A friend who used to field service cash registers many years ago was called to a takeaway. He noticed they'd cut a hand-sized hole in the middle of the door so they didn't have to keep opening and closing it to stick the pies in...
On 31 Jul 2005 23:00:48 GMT,it is alleged that snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) spake thusly in uk.d-i-y:
[snip]
I meant to stay out of this thread, however, something similar has happened to me while using a hedgetrimmer with a ~50m x 0.75mm sq flex, this being one occasion when such a length is unavoidable in large gardens. Unless we install several outdoor sockets, and this thread really *doesn't* need to get onto outdoor electrics, ring or radial . Cut through the flex part way such that it was jammed in the blades, evidently the short wasn't _short enough_ to blow the 5A plug fuse. Ended up throwing the hedgetrimmer away from me and running to pull the plug, which was hot. Even with the blade of the hedgetrimmer + sparking flex in contact with wet grass, the RCD hadn't tripped either. This is one occasion where the 'circuit breaker plug' proposed elsewhere in this fine thread would be a sensible addition. Possibly with 'arc fault' sensing ability, as now mandated in the US for bedroom circuits (unlike the US however, we should wait till the technology is through its teething problems before requiring its use).
I don't know, there must be quite a lot of wives out there don't vacuum or iron
Owain
And longer than most extension leads would need to be, even as a subterfuge to get round Part P
Owain
Bright idea that no-one's ever thought of before (not): how about a hefty resistor concealed in a spare drive bay to fool the PSU into supplying enough current.
Owain
You can reduce the risk by using a short(ish) thin flex on the tool, and a heavy gauge extension lead.
Given time it would probably open the fuse... ;-)
Was it a double isolated tool? (i.e. 2 core flex). If so then there is no reason why the RCD would trip since it looks for an imbalance between feed and return, not an over currentfault.
Why? A circuit breaker in the same circumstances may behave in the same way. When the fault current is not high enough to reach the instantaneous part of its trip response (i.e. the solenoid operated bit), it behaves as a thermal trip device (as does a fuse).
Na, you need a more powerful trimmer so it can cut through the lead cleanly ;-)
On Mon, 01 Aug 2005 00:16:48 +0100,it is alleged that spake thusly in uk.d-i-y:
I had this issue with a PC (desktop) a few weeks ago. What I figured had happened was as mentioned elsewhere, it had come partly out and had sideways force applied. However, this hadn't affected the female connector, but the chassis male plug, which had its earth pin loosened and pushed back by maybe 1.5 to 2 mm. Enough to fail to make contact before the live/neutral. I put it down to poor design, a PCB mount socket used as chassis mount with the earth tail inside soldered/heatshrinked to the pcb pin.
50m x 0.75mm² is 3.1 ohms which is 77A, so it can't have been a short circuit as that would have blown the fuse within 10 seconds (possibly less -- I don't have the curves for BS1362 fuses). The sparking would also imply it wasn't a dead short, as that would produce no continuous sparking.
As I said before (probably in the previous thread), extension cords are probably one of the most serious sources of danger, and that's from several perspectives. It's not just a question of making them "idiot proof" -- most people with no electrical engineering or similar background really have no idea what the safety issues with them are, and many of the issues can hardly be said to be intuitive in any case.
In your case, you should really be using a much thicker extension cord for the bulk of that cable run. A rough guideline for 13A extension cord length is:
1.25mm² cable, 12m max 1.5mm² cable, 15m max 2.5mm² cable, 25m max.By reducing the fuse and max current, you could proportinally increase the length, so a 2.5mm² 50m cable with a 5A fuse would be within this. (Note however that you won't get 2.5mm² flex into the cord grips of most 13A plugs or line sockets.)
Something else that I've done is replaced my hedge trimmer cable with 3-core earthed. The earth is not connected at the hedge timmer end (like all garden tools, it's double insulated), but it does make it much more likely the RCD will trip in the type of fault you had.
However, again as I said before, electrical installations would be better designed to remove the requirement for extension cords at all. Shortly before Part P came in, as part of replacing my Consumer Unit, I included provision of outside sockets such that no part of the garden is more than 15m from a socket. They are on a dedicated TT-system circuit, and RCD protected at 10mA.
On 01 Aug 2005 13:19:04 GMT,it is alleged that snipped-for-privacy@cucumber.demon.co.uk (Andrew Gabriel) spake thusly in uk.d-i-y:
[snip]Indeed, definitely not a dead short, it was a case of the hedgetrimmer managing to slice through the neutral, not quite through the live, and thus the blade was live with the (badly burned) neutral touching it each time it was moved.
I discovered all this later, I somehow didn't have the urge to closely inspect it while live :-)
[snip]
Excellent piece of lateral thinking, I may just do this (although current house has a small enough garden that a 20m cord would be sufficient, so I will be able to use 1.5mm 3 core).
On Mon, 01 Aug 2005 13:08:44 +0100,it is alleged that Owain spake thusly in uk.d-i-y:
I wonder if IBM still have a few hundred thousand of those kicking around?
They finally found a PSU that would continue to operate at the appropriate draw. Other friends producing a more recent design dumped the PSU idea altogether and use a standard (external) adaptor giving 5v DC output for their new desktop computer.
Not in my book. He's just a cleverer commie than most. Dress up legalised extortion in a frilly dress and call it a major benefit for everyone.
These figures are for 240V, would be *worse* if 110V (building site style) was used in the interests of 'safety'?
Owain
Probably, now I wonder what their spares department would charge ;-)
Owain
Ah. You've sobered up somewhat?
Seek treatment for your addiction.
protected
appliance...
So you want people to haul out their appliances just to isolate them now....!
So you want people to have to haul out two or more appliances if one needs to be (re)moved ?!....
Err?!.....
badly
But that wasn't the issue, no one has suggested AFAIR that pre fitted plugs have been a bad thing.
someone
That's a design issue that could be cured in split type plugs though, the real reason moulded on plugs are used is cost.
,
protected
But we are talking about dedicated appliance circuits here, so where would the problem be?
No, have you never used a FCU to supply a flex to CU wall plate?
For all your talk about having things just so, you seem to be governed by cost rather than neat and accessible installations - as you say, whatever floats your boat.
,
workshop use
there.
using
You really don't understand this do you, the radial would not be rated at anymore than the 16 amps people keep telling me that all appliance flex's have to be rated for now - OTOH, if the BS1363 plug fuse has been bridged by some idiot.....
Anyone can, any screw of the same dia' of a BS1363 type plug fuse will do. :~(
It is if you consider the above...
carrying
Who says, seeing that one can buy it off the real in the DIY sheds.
The lamp or what ever might well come with only two meters of flex, but who knows if it won't be replaced with a longer length of the same section.
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