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can think of ways of doing this on a pcb, but not on mains supply, Im wondering if any of the peeps that rip diy switches can think of an easy solution using off the shelf bits, ideally the gate needs to stay open when the 9v inputs stops(might only last 5 secs) ...so some kind of reset button will be needed ..but that's a ways down the line

looked at a few smoke alarm/'auto door open'/circuit breaker combos for office buildings, the bits were expensive and not really suitable ...but found this:




£29 Belkin Conserve Energy Saving 8-Outlet Surge Protector with Wireless Remote Switch - Surge suppressor - 8 output connector(s)
£10 smoke alarm
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hard to know for sure without seeing the inside of the 'remote switch' , but Im thinking when the switch is set to the 0 position, it completes the circuit and sends a wireless message to the 'power strip' to cut the power to the 6 sockets, the small circuit inside the switch has to be basic, shouldn't be difficult to set the 'remote switch' to '0 position' permanently by soldering a contact between the 2 points ..and using the 2 contacts on the smoke alarm bell as a means to close the circuit, dunno maybe remove the bell altogether, and put the 'always off' switch in its place

the bit I cant get my head around fully without seeing the switch circuit ...the 'switch' would need to take its power only from the smoke alarm hmmn ..maybe connect the bell contacts of the smoke alarm to the battery socket contacts in the remote switch ..with the switch contacts perm connected iow perm set to 'turn off' position

1. smoke alarm goes off, causing current to be passed across its bell contacts
2. current passes to switch battery contacts and 'power off' signal is sent to the strip

alternatively leave the switch as it is ...and solder the smoke alarm bell contacts directly to the component in the switch that sends the wireless signal to the strip, take some volt/amp readings from smoke alarm, and compare to volt/amp readings in the switch ..shouldn't be too hard to adjust with a small pcb to make them match

could just hardwire a relay from the smoke alarm, wouldn't wanna rely on a remote switch for this sort of application. have it so if the smoke alarm goes off the relay de-energises to cut the power, this way you have a built in failsafe, so if power is cut to the smoke alarm (melted cable etc) then the power will also be cut to the relay and the power to the whole grow will be cut off

not sure what the first post is in relation to?

looks like a smoke detector shuts off the power in case of fire/smoke

yeah the second post, not sure what's trying to be achieved in the first post though?

first post:
there is another kind 'power strip' I found before the belkin ...one socket is nominated as the switch, so whatever 240v device is plugged in ..if the device turns off or loses power then the strip cuts the power to all the other sockets ..I started thinking about using the current from the smoke alarm bell to somehow 'turn off a 240v device' plugged into the nominated switch socket ..effectively cutting the power

what you got in mind scribs for the relay, do you mean the 'off relay switch' inside the belkin strip ..just wire the smoke alarm in directly? ..or something external and homemade

ps
haven't given up on the remote switch, less wiring, and you will prob want the alarm and the sockets in 2 diff places ..also for peeps that don't know what they are doing ..it might be a bit safer

¿Couldn't you just get a normal electric smoke detector and where it normally connects to the piezo squealer alarm, disconnect that and instead connect it to a relay that when activated cuts power to your strip?

you should be able to get a smoke alarm with built in relay outputs, just use the relay outputs to switch a contactor that shuts off power to your grow. have a look at mains powered smoke alarms rather than battery powered ones. if you can't find one with built in relay outputs, then you could do as you suggest with using contacts that operate the alarm bell to also operate a contactor and knock out the grow, but again, look at mains powered smoke alarms, as you'll want the contactor to always be on, unless the alarm goes off or something happens to the detector at which point the contactor will switch off, ie failsafe, with the relay/contactor always on a battery powered detector will obviously need its battery replacing constantly, hence a mains powered detector. mains powered detectors will generally have more features such as relay out's as they're more often used for larger systems

isnt that what I'v got in my diagram?

that sounds like a plan

the remote switch is just that, so yeah your first diagram is fine, although i wouldn't bother with the fancy power strip, as you're switching HID's you'll need to switch a contactor (even though you may already have a contactor, as you are breaking power from the source, the switch will still be taking the load of the lights) so just use the remote switch to cut power to the coil of your contactor (not your lighting contactor, but a second one through which the entire grow is supplied), in the event of a fire/detector fault. although hardwired is always more reliable, but as you say, not always practicable

didn't consider that ..bit more thinking to be done ..a hardwire is looking more attractive now ..any ideas for turning off the 'entire grow' contactor using the relay outputs from the smoke alarm as you suggest?

Opps...Wrong reply in the wrong topic...Sorry.

not sure if this is what you mean scraglor? ..my knowledge of big electrics is a bit hazy, smt is bit more my thing ...ano its a bit luxurious using just one socket of the belkin but it keeps it simple and safe, I'm asuming the wirless technology in the switch is similar to a tv remote and will be fairly reliable esp. powered from the mains, I think they have a smaller version of the belkin with fewer sockets . I'v had a look at a few mains s.detectors with relay outputs + battery backup, tripping the belkin remote switch if the detector 'fails' might be a bit more complicated but not impossible, but do you really want to cut the power to the grow because the smoke detector has a fault? ... maybe a weekly test of the smoke alarm might be easier ...dunno tho

off to work now, i'm a bit confused, is the remote switch inside the belkin or part of the smoke alarm? should be able to just get a simple switch operated by the smoke alarm which operates the contactor, kind of like using the remote switch instead of a timer like your idea. although i was thinking more of a home made set up, with just an enclosure with a contator with power running through it with the remote switch located inside, the power then feeding a socket/s inside your grow room, wouldn't even necessarily have to be in the grow room (in fact better for it to not to be in the grow room) as for the smoke alarm cutting power under failure. it may become a nuisance if the smoke alarm gets a fault, but it depends why it's developed a fault, if it's because the wires melted before it's detected a fire then you want it to cut power, if your main feed contactor is outside the grow room you can also connect an alarm, beacon, whatever to say the contactors been tripped, hopefully not because of a fire, and if it is just a fault with the smoke alarm you can easily have a manual overide switch.

