# Low power smoke detectors?



## Willowdale (Mar 19, 2007)

I learned this morning that electrical code requires smoke detectors hard wired into a dedicated circuit. It's exactly the kind of phantom load I *don't* want (the house is off grid and I don't have amps to waste).

Of course I know I can keep that circuit switched off and run them on battery mode only. Questions:

1. Do these hardwired detectors run down batteries faster than the ones that are intended for 24 hour battery use? 

2. Are there super efficient hardwired smoke detectors?

Thanks!


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## Gary in ohio (May 11, 2002)

Willowdale said:


> I learned this morning that electrical code requires smoke detectors hard wired into a dedicated circuit. It's exactly the kind of phantom load I *don't* want (the house is off grid and I don't have amps to waste).
> 
> Of course I know I can keep that circuit switched off and run them on battery mode only. Questions:
> 
> ...


You can always ask for variance, I would suspect your going to need one just to have PV in your home. If thats not the route your taking then hardwire them in, pass your inspection. Turn the off and put up a battery powered unit next to it.


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## Explorer (Dec 2, 2003)

My smoke detectors are hardwired and if power fails they switch to a internal 9 volt battery backup automatically.


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## Willowdale (Mar 19, 2007)

Explorer said:


> My smoke detectors are hardwired and if power fails they switch to a internal 9 volt battery backup automatically.


Yep, I might experience a selective power failure on that circuit.


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## greg273 (Aug 5, 2003)

Check the fine-print on those hardwired smoke detectors, some will NOT work with modified sine-wave inverters. In that case, wire them together, but DO NOT hook up power to that circuit. That will keep them inter-connected, (when one alarm sounds, they all sound), but will not fry them. I spoke to the technician at the place that makes them, he explained the hows and whys of this, even sent me a free smoke detector for my troubles. ( of course, it was the same model, so I still cant use my mod-sine inverter with it). 

Our building code says the same thing... I have already had my electrical inspection, the inspector didnt ask if there was power to the smokes, just saw that I had them wired properly, and that was that. His eyes glazed over when I started explaining the solar panels/charge controller setup, so I just directed his attention to the more familiar (in his eyes) AC load panel and standard wiring. He said 'good job', gave me my 'passed' sticker and left within ten minutes.

PS, I have had these 'hardwired' smoke detectors running on strictly 9Volt battery power for several months now, and they are still working fine. Seem to last as long as any other detector on battery power.


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## texican (Oct 4, 2003)

Do you have a code inspector inspecting your house on a regular basis???

If you're in a socialist section of the country, hook the hardwired detector up to a dedicated circuit... get your inspector happy... and promptly disconnect it. If the inspector is coming out on a regular basis, I'd leave that part of the country...

I agree, I'd never have any kind of phantom load killing (using) my inverter power... first off, running an inverter is inefficient, for what's basically a 9volt dc load... but I'd not have my smoke detector hardwired even to my battery bank... If there's a fire in your home, odds are it's going to hit your battery grid first (lots of explosive gasses, high voltages, switching), and if it 'goes', your smoke detectors are back to working on batteries anyhow....

Last park service housing I lived in had hardwired connectors... Had some nice sparks fly when I reached up and grabbed the smoke detector and yanked it out of the ceiling... they'd went from battery powered to hard wired... Ooops!


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## greg273 (Aug 5, 2003)

texican said:


> Do you have a code inspector inspecting your house on a regular basis???
> 
> If you're in a socialist section of the country, hook the hardwired detector up to a dedicated circuit... get your inspector happy... and promptly disconnect it. If the inspector is coming out on a regular basis, I'd leave that part of the country...
> 
> ...


 If you ever want that smoke detector to work again, you wont hook it up to a live 120volt AC modified sine-wave inverter, even for a moment. The technician said it would take about 10 seconds to fry the circuits on the detector. Something about peak voltage mismatch. So possibly hook it up correctly, just leave the breaker PERMANENTLY off, or save a breaker and just convieniently forget to hook the black (hot) wire up somewhere in the wall. Possibly in a junction-box of its own. (Any wire splices are supposed to be in accessable junction boxes anyway.)


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## Willowdale (Mar 19, 2007)

Tex, I'm doing significant work on the place to get an occupancy permit, and I'll need an electrical inspection as part of that. It never had wiring or indoor plumbing, not to mention the roof was out and it was filled with pigeons  My county is small and everyone knows everyone's business, so I could never get away with making the ruin (a well known place locally) habitable again without the county knowing. Hell, I'm distant kin and neighbor of the building inspector, the well and septic contractor and the electrical inspector!

Once it's passed code, no one will come out again.

Good to know about the modified sine wave AC. I'm planning to get an Outback true sine wave inverter, but I'm going to have to save money somewhere in this system and that might end up being the place. *sigh*


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