Urgent Electric Problem

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typed:

http://electrical.about.com/od/panelsdistribution/qt/electricmetermeasurements.htm
An interesting point there - 'large capacitor banks...'
Over here IME most power factor correction is done directly on the equipment so the power factor demand on the incoming supply will stay pretty much the same irrespective of load - which it would probably not in your instance.
--
Woody

harrogate three at ntlworld dot com
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UK plugs only recently had plugs mandatory fitted. - Before then bare wires (perhaps with a bootlace ferrule) were the norm and a person had to wire a plug following instructions on a card pushed over the plug pins. - Such plugs almost exclusively came supplied with a 13A fuse prefitted until relatively recently. - Thus many appliances had a power cord which might not be sized correctly for a 13A fuse.
The EU mandated that all appliances be supplied with a pre-fitted plug. This was a way around supplying all appliances with a power cord sized to handle all fault currents which would be unwieldy for small table lamps or standard lamps with long power cords.
Yes some people do know there are 1 3 5 7 10 13A fuses available, however 1A are not for BS1363(/A) plugs - they were for dedicated clock plug/socket (you know, the b@stards with bare brass knurled terminals at the rear fed by bell wire that threw you across the room) and perhaps shaver adapters. However if you DID check the UK I am willing to bet over 90% have a 13A fuse in them - a) that came with the plug b) that was all they had left when the last 3A fuse was used up c) not knowing any different d) not paying 3 for a pack of 3A or 5A e) assume the MCB will beat the fuse for disconnection of most faults f) can't remember the last time they had to replace a fuse.
A typical BS1362 cartridge fuse will disconnect at 7-10* In (where In is the fuse rating). Thus a 3A fuse will disconnect instantly at 21-30A and a 13A fuse will disconnect instantly at 91-130A. A Type-B circuit breaker will trip <0.1sec at 5*In which is 80A, 100A & 160A for 16A, 20A & 32A In rating (radial, radial, radial/ring) - with <0.1sec being faster than a fuse.
The problem comes when you have appliances such as hedge trimmers used on very long power cords of small conductor size, which are then plugged into a long extension lead. The result is a very high L-E & L- N resistance, L-E fault is handled by an RCD/RCBO which trips at typically 30mA thus also handling electrocution, L-N can not be handled in this way with the result that the cable can overheat until a fault is disconnected.
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with bare brass knurled terminals at the rear fed by bell wire that threw you across the room) and perhaps shaver adapters. However if you DID check the UK I am willing to bet over 90% have a 13A fuse in them - a) that came with the plug b) that was all they had left when the last 3A fuse was used up c) not knowing any different d) not paying 3 for a pack of 3A or 5A e) assume the MCB will beat the fuse for disconnection of most faults f) can't remember the last time they had to replace a fuse.
A typical BS1362 cartridge fuse will disconnect at 7-10* In (where In is the fuse rating). Thus a 3A fuse will disconnect instantly at 21-30A and a 13A fuse will disconnect instantly at 91-130A. A Type-B circuit breaker will trip <0.1sec at 5*In which is 80A, 100A & 160A for 16A, 20A & 32A In rating (radial, radial, radial/ring) - with <0.1sec being faster than a fuse.
The problem comes when you have appliances such as hedge trimmers used on very long power cords of small conductor size, which are then plugged into a long extension lead. The result is a very high L-E & L- N resistance, L-E fault is handled by an RCD/RCBO which trips at typically 30mA thus also handling electrocution, L-N can not be handled in this way with the result that the cable can overheat until a fault is disconnected.
Thank you for your support both (a) in fuses sizes available and (b) the attitude and lack of knowledge/understanding of the general British Public. It is not nice to get flamed (if only in part) when you know you are right, if if the comment is subjective!
--
Woody

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with bare brass knurled

Hi guys,
This is the point that I started getting confused, what is so different about a 1 amp BS1362 fuse, as opposed to a 3amp BS1362 fuse (apart from the current rating of course), that I cannot put it into a BS1363 mains plug. They seem to be the same length, and diameter so they should fit, and they have the same voltage rating, maybe something to do with the disconnection time of current ? I remember fitting 1 amp fuses to plugs years ago. Farnell even have them for sale, see http://uk.farnell.com/bussmann/c180-1/fuse-quick-blow-1a-bs1362/dp/1123029 , so what is the problem ?
I really am interested in this and I am not trying to start a Flame war !!!
Ian.
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with bare brass knurled

1A fuses are not ASTA certified.
Nice video of a fuse (not a 1A fuse) failing a test below.
http://www.era.co.uk/services/devices.asp
And a good debate is better than a flame war.
Adam
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with bare brass

Interesting. The CPC catalogue indicates that they are?
And thank you for those that now agree with me when others said you cannot use 1A BS1362 fuses in BS1363 plugs. I remember using them in the 60's and 70's!!!
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Woody

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with bare brass knurled

Hi Adam,
Yes, I see that now that I look closer, however, is it a requirement that a fuse is ASTA certified ?
I see in the BEAMA document http://www.beamainstallation.org.uk/assets/pdfs/SwitchFusegearDevices.pdf that fuses have to be to BS1362 but it makes no mention of ASTA.
Ian.
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with bare brass knurled

It would be a PAT test failure.
Adam
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On Fri, 1 Jan 2010 18:12:59 -0000, Ian French wrote:

Same here - all of my soldering irons have 1A fuses; I use 2, 3, 5, 7 10 and [a few] 13A as well. Been doing this for 30 years or more! Have I been lucky with the 1A?
--
Peter.
2x4 - thick plank; 4x4 - two of 'em.
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In with bare brass knurled

That's a pretty thorough, consice response; thanks much. A lot of our GFCI's, interestingly enough, will in fact trip if there is a Neutral/Earth fault as in a neutral short to earth ground or a miswire. I discovered this at: http://www.rhtubs.com/GFCI/GFCI.htm as I wasn't aware of it. I forget the current differential a GFCI trips at, I -think- it's 5 mA, but the link above recommends using 7 mA for testing, which should always open the ckt. This one says 4-5 mA and 1/30 second: http://home.howstuffworks.com/question117.htm
And if you're intrested at all, here's one that talks about both sides of the pond: http://en.wikipedia.org/wiki/Residual-current_device
I've learned a few things today; guess I can relax now<g>!
Twayne
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In typed:

That's interesting and makes a LOT of sense! I suppose that could be happening here, but I didn't come across it yet. I've been out of the business for a decade now so lots of things have changed. Who would do the approvals for such a piece of equipment that includes onboard PF correction? I'm familiar enough with a lot of the UK (which I assume "over here" refers to) and even some EU/ET etc. or whatever it's called these days, rules & regs to be able to compare them to our rules & regs. I'm thinking it would have to be the power company themselves, or the grid supplier maybe. Think I'll go look at some large industrial machines sales maybe<g>. You got me real curious!
Cheers,
Twayne
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check any fans in toilets/bathrooms etc especially if they have run on timers. good luck cj

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