all a bit ott for a small setup though , i'm happy with just an rcd feeding my grow, an automatic fire extinguisher is on my wishlist though

every mains powered BS smoke alarm has an interconnect wire to trigger other alarms in the same property when one alarms. you take a mains powered smokey, attach a voltmeter to the interconnect wire, and earth, trigger the alarm, check what voltage appears on the interconnect, get a relay with this voltage required for its coil, and activate the coil from this wire. connect anything you want, i.e. lighting contactor, to this relay. if you find the interconnect is normally live, dead on alarm, use the nc contacts instead of the no contacts on your relay.

not sure if i explained that too clearly, half asleep at the time. when you get your mains powered smokey, make sure its interconnectable. wire it up on a plug and lead, and test it like this.

there will be live and neutral connectors, obviously the supply, you'll need a 9V battery in it, to stop it cheeping at you, there may be an earth connection, not always, but there will be another terminal for the interconnect wire. attach a wire to this, stick it into a connector block, along with the red lead from a voltmeter, attach the black voltmeter lead to neutral. if you attach it to earth, it may cause your rcd in the consumer unit to trip.

anyway, when you trigger the smokey, (with smoke, the test button on it may not fire the interconnect), check the voltage present on the interconnect. i expect its 240v, but it could be extra-low voltage, and still comply with the regs as its insulated to mains voltage capacity.

either, the interconnect will be normally dead, going live on alarm, or the other way about. it doesn't really matter, because you can use this to either pull in/drop out an external relay. (coil rated voltage same as the interconnect voltage). as long as this relay has both normally open and normally closed contacts, or even changeover contacts, you can use it. this relay should really be small, just to pull in another contactor or relay, as you dont know how much current the smokey output for the interconnect can source or sink. you could get into soldering and using a darlington driver chip to provide more current, but thats just more hassle than an extra relay. i think this should do the job, it looks like a system to shut down the mains supply to the grow if the smokey activates, a good idea that some grow shop/company really should have came up with by now.

it might be an idea to check what happens to the interconnect voltage when the smokey cheeps in a low or dead battery charge situation. it may well pulse, to force the other interconnected alarms to cheep too, although i suppose that could cause confusion over which battery is dead. but you can see that if it does pulse the interconnect, this would really screw you up, as your mains relay would activate for a split second every time the smokey cheeps. that would cause your supply to cut out momentarily every cheep, a quick way to knacker HIDs.

if you do try this, can you post what happens, and also the make/model no. of the smokey used, it could be a good cheap safety step, well worth pinning for everyone.

or the other way about. it doesn't really matter, because you can use this to either pull in/drop out an external relay

well it does matter really, if it goes live on alarm, you've got no failsafe, it should go dead on alarm, so if there's a fault, or the power gets cut to the detector for whatever reason, it'll still trip your grow

the 'belkin remote control/switch' in the middle of the diagram will be hardwired to the smoke alarm, but not the belkin strip itself, ano it seems over the top ..but Iv been thinking about this since the 'almost burnt my house down' thread and then the 'small hps fire' thread the other day reminded me I should probably do something, Im more afraid of fire than being busted ..what with endangering the neighbors and voiding home insurance policies etc ..its probably not rational but I hate going out when its on ...

belkin product page:
ht tp://www.belkin.com/conserve/

@mokum ..thanks for the detailed reply, that confirms a few things and gives me a few more things to think about, yeah Im amazed you can't cheaply buy something like this off the shelf considering the market
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just to confirm guys as Im a bit confused
looking at my last pic, the extension socket on the contactor(see 'grow supply') ...do I then plug a second diy contactor into that ..this one with a timer and then plug my ballast into 'its' extension socket,
or
will it be ok to use just one diy contactor(like the pic) ..except use a timer where it plugs into the belkin
also(looking at the pic)
could I use the spare 5 sockets on the belkin strip for the rest of the grows electrical items, as all 6 sockets will trip when the smokey goes off

thanks

not on a pc at the mo, but when i get a chance i'll knock up a quick drawing of how i personally would do it, or i'm sure if mokum is about he could go through it step by step

yes, i was thinking about the functionality of the circuit, as long as all the 240v loads, i.e. smokey, and whatever is being switched by the relay, are on the same circuit, a power supply failure would shut off everything, thereby failing to safety.

i was meaning that on a relay with both NO and NC contacts, the circuit would still function, as intended, you just use the other relay contacts to switch your load. rather than the relay coil being normally energised, it could be normally de-energised, going live on alarm.

but yes, you are right, if the smokey output goes live on alarm, in the case of a relay coil failing,then it fails unsafely. but, thinking about it, i suppose the same could be said about the interconnect wire between the smoke detectors, so it should be unlikely to go live on alarm, not in something as safety critical as a smoke detection device.

it all comes down to checking the voltages present on the interconnect wire in a test set up, before installing it. the best outcome is normally live, going dead on alarm, dropping out the relay coil and de-energising the load. probably the worst outcome is some kind of pulsed output, triggering the other smoke detectors, or in this case the relay, intermittently. i have never had to check the voltages on the interconnect, as its just a switchwire, and obviously all smoke detectors are disconnected before testing an installation, their electronics dont like megger tests.

i wish i had a mains smokey here, i'd check it on a plug lead myself, its probably 240V, and as you say, normally live, but i think its still worth testing, as different makes may work differently.