I need to change an electrical switch for a heater in a rural house. I know I am not a professional but it is very urgent and a qualified technician will come over tomorrow to check it.
I've a Clipsal 20A switch on hand but the info on Clipsal's website does not contain details.
I would like to know the followings,
1. The meaning of COMMON, because the old switch has black lines connecting to the COMMON holes
2. The meaning of LOAD
3. There are two colours of wires, RED & BLACK. Which one is LIVE? And which one is NEUTRAL? Can I tell from point 1?
In fact, the old switch has 4 holes, too:
1. Hole 1 connects to a red line
2. Hole 2 connects to a black line
3. Hole 3 connects to a red line and to the LOAD (which is actually the neon light)
4. Hole 4 connects to a black line and to the LOAD, too.
I believe it is because 雙相 is used now, so there are two pairs of red and black lines.
I don't suggest you doing by yourself. It is very dangerous for high current connection. It may damage by heater, your other electrical devices and may hurt yourself.
I do have experience to change switch like that one you mentioned. If it is on off switch it should not be double phase power.
For me I have voltmeter, and know the procedure to turn off main switch and measure all wire has electricity by the voltmeter before use hands to touch.
You case is not complicated but if you never do it before, don't do it yourself.
The worst thing is if you change the switch with reverse order, you still can turn on the heater but if you think it is off already, actually there still has current going through the heater just wait for something to short circuit, then i will hurt you or your family.
1. COMMON means NEUTRAL, in general , it is "black" wire
2. LOAD means the current (A) of the equipement used. In this case, it means the current of the water heater.
3. Normally, RED is for LIVE and BLACK is for NEUTRAL
Your water heater may be the single phase type. 2 wires ( RED and BLACK wire, it may be hole 1 and 2)come from power supply and the other 2 wire ( another RED and BLACK wire it may be hole 3 and 4) connect to the water heater.
Please be reminded that any electrical connection work shall only be done by a registration of electrical work in HK
Thank you very much Cats. Now I think I completely understand the "standard", though I did not do the wiring myself at all.
I also found the answer from House18.com. And I learned that that 20A is called "燈曲" which cuts off both live and neutral wires at the same time (supposingly more safe).
I believe I am so aware of the safety problem. That's why I asked for help here. I was trying to estimate the risk by doing so.
In fact, that place is a separate little house and the heater is not for bathing.
If you accidentally swap the two pairs of red and black line, the neon light will keep turning on. It is logical because it is being connected to the live circuit.
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