This blog will hopefully document my experience of building an extension on the side of my house. It's purpose is probably two fold - firstly to allow me to keep a diary of events should the whole thing go pear shaped, and secondly so my friends and family can keep up to date with progress, without me having to mail them.
I forgot to mention this in my previous post. Can any of my clever readers enlighten me as to how a mains electric drill with a metal gearbox casing can get away with a plastic earth pin on it's plug ?
posted by shadaswell @ 4:25 pm
4 comments
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4 Comments:
Unless I am totally in error (!) plastic E pin/no earth means "double insulated" which I hope means nothing inside can touch the casing in times of breakdown. Now someone tell me I am up the proverbial creek. The sign on the case should be two squares inside each other. Signed "clever clogs" but subject to correction. Meantime - we approve heartily Jan's emergency tool kit. Very forward looking. J & B (REssex).
And the casing is probably plastic anyway! Yup, J(?) has it exactly right, and I can "Bore at England International Level" on the subject of DI; it is a big issue in ASTR.
PS you could have asked Jan about it, after all she's still a member of that fine body of folks, the "Institution of......whatever-it-is-that-we-call-ourselves-these-days" (sorry, that was an in-joke for me & Jan)
Thanks J&B - you are right, the concentric squares are there on the casing. However, I am not sure I understand the advantage of double insulation over provision of an earth. Surely a plastic pin on the plug isn't that much cheaper than a metal one ? Is it because some countries do not have an earth in their wiring schemes ?
Chris, the casing is at least part metal - I think the gearbox immediately behind the chuck. Jan says, what can the members of an Institution of All Trades possibly know and understand about the specifics of Electrical Engineering....
Oh dear, I sense a rathole, blog hijack coming on !
Cheers,
Steve.
As the production lot(i.e. non electrical.....) in the "Institution of Every Trade" would tell you, in a production line manufacturing environment you are always trying to shave fractions of a penny of the ex-works cost. Plastic is cheaper than metal, both the cost of the raw material and the cost of "manipulating" the raw material into the finished article, say an earth pin for a mains plug; two core cable is cheaper than three core. a penny saved on the ex-works cost of one unit is a pound saved on 100, £10 saved on 1000 etc etc (read the beginning of Arthur Haley's novel "Wheels").
Which is why you can buy a black and decker for 30 quid but the price of Skynet 5D has a very large number of noughts!!
Sounds like a good discussion for a couple of bottles after dinner! S will email Jan tomorrow.
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