised so please do excuse my nerves, I'd rather come on here and double check my worries than leave something unsafe...
Click to expand...
just caus a fuse`s I N rating is ...say in this case 100A...doesn`t mean that it will let go at 100A

further more i`d love to see a domestic installation that got anyware near 80A..never mind 100A....

theres such a thing as diversity as well...
 
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