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› Connecting Earth wire(s) to metal back box
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Connecting Earth wire(s) to metal back box (Read 23509 times)
Lectrician
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Re: Connecting Earth wire(s) to metal back box
Reply #17 -
Mar 9
th
, 2005, 2:51pm
because we are talking very small figures here - less than an ohm.
If water was such a bad conductor, we would't have all these faults due to damp etc, and we could fit any IP rating outdoors
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Re: Connecting Earth wire(s) to metal back box
Reply #18 -
Mar 9
th
, 2005, 9:54pm
Less than an ohm??
hmmmmm
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Lectrician
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Re: Connecting Earth wire(s) to metal back box
Reply #19 -
Mar 10
th
, 2005, 7:39am
A socket circuit in a standard house - max Zs 1.2, usually half that!
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Re: Connecting Earth wire(s) to metal back box
Reply #20 -
Mar 10
th
, 2005, 11:31am
Nah I meant the water, water has a high resistance
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Re: Connecting Earth wire(s) to metal back box
Reply #21 -
Mar 12
th
, 2005, 10:59pm
water has a high resistivity compared to metals and the resistance of water in a 1m long domestic pipe is therefore generally high enough to be safe even with addatives in the water.
with your wet wall its not just a straight line down the wall its a huge triangle of wall from your socket to the ground (plus some effects from bits of the wall outside the triangle)
wires cables and pipes have a much larger length than any other dimension this means we can reasonablly approximate them as a wire with a perfect contat to both ends that covers the entire end.
with other shapes of objects the calculation gets much harder.
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Re: Connecting Earth wire(s) to metal back box
Reply #22 -
Mar 13
th
, 2005, 12:00am
Yikes, where you been PW!
oh yea, so in short you're thinking exactly what I'm thinking
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th
, 2005, 12:01am by LSpark
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Lectrician
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Re: Connecting Earth wire(s) to metal back box
Reply #23 -
Mar 14
th
, 2005, 7:26am
I thought he was saying you CANT compare it to the research done with pipes ???
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Re: Connecting Earth wire(s) to metal back box
Reply #24 -
Mar 14
th
, 2005, 10:29am
lol, dunno.. don't care
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th
, 2005, 10:31am by LSpark
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