I've never put together an AC circuit before and I want to make sure its safe. Essentially what I'm doing is interrupting the line that connects the mains to a DC power supply; and adding a reset themostat and a hall effect sensor. I want to add junction boxes to make sure everything is safe. However, I have no clue which ones to pick, what the IP ratings mean etc. If it helps its going to be in an indoors installation, the mains will be 220 and the heat in the room can potentially reach 75 degrees Celsius
here is a picture i drew up quickly in paint of what i want to do.
the heat in the room can potentially reach 75 degrees Celsius
Wow that is hot. Most commercial electronic devices are only specified to work up to 70C. Also most equipment is only specified to between 50 and 60C.
I assume the thermostat is just a mechanical cut out so no problems here
Anyway I have concerns about the Hall effect sensor. What is this connected to after it goes to the mains and how it it isolated? That is the potentially dangerous part.
That's OK as it is an inductively coupled circuit.
However I wonder if it will be sensitive enough for your needs. I am not sure what the output of the DC power supply is but remember that at a theoretical maximum efficiency a 1A 12V output is only going to register :-
1 * (12 / 240) = 50mA
even assuming a poor 50% efficiency the mains current draw will be 0.1A
Now I think you only get 50mV or so for a 57A current but I am not sure as the data sheet was hard to read.
Hmm... I didn't actually take a look at the hall effect sensor. I just picked one to show the type of part we are using. Another person is interfacing the hall effect sensor.
In terms of the safety of the AC circuit. If I make sure my wires are capable of handling the current and I have junction boxes to enclose areas where open wires exist, am I reasonably safe?
Side note: Btw, Grumpy Mike: Thx a lot for all the help over the years. Ive been working on a LED as light sensor solution and just came across your research on reverse biasing them. I'm now testing them in a photovoltaic mode to complement your studies on its photo conductive properties.
The two wires in the circuit are live and neutral right?
yes but from a safety point of view these must be treated as the same. That is don't do anything that relies on there being little voltage between neutral and earth.
what do I do with the ground coming out of the mains?
Don't temp me
Just take the earth where ever it would have gone normally. Also if this is being put in a metal box then connect that also to earth. However there is no need to do anything special. The purpose of an earth is to act as protection if the mains gets shorted to an exposed metal that could be touched. It is supposed to blow the fuse in that situation.
