Thermal Breakers in microgrows

[Flinders]

Hey guys

Just setting up a stealth PC box much like the famous "Nanomachine (split areas for growing and power plugs etc)."

Went down the electronics shop and bought a couple of those "always closed" thermo breakers as I'm paranoid about fire in the electrical compartment:

What would be the best way to rig this up? I have the back plate of an old PSU, connected to a chopped extension cord, which a double adapter then plugs into(for lights & fans). I was going to wire it between the back PSU plate and chopped extension cord.

From here I was going to run the "live" wire of the power/extension cable through it, and leave the earth/ground & neutral as are. Would this be the correct way to do it?

Be great if anyone can help me. Bit of an electronics nub, so like to check things out before trying.

Also, this is my first post. Looks like a fab community, cheers.

 

[ScrubNinja]

Hey man welcome to ic. What temp does it shut off at? I think what you have planned is right but I've never used one and have only a passing interest in electronics. I think with any kind of switch it should be the live wire going through the switch so my guess is you're correct.

Did you check this is for ac power and can handle the current needed etc?

 

[Flinders]

Hey man welcome to ic. What temp does it shut off at? I think what you have planned is right but I've never used one and have only a passing interest in electronics. I think with any kind of switch it should be the live wire going through the switch so my guess is you're correct.

Did you check this is for ac power and can handle the current needed etc?

Hey man

Specs are:

- Operating: +/- 5°C
- Reset: 10°C min. below opening temp.
- Contact Ratings: 10A 240VAC 10,000 Cycles
- Contact Resistance: 50 milliohm
- Connection: 1/4" (6.35mm)
- Quick connect tabs
- Diectric Strength: 1500VAC 1 minute
- Surface Contact Area: 50mm squared (16mm dia.)
- UL, CSA Approved

Opening Reclosing
Temperature Temperature (approx)
60°C 40°C

I think this looks about right for mains AC (Australia), but I'll be doing a lot of research. My biggest ??? is amperage from mains. Pretty much every power-plug and powerboards etc is rated at 10A, but I don't know if 10A is coming out of the wall socket or what. I might have to put something between mains and the switch.

Doing this blindly could ironically cause more of a fire risk lol. I might try and hunt down that Russian guy from the Nano thread... don't know if he still posts. He's the one I got the idea from. Something rated at 40ishC would be perfect for the growing compartment too. I hooked one up to a fan this arvo, put it on a thin sheet of metal and flicked a lighter underneath. Within a few seconds the fan stopped, so they look like a really handy device.

Oh by the way, hats off to you. I originally had a whole clumsy powerboard in the box, then saw your thread about doing things parallel and using a double adapter instead.

 

[ScrubNinja]

Oh by the way, hats off to you. I originally had a whole clumsy powerboard in the box, then saw your thread about doing things parallel and using a double adapter instead.

Haha cool! Yeah I don't get the whole powerboard in pc thing

Well all I can say is I think you're fine to go ahead in my opinion. All the timers and boards etc I've ever used are 10 amp and I did ask a sort-of electrician about it ages ago and he said a few CFLs is no problem for that at all. Found this too:

Australian 3-Pin Electrical Mains Plug

The domestic mains power supply in Australia is 240V AC, 50Hz. Standard 3-pin earthed power outlets are rated at 10Amps and are usually switched.

There's also an Aussie section of the forums here, and there's another forum altogether called ozstoners if you need more local electrical info. I may even copy you if it works!

Edit: one thing, wouldn't it be better to have one that switches off but doesn't come back on?

 

[Medical]

The 10A rating means that it can handle up to 10A. If you are running CFL's you will be no where near that. A 1000W HPS on 240 would not draw 10A.

As far as which wire to run through the disconnect, with 240 both lines are "Hot", one is hot and the other is the neutral during one phase and then they reverse roles for next phase and so on. So I would install a shut off on both wires. The reason being if one "pops" the other line will still have voltage at it but everything inside the box would appear to be dead, causing a shock hazard. Make sure to connect the ground wire(bare wire) to the case.

I just did a quick google of this, found an article that simplifies it a bit.

http://www.nojolt.com/basic-220-circuits.shtml

 

[Flinders]

The 10A rating means that it can handle up to 10A. If you are running CFL's you will be no where near that. A 1000W HPS on 240 would not draw 10A.

As far as which wire to run through the disconnect, with 240 both lines are "Hot", one is hot and the other is the neutral during one phase and then they reverse roles for next phase and so on. So I would install a shut off on both wires. The reason being if one "pops" the other line will still have voltage at it but everything inside the box would appear to be dead, causing a shock hazard. Make sure to connect the ground wire(bare wire) to the case.

I just did a quick google of this, found an article that simplifies it a bit.

http://www.nojolt.com/basic-220-circuits.shtml

Cheers for that, I think I understand but will have to do some reading on grounding.

I've knocked up a basic example of what my electrics will look like so you can see where I'm coming from:


Is this sort of what you were saying? (Both live & Neutral going through a seperate breaker). I'm confused with these 2 dangling ground wires. I was planning to just join them up, but you're saying attach them to the case?

