ST-029 Smart Home Light Switch - How To Identify Live/Hot Wire, Neutral wire, Ground Wire

How to Identify the Wires from your Home Switch.

Usually your light switch would have the structure as below picture:
if the electrician who installed it followed the electricity regulation.


Live/Hot wire is with black or red color.
Neutral wire is with white color.
Ground wire is with green color. 
(ps. ST-029 doesn't require Ground wire, no metal surface, so it's safe and no need Ground wire. ) 
when you pull out the wall box, you would find that you can only see wires, but not able to see the wiring diagram.
Tip 1: from the switch 2 wires, one is the Live/Hot wire and one is the load wire, remember this would be easier for you to identify them.


Requirement: voltage detector or multimeter , basic electrician knowledge. ( note: if you are not familiar with electrician work, please contact professional help for safety! )


case 1: Wires are with correct colors
hat's to say, Live/Hot wire with black(or red) color, Neutral wire with white wire. 
then it would be easier, you only need to check which one is the Load wire.
usually Live/hot wire and load wire are with the same color. load wire would be connected to Live/Hot wire when switch on.
so to distinguish them, when power (from circuit breaker ) is on, Live/Hot wire is always with voltage. while load wire would only get voltage when the switch is on.
when switch is off, it's not with any power!
so that you can check which one is not with Power when switch off, that one is load wire.
then you can identify all the wires and connect them now.


case 2: if you can't identify from colors. 

1st, use voltage detector or multimeter to find out Live/Hot wire first. this is easy to identify. and combine this info with "Tip 1", you can know the Live and Load wires.

2nd. the difficulty is to distinguish ground wire and neutral wire
Remember this important "Tip 2", the voltage difference between Live/Hot wire -- Neutral wire is higher than Live/Hot wire -- Ground Wire.


for multimeter, Use the V with a wavy line to measure AC Voltage. ( abouve AC 600V/750V scale to be safe)


Now that 'live' wire has been identified, test voltage between the 'live' and the remaining two, one at a time. Whichever gives you higher reading is the 'Neutral' and the other 'Ground'.


if you don't have a multimeter, you can also make use of AC bulb. Connect Live and the remaining two, one at a time. Whichever gives you Brighter light is the 'Neutral' and the darker one is'Ground.

then you can identify Neutral and Ground now. so are the Live/Hot wire and Load wire. then connect them.



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