Why do electricity and water “not mix”? e.g. “Don’t touch electrical equipment with wet hands”. Is the problem that water conducts electricity?
If there is not supposed to be electricity in bathrooms, and it has to be a pull-cord lightswitch, why can we use electric showers?
How does water affect electricity transmission? Exposed power lines and pylons get wet. Transformers and sub-stations have water on them when it rains. Why does this not create a problem?
yes, it’s becasue water conducts electricity. IIRC, pure water isn’t a very good conductor, but it becomes better with impurities.
Electric showers are specifically constructed to keep the water and elec separate - and they should always be installed by a pro electrician
It doesn’t cause a problem because there is no where for the elec to go - it’s the asme reason birds stand on wires without getting fried.
oh, and a quick disclaimer: IANAElectrician
Actually, household water and electricity mix better than you think. Not as well as copper and electriciy mix, though. Distilled water is a poor conductor, in fact it’s listed on dielectric constant tables:
Air 1.0
Balsa Wood 1.4
Fir (wood) 2.1
Carbon Tetrachoride 2.2
Vaseline 2.2
Paraffin Wax 2.25
Mohogany 2.4
Rubber 2.5
Paper 3.3
Glass 4.0-7.0
Bakelite 5.0
Mica 5.5
Formica 6.0
Porcelain 6.0
Celluloid 6.2
Ethyl Alcohol 28.0
Distilled Water 78.0
These numbers have no real significance by themselves because they are not units of measurement, but mathematical constants. However looking at them side by side allows you to see the relative strengths of one compared to another.
Common household water is chock full of minerals & impurities that significantly lower it’s electrical resistance. Contact resistance of dry skin is typically in the hundreds of Kohms. Damp skin can have contact resistance as low as a few kohms, which is low enough that you could draw 20-50 mA of current through your heart, if you are unlucky enough to grab hold of 120V with one hand and the tub faucet with the other.
Good point - I should perhaps have mentioned that I certainly don’t include tap water when I say ‘pure’ water… only distilled, filtered water counts as pure, IMO
Colour me curious! Call me old fashioned, or out-of-the-loop, but I have to ask:
What on earth is an electric shower?
Some new-fangled 'merkin method of execution? Or a plain old shower, where the shower-curtain is controlled by a micro-controller and stepping motors?
??? You’ve never come across an electric shower? Basically, it’s a shower where the water is heated in the shower (by electricity, surprisingly ) instead of pulling it from the hot water tank.
I think some models also have an electric pump to make it a pressure-shower
I’ve never heard of them either, but here they are. Looks like the “hot water on demand” idea that has entirely failed to go anywhere here in the states. I don’t see why the listed “key features” would make it worth while:
The thing even costs twice as much as a water heater!
Maybe if you had a big house and a small water heater, and were constantly having to resort to cold showers because the dishwasher & washing machine were using up all of the standing hot water supply.
They are quite common in the UK - I prefer them, certainly, because it’s much easier to set the temperature - and you only have to do it once! Also, it means you’re not paying to heat up water you never use (if you don’t have a shower) and in my house (which currently has a standard shower) the hot water runs out after about 2.5 showers…
Where do you live? In the US we certainly have electricity in bathrooms (and have had for many years, even before ground fault interrupters). No requirement for pull cords.
My one visit to the UK indicated the same thing there - electricity in the bathroom is not a problem.
in the UK, There is usually a requirement for switches in bathrooms to be safer than usual, which usually seems to entail a pull-cord switch, not sure why. presumably other switch-types are fine if they are sealed
The rules for electricity in bathrooms in the UK are:-
All light switches must have pull cords.
No mains sockets except for low current ones for electic shavers which must have an isolating transformer and have a low value fuse. They also have a different pin configuration to the normal mains socket.
All other electic devices ( such as heteated towl rails )must be supplied via a hard-wired fused spur.
And don’t forget that the mains voltage in the UK is 230 volts so we have to be that more careful.
Reason that the wiring regulations are so much stricter in bathrooms in the UK is that it is one location where the operator is likely to be at their most vulnerable to electric shock.
You are more likely to be wet, even if its just the hands, you may well have no footwear on and be wet, having just taken a shower or bath, your eyes may be soapy so you may not be very precise in locating operating switches.
Its not just that water is a good conductor, it isn’t particularly, but compared to dry hands which are much less good at conducting current, water increases contact area, and does lower the electrical resistance.
In addition to the consumer equipment, any exposed metalwork absolutely must be earthed, including drains, shower rails, piepwork, and the specification for the earthing network is very rigorous.
Water can affect high power distribution, but the design of the insulator supports precludes this, but those insulators do have to be kept clean, fog can cause problems with these insulator stacks if there are any microcracks in them, which is common enough.
) instead of pulling it from the hot water tank.