Edit: one thing, wouldn't it be better to have one that switches off but doesn't come back on?

Possibly, but I'm undecided. Any fire is probably going to come from excess heat build up/wires getting too hot ('shorts' shouldn't really occur if I insulate properly).

With the hot summer approaching, the box can 'thermostat' itself. Even if it flicks on and off 100 times in a day, it'll never get much over 60C, and some continuity with lighting/fans will be maintained. If it just kills power for good, well there will be no light or ventilation until I get home.

It would suck to have some major electrical fault though, where power gets returned after it has just saved my arse.

 

[Medical]

Ok just reread and saw you are in Australia, thought you were in North America! Our 240 works differently than yours, not 100% but from my quick research you only need to install the disconect on the brown and join the ground and neutral.

Again I am familiar with North American wiring not Australian.

 

[Flinders]

Ok just reread and saw you are in Australia, thought you were in North America! Our 240 works differently than yours, not 100% but from my quick research you only need to install the disconect on the brown and join the ground and neutral.

Again I am familiar with North American wiring not Australian.

Thanks for sort of confirming that. I was beginning to think this was the case around these parts after a night of research. Well, I'll obviously find out for sure. It's a little hard to get info on such things here, as they've made it illegal to do any mains-related, DIY wiring... probably for good reason.

 

[Medical]

Thanks for sort of confirming that. I was beginning to think this was the case around these parts after a night of research. Well, I'll obviously find out for sure. It's a little hard to get info on such things here, as they've made it illegal to do any mains-related, DIY wiring... probably for good reason.

Well you are not doing any thing with the mains are you? You are just running a wire from your fuse panels to your grow correct? I think when they say mains they are refering to before your panel.

 

[Flinders]

Well you are not doing any thing with the mains are you? You are just running a wire from your fuse panels to your grow correct? I think when they say mains they are refering to before your panel.

Your definition of 'mains' sounds a bit more correct. Yeah, this will just be plugging in to a wall socket like any appliance.

My misuse of 'mains' aside, you have to get an electrician to do any wiring here relating to your house, or any light fixtures etc. I'm not allowed to put a new light switch in, or rig up some battenholders in parallel, even to a plug. I don't really know where I stand here, but growing weed isn't exactly legal anyway lol.

 

[ScrubNinja]

Article here if anyone is interested.

For example, this issue also involves anyone who wants to work on vintage radios – they are mains-powered aren’t they! Not only in Queensland, but now in most other states, you can’t legally work on your own vintage radios. Happy with that? And amateur operators? Sorry, you can’t touch a mains-powered transceiver.

In fact, we’re talking about anyone who wants to assemble or service mains-powered equipment, whether it is a DIY project described in SILICON CHIP, servicemen working on TVs, VCRs, microwave ovens, photocopiers and printers, PCs and their monitors, and so on.

 

[Flinders]

Article here if anyone is interested.

Interesting article.

I was trying to pm you about another (really nub) question, but can't find any pm option.

Anyway, you mentioned how to hook up batten holders in another thread. How are you supposed to attach the wires to the screw terminals? I was just going to make little hooks and attach them to the outside thread of the screw... then screw it in.

But... am I supposed to be shoving the wires in the holes or something and then screwing in?? Don't think this would be the case, but I've never really worked with battens before.

Sorry, I'll leave you alone after this.

 

[ScrubNinja]

Haha no worries at all man, ask away. I think you need 50 posts to send PMs. What I do with aussie batten fixtures is strip the wire, make sure the strands are twisted good, then bend it over sharply on itself near the tip. I have no idea if that's helpful, someone told me recently that's how to do it. Then you unscrew the screw a little bit, don't remove it > Stick the short exposed bit of wire into the hole and tighten the screw again, clamping down onto the bare wire with the tip of the screw.

With the way I did mine in my pc, you don't need to attach the ground wire like I did (apparently). Since then I've skipped the green wire. Makes for less wiring too.

Edit: if you're wiring in parallel, and need two wires in one hole, twist the two wires together, then bend (if you want), then insert in hole.

 

[Flinders]

Lights and thermal breaker all wired up! Did the lighter test again, and the lights flicked off... and I didn't even get electrocuted! Left enough cable to wire another in the grow compartment, but I'll have to find one much less than 60C.

I ended up connecting the Earth to the lights anyway. Yeah, you only really need to Earth lights (or anything) if they have a metal batten holder, fixture etc that could touch a wire.

Can finally get on with the sealing, painting and testing

Thanks so much for your help mate, and Medical for making me read more

 

[ScrubNinja]

Friggin awesome my man. Where did you get your breakers from...somewhere like dick smith or jaycar? How much?

 

[Flinders]

Yeah dude, Jaycar. http://www.jaycar.com.au/productView.asp?ID=ST3821&keywords=thermal&form=KEYWORD

 

[ScrubNinja]

Thanks man.

Cheap too. It gets no better than this.

 

[ScrubNinja]

Hey I thought I would post a pic of a light I bought today, came without a plug. It illustrates the wiring restrictions well.



Peace out