Hi guys

What is the safest way to detect main? I need to be able to detect if main is available, what is the safest way to do this? Thanks guys!

 

Mini neon bulb inside one end of a tube with a photodetector at the other end.

 

Buy an electrician's voltage detector pen for $10 at Home Depot.
Get a neon panel-mount indicator lamp built for 240 volts and learn to tell if its at full brightness or half brightness.
Wait...you're not in 'Murica.
I don't even know if you have 120/240V in NZ.
Anyway, both methods will work for 240VAC.

Whole lot of guessing going on with no application specified.

 

I am guessing this has to do with the power supply? Did the current power supply not have a power good output?
Safest - Just get the smallest transformer you can find that outputs 5 volts. You can connect that directly to your logic. No need to scale anything after.

 

What is the safest way to detect main? (120/240) I need to be able to detect if main is available, what is the safest way to do this? Thanks guys!

I thought NZ had the same as Australia which is a 240v single phase and neutral I believe?
Either use @#12 method or use a DMM (meter).
Max.

 

Buy an electrician's voltage detector pen for $10 at Home Depot.

I like this non-intrusive detection, now I need to find out how a voltage detector pen works. Thanks for the info.

I don't even know if you have 120/240V in NZ.

We only have 240V, but I added 120V to make it a more general question.

Whole lot of guessing going on with no application specified.

The info need to be readable by a MCU, I am detecting main fail to sound alarm.

I am guessing this has to do with the power supply? Did the current power supply not have a power good output?
Safest - Just get the smallest transformer you can find that outputs 5 volts. You can connect that directly to your logic. No need to scale anything after.

Yes, this is part of my power supply. No the current supply does not have a power good output. It only have two outputs, one for charging a battery, one for a load. When main is available, it charges the battery and power the load. When main is gone, it powers the load through the battery, and it also do low voltage cutoff.

I thought NZ had the same as Australia which is a 240v single phase and neutral I believe?
Max.

You are absolutely correct.

 

Screwdriver/Neon detector, non-invasive.
Measures leakage to earth.
http://elite-supplies.com/product/d...0v-mains-power-electricians-65mm-neon-tester/
Max.