The 100A sticker doesn't mean there is a 100A fuse in it.
Sanity Check Required - Do I really need 3 Phase Upgrade?
- Thread starter philnixon
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Well, one has to believe some things - and "100A Fuse Fitted" seems about as clear as it could possibly be!
Whatever, I think the OP's proposed installation would probably be fine with an 80A cutout fuse, don't you?
Kind Regards, John
Oh, beg pardon, I didn't look.
I just thought it was the usual sticker which just means the carrier is rated at 100A.
I just thought it was the usual sticker which just means the carrier is rated at 100A.
That's not what is says! The carrier/housing will probably have the 100A maximum rating moulded onto it somewhere - but the "100A Fuse Fitted" sticker surely could not be any more clear/explicit if it wanted to be?
IMO, if anyone left that "100A Fuse Fitted" sticker on it after having just installed a fuse other than 100A, they are a bit daft and/or irresponsible. In reality, I would imagine that they probably applied the sticker at the time they installed a 100A fuse.
Kind Regards, John
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Yea, I found one of WPDs sticker sets left over in a new cutout recently.
It had a nice selection of L1,L2,L3&N markers, 415/230v stickers and it had a selection of fuse carrier labels, 60/80/100A, also had the BS number for the fuses, so I would suspect there's no excuse to put the wrong sticker on. Probably something they could get disciplined for
It had a nice selection of L1,L2,L3&N markers, 415/230v stickers and it had a selection of fuse carrier labels, 60/80/100A, also had the BS number for the fuses, so I would suspect there's no excuse to put the wrong sticker on. Probably something they could get disciplined for
Quite so - as I said a "100A Fuse Fitted" sticker is so explicit that anyone who puts it on (or allows it to stay on) when they've just fitted a fuse other than 100A really should not be doing that job!
Kind Regards, John
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... but I don't think we are, after diversity. As I said to the OP, there probably aren't that many installations for which adding up all the potential 'maximum loads' would not produce a figure in excess of the rating of the cutout fuse. Don't forget that the DNO would probably regard the average load of the OP's installation (apply the sort of diversity that they do) as about 10A !!But don't tell Ban that we're advising putting a 100A+ load onto a 100A fuse......
Kind Regards, John
No, we're not, I agree with you 100% there.
It was just a dig at Ban after saying you couldn't put a 26A load on a 20A breaker.
I realise that - but, to be fair to BAS, we're talking about different things. I agree with him that it would be wrong (and non-compliant) to have circuit with a design current of 26A protected by a 20A device. It would also be wrong to have an installation with a "design current" of >100A protected by a 100A fuse. However, in determining the "design current" of an installation, all sorts of diversity can be applied (hence, IIRC, DNOs regard the average house as representing a 'design load' of ~2.5kW, aka a "design current" of ~10A).
Kind Regards, John
Even here in areas where homes have electric cooking and substantial size air-conditioning and/or electric heating, a 100A service for a house of 1500 to 2000 sq ft. or so is not at all uncommon. But we do have the advantage that the main fuse/circuit-breaker is part of the customer's installation, so easily replaced/reset even if it does trip.
It's surprising just how much people can get away with in terms of low-rated services. What must be 10 to 15 years ago now, I got asked to look at the wiring in an old three-story Victorian house which had been used as a seaside guest house for a few years. As best as I can recall now, there were about three instant electric showers, an electric immersion heater, although probably not much used as there was a gas boiler as well, individual wall heaters probably about 750 - 1000W each in about five or six bedrooms, and they had an electric cooker as well. I remember the whole lot was running on an old 30A service - Rewireable fuse inside the cut-out no doubt, which would take a considerable short-term overload.
It's surprising just how much people can get away with in terms of low-rated services. What must be 10 to 15 years ago now, I got asked to look at the wiring in an old three-story Victorian house which had been used as a seaside guest house for a few years. As best as I can recall now, there were about three instant electric showers, an electric immersion heater, although probably not much used as there was a gas boiler as well, individual wall heaters probably about 750 - 1000W each in about five or six bedrooms, and they had an electric cooker as well. I remember the whole lot was running on an old 30A service - Rewireable fuse inside the cut-out no doubt, which would take a considerable short-term overload.
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If a 3036 it would need a 60A load to blow instantaneously.
Hence why I suspect it was that and not a cartridge fuse - Or they were just very fortunate with diversity in their guests' usage! I
Pathetic.we're not, I agree with you 100% there.But don't tell Ban that we're advising putting a 100A+ load onto a 100A fuse......
It was just a dig at Ban after saying you couldn't put a 26A load on a 20A breaker.
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What is?
I don't agree about the 20A breaker scenario.
A 20A radial on 2.5 is a standard circuit. Of course it could be subject to 20+A of loading, just as a 32A ring final could have 32+A plugged into it.
I don't agree about the 20A breaker scenario.
A 20A radial on 2.5 is a standard circuit. Of course it could be subject to 20+A of loading, just as a 32A ring final could have 32+A plugged into it.
I think it really comes down to what the designer feels is the "design current". In the absence of any information about how the circuit will be used/loaded, the convention is to consider the design current of a sockets circuit to be the In of its OPD - even tghough, as you say, it's far from impossible that a greater load than that will be 'plugged in'. However, IF the designer knows, or has reason to consider 'likely', that the loading on the circuit will sometimes be some figure greater than, say, 20A, then I would say that that 'figure' becomes the "design current", so that a 20A OPD (and perhaps not 2.5mm² cable) would not be appropriate.
Kind Regards, John
Thanks all,
Looks like I will have to try once more to see if I can change my electrician's mind. It's a bit annoying as this only came to light after first fix was almost complete. It's not my choice of electrician - it's one of the people my "project manager" usually uses. Project manager in quotes as he seems to have no knowledge related to these technical things, just likes to do the design aspect! The cable runs have now been over-boarded so changing electrician at the stage could be painful.
Regards,
Phil
Looks like I will have to try once more to see if I can change my electrician's mind. It's a bit annoying as this only came to light after first fix was almost complete. It's not my choice of electrician - it's one of the people my "project manager" usually uses. Project manager in quotes as he seems to have no knowledge related to these technical things, just likes to do the design aspect! The cable runs have now been over-boarded so changing electrician at the stage could be painful.
Regards,
Phil
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