Evening all,
With the storms that hit Sydney, Newcastle and the rural areas around this week I have faced a new problem when our grid supply went off. How to know if its back on again!
Sounds obvious, just leave a light on. No. The problem is we have a 3 way change over switch, ON-OFF-ON. One of the ON positions is for the Grid supply, OFF is everything off and the other ON is for the generator.
Essentially when our power goes off we switch over to the Generator. This works great but does require me to go and inspect the supply meter to see if the display is âonâ and therefore we have grid power back on and I can then revert to it.
Question:
What would be the best (legal) way to detect if the Grid supply is back on?
I cant measure power flow through any of the regular domestic circuits because they will have power from the generator.
I did wonder about putting a clamp around the cable from the meter to the main house fuse but I suspect that would read Zero until the switch is switched and we start consuming grid power.
I also thought about a light sensor placed over the meterâs LCD display but I suspect that would likely be subject to false positives if the meter box gets opened.
At least powering the device should be easy because it can be fed from the house circuits.
Any other thoughts on how to capture the data / state?
I would be happy with an email notification or maybe even a WhatsApp message through their API. I know the latest Shelly software allows notification via both email or Webhooks.
Hi Jon.
I am not trying to br funny but do you have any street lights that you can see although that would not help during daylight hours.
I think to indicate you are going to have to connect something directly to the supply. I donât know about the legality of this. Might have to consult an electrician. There could be some sort of commercial device available, possibly non invasive. Donât know as I donât have a generator and usually just leave a light on.
That is correct. These are AC current devices, no current no output.
Cheers Bob
You will need to be careful about what you put in your meter box. There are rules and regs and I believe you are not allowed to install appliances/Power Points etc âinâ the meter box, so you would need to check with your local laws/regs on what can/cant be done.
That said, the simplest thing I could thing of would be to have a new âmains onlyâ power point installed somewhere (simples runs to keep costs down).
then connect to that power point some device that on power on, sends the email.
Of course this assumes your local network is up and your internet is up.
If you want to go a little more complex, you could have the device above to send a message local that could then display something. e.g. point to point wired/wireless link.
While I will leave the mains connections/detections to a real sparky, what you can do post that is really up to you.
The idle current is a few Watts. Not nothing, but not all that significant.
Your sparky would install it on the grid side of your changeover switch. Itâs then up to you what you hook it up to for the alerting side of things.
(Single-phase failures were more common than total outages when we lived in Sydney, and we found outselves blissfully unware of one in particular until we opened the fridge and the light failed to come on⌠Now we know if any one phase goes out).
Hi Jon
Google âmains power back indicatorâ. You will see 3 U-Tube videos. They all show a âRelianceâ audio device installation. Now I looked up Reliance and could find no mention of this so maybe not available any more.
The interesting thing is the mains present sensor. It is a wire coiled around the incoming wire (non contact) but I noticed it is left open at the end. That is not connected to anything. This in fact turns this into a CAPACITIVE probe as against an INDUCTIVE one with both ends connected. This should work without current flow after all the sensor on dedicated devices and multimeters work with only a voltage presence.
Have a look at these U-Tubes and you will see what I mean. This voltage will not have any grunt, by that I mean will have no current capability so will have to be applied to a high impedance input device like a simple OpAmp voltage follower for processing with whatever you want to do with it.
Might give you a non invasive connection system for some ideas.
Cheers Bob
Given that this would involve mains power, I would recommend consulting with a licensed electrician about possible solutions and for having the work done.
Guys,
Thought Id report back - I have found a solution to my problem, without having to re-invent the wheel!
As it turns out my solar system has a couple of hidden entities that it presents to HomeAssistant, one of which is âGrid ONâ or âGrid OFFâ.
Once I found this out, the rest is easy, just setup an automation in HomeAssistant to monitor for a change in entity state and thereafter send out a notification!
Before I found out the above, my physical solution was going to be a NC contactor connected on the private side of the the incomming grid breaker and then either a home made opto-isolated circuit connected to an ESP32 or a shelly pro. I figured this way would eliminate any potential issues with wrapping cables around a supply wire and would also eliminate the potential for any stray induced voltages and thus false notifications.
