Earthing questions

jon · 2006-05-03T13:06:18+00:00

Having read quite a few articles on earthing (including the uk-diy faq), I am still a bit confused and was wondering if any kind soul could answer the following questions.It would be handy if you could explain in non-technical terms.The following scenarios all relate to a metal cased (conducting) table lamp connected to standard domestic mains by a standard 3-prong plug, where the live (or phase, or the red wire, or brown) has touched the lamp case. In all cases I will be standing on the carpet wearing shoes. Where there are no fuses in the scenario it is presumed the connections have been hard wired.What would happen to me if I touched the lamp casing?1) If there was no fuse at the consumer unit, or in the plug, and no earth connected to the plug,2) There was a 5A cartridge fuse at the CU, but no plug fuse, or earth connection.3) There was a plug fuse, but no CU fuse or earth connection.4) There were fuses at CU and plug but no earth connection.5) There was earth on the plug and at the consumer unit, fuse at CU, but not in plug.6) There was earth connected on the plug and at the consumer unit, fuse in plug, but not in CU.7) There was earth connected on the plug and at the consumer unit, fuse in plug, fuse in CU.8) Any other scenarios where a) I simultaneously touched a water pipe that wasn't earthed, or b) where it was.Many thanks Jon

May 03, 2006 30 Replies

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meow2222 20 years ago

If you dont let go of it, yes. Sjock mostly causes the person to pull away very fast, but if your hands are round the thing, youre history. Funny thing about electrocution is time slows down, when I've been bit I could tell you how many half cycles it was.

The leccy takes every available path. The lower R the path, the more the i down that path. This is the point: earth rods arent zero resistance, so during live to earth faults the house earth system rises up in voltage. Depending on installation design, it can rise to anything from 50v to 240v, and do so for anything from milliseconds to indefinitely.

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meow2222 20 years ago

If you commit murder with a table lamp, would it be an accessory to murder?

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PJ 20 years ago

You might get a light sentence - if the judge is a bit dim ;-)

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mheden 20 years ago

"You might get a light sentence - if the judge is a bit dim ;-) "

...and if you didn't, you might be entitled to lodge an appeal with the Ohm Secretary :-)

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Owain 20 years ago

It would be most illuminating, watt.

Owain

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jon 20 years ago

both of those jokes are shocking!

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Bob Eager 20 years ago

I despair at the current level of humour...but I'll wait a mho to see if it improves...

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mheden 20 years ago

"both of those jokes are shocking!"

Shocking? Watt are you saying?

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Dave Plowman (News) 20 years ago

I found them most illuminating.

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meow2222 20 years ago

I suppose at least it would be the murder wea-pun.

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John Rumm 20 years ago

Much will be dictated by the carpet and shoes. If they act as very good insulators you ought to be fine... just hope it is not a damp day! ;-)

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