Hi everyone so I finished working on my project which basically lets me control a relay through a website. I wired up all my components and mounted them in an electric box. I have maybe like an hour worth of electronics knowledge so I got help from my uncle. I've tested the device with a lamp and everything seemed to work fine. It's supposed to control an electric radiator but since I'm using a cheapo "40A" SSR from Aliexpress with no heatsink I don't think it would be a good idea to actually connect one. And I'm also not sure what the wires I'm using would be rate for. Basically I just want to hear a second opinion on how safe my creation is, if there are any glaring safety concerns etc. The only thing I can see being wrong besides the cheap components is that there is no physical barrier between the components like the relay and the charger that's used to power the ESP.
I'm including the diagram and a couple photos. The photos aren't the best because of the mess of wires all over the place but hopefully you can still see what's going on.
Nothing wrong with using cheap components. Even using salvaged components is acceptable for a personal project.
Your SSR does already have a heat sink. That is the aluminum plate on the bottom of the thing. If it gets too hot to hold, then you need to add more heatsink attached to the base plate, using a thin layer of heatsink compound between the two.
I will not make any comment on the safety of your project because it is your responsibility.
I will note your mains wiring is running close to all the other components and wiring. This is bad design and any noise generated externally will come in through those wires and be coupled to your sensor wiring.
Paul
How lucky do you feel ?
Do you trust the switched mode power supply not to connect mains to the (not earthed?) external metal work ?
srnet:
How lucky do you feel ?Do you trust the switched mode power supply not to connect mains to the (not earthed?) external metal work ?
Hi thanks for the input. I don't feel too lucky which is why I'm scared of working with mains voltage, which is probably a good thing, and haven't tested this with a higher load. If by external metal work you mean the box that everything is mounted inside then there shouldn't be a problem because it's plastic. Unless I misunderstood what you meant.
This is not safe. Especially hooked up to a radiator. SSRs most often fail closed. This is a huge problem controlling a heater. I think you might be better with a normally open magnetic contactor.
What current is the radiator?
akalion213:
If by external metal work you mean the box that everything is mounted inside then there shouldn't be a problem because it's plastic.
I would suggest that your 'hour worth of electronics knowledge' is no where close to enough experience to build a project like this in a safe manner, I would also recommend you dont use the project, bin it is the best option.
These forums are not an appropriate place for constructors with only an hour of experience to be told how to safely build mains powered equipment.
What is the purpose of the opto isolator ?
Hi,
Welcome to the forum.
Ops schematic;
The logic behind the button operation is a bit worrysome, but safe.
What part of the world do you live, if the UK them there will be a fuse in the mains plug, but if not you will be better off putting a fuse in the mains lead where it enters the box.
An indicator light on the mains side would also be good.
Tom.... 
PS. Nice to see you used boot lace terminations on mains wiring....
As beginner's jobs go that's not bad, but I agree with the comments about safety.
Unless I missed it no one has picked up that you don't have an earth on the output mains socket, in the UK that would not be acceptable, is is acceptable in your country? I can't imagine that it is.
The cable you have used looks like it's probably good for mayby 5A, which at 230V is 1150W, what is the power rating of the proposed heater?
If you learnt how to do this from your uncle I would think he's the best person to advise you as he can supervise you directly, we can't.
PerryBebbington:
As beginner's jobs go that's not bad, but I agree with the comments about safety.Unless I missed it no one has picked up that you don't have an earth on the output mains socket, in the UK that would not be acceptable, is is acceptable in your country? I can't imagine that it is.
The cable you have used looks like it's probably good for mayby 5A, which at 230V is 1150W, what is the power rating of the proposed heater?
If you learnt how to do this from your uncle I would think he's the best person to advise you as he can supervise you directly, we can't.
Yes my sockets don't have earth as I live in an old building. I've read a bit about this yesterday and from what I understand for most appliances it is not needed as they are double insulated. This is just a school project so I'm not intending to use it. Also the plug says it's rated for 16A but idk.
srnet:
I would suggest that your 'hour worth of electronics knowledge' is no where close to enough experience to build a project like this in a safe manner, I would also recommend you dont use the project, bin it is the best option.These forums are not an appropriate place for constructors with only an hour of experience to be told how to safely build mains powered equipment.
Hi, yes I'm aware that I'm too inexperienced to work with this stuff myself which is why I asked my uncle who is to check the project. I was not intending on using it myself as it's just a proof of concept for my assignment. Could you please explain what is wrong with the container? This post was mainly to just double check if I made some stupid mistake when connecting everything.
TomGeorge:
Hi,
Welcome to the forum.Ops schematic;
The logic behind the button operation is a bit worrysome, but safe.
What part of the world do you live, if the UK them there will be a fuse in the mains plug, but if not you will be better off putting a fuse in the mains lead where it enters the box.An indicator light on the mains side would also be good.
Tom....
PS. Nice to see you used boot lace terminations on mains wiring....
Hi Tom thanks for the reply. Could you explain what's worrysome about the button operation?
akalion213:
Hi Tom thanks for the reply. Could you explain what's worrysome about the button operation?
I can see you are using analog level sensing for your buttons, but you have enough digital inputs spare to connect the four buttons too.
I would put a 0.1uF capacitor between gnd and A0 pin, to help minimise switch noise.
Tom....
Qdeathstar:
This is not safe. Especially hooked up to a radiator. SSRs most often fail closed. This is a huge problem controlling a heater. I think you might be better with a normally open magnetic contactor.
So it's not safe because of the SSR, but would be fine with a magnetic relay?
Yes my sockets don't have earth as I live in an old building. I've read a bit about this yesterday and from what I understand for most appliances it is not needed as they are double insulated.
That is scary! Seriously, if the wiring is old enough to not have earths on the sockets then it is not safe. Is the property rented or owned? I would think the electrical system needs replacing. It does not matter that some or other appliance doesn't need an earth, the earth should be there for appliances that do, and not having earths to sockets is a sure indicator that the wiring is old and unsafe. You've not said which country you are in but in the UK that would not be considered safe and the building would need re-wiring.
PerryBebbington:
That is scary! Seriously, if the wiring is old enough to not have earths on the sockets then it is not safe. Is the property rented or owned? I would think the electrical system needs replacing. It does not matter that some or other appliance doesn't need an earth, the earth should be there for appliances that do, and not having earths to sockets is a sure indicator that the wiring is old and unsafe. You've not said which country you are in but in the UK that would not be considered safe and the building would need re-wiring.
It is very common in the US for any house built prior to 1960 to not be grounded. Also, many many appliances nowadays are two prong without a ground. Using ungrounded outlets is only unsafe if the appliances you are using has a ground pin... otherwise, roll on...
akalion213:
So it's not safe because of the SSR, but would be fine with a magnetic relay?
Safer. But the best option would be some sort of thermal fuse to blow on its own outside of the control system. It’s possible the radiator already has it though.
It is very common in the US for any house built prior to 1960 to not be grounded.
I'm horrified! That was 60 years ago, plenty of time to upgrade to modern standards. I do realise the US uses 120V, so I guess it's not as dangerous.
PerryBebbington:
I'm horrified! That was 60 years ago, plenty of time to upgrade to modern standards. I do realise the US uses 120V, so I guess it's not as dangerous.
There is no need, because, as i said, a lot of stuff you plug in isn’t grounded anyway..,,