Plug in carbon detector?

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Hello. There is an existing house that is without power. Since the power has been off for more than a year, in order to get the power turned back on the city requires that there be GFCI protection for devices near sinks, smoke detectors installed in each bedroom and outside of each bedroom, and carbon detectors installed if there is gas in the house or it has an enclosed garage. (the POCO also will not hook up the power if there is a 60amp meter base, and rightfully so) They have updated the required items, but they have a plug-in type carbon detector. Is that legal? I've never seen one, nor can I find a code reference for it. I'm assuming that it must follow the same rules as the smokes, but I'm asking you guys to be sure lol

Thanks,
Kenny
 

GoldDigger

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First of all, it is properly a carbon monoxide detector. But we all know what you mean.

I believe that where a Code requires a CO detector it must have at least a battery backup so that it can still work when the AC is off.
I know that there are also purely battery powered units. And since the sensing element has a limited lifetime regardless of use history some of them have non-replaceable batteries.
 

GoldDigger

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I understand that, but is it permissible to have the carbon monoxide :thumbsup: detector located near the floor? As in, plugged in to a receptacle 13" a.f.f.?
Plugged in as in located there rather than cord attached?
I do not think so. CO is lighter than air so the concentration will be highest at ceiling level.
People intending to use a wall wart style CO detector would have to deliberately install a receptacle outlet in a location specified in the CO detector instructions.
That is certainly possible in new construction, but unlikely in old work.

I did not realize just what you were originally asking.

FWIW carbon is heavier than air, not being a gas, and so it would pile up on the floor. :angel:
 

rcarroll

Senior Member
The requirement for a CO detector is in the building code. In my area, we allow a hard wired, battery powered or a plug in type.
The code does not care if the CO detector is installed on the ceiling, wall or down low.
This, of course, is without any local ammendments.
 

gadfly56

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New Jersey
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Professional Engineer, Fire & Life Safety
But is does require that you follow the installation instructions of the detector, which do tell you where you can put it.

See also this site for a general discussion of location.

Kidde makes a version of their Nighthawk that plugs into your standard height receptacle.

As for CO being lighter than air, this is really a non-starter. Your faulty appliance is not going to pump out a plume of CO where the bulk density would really make a difference. Any CO is going to be well mixed with the local air to a pretty uniform consistency merely by the action of the furnace fan, or people stirring the air as they walk by or the normal draftiness of your typical home.
 

wwhitney

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Berkeley, CA
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CO is lighter than air so the concentration will be highest at ceiling level.
I don't think that's correct. The density of a gas is proportional to its molecular weight. Air is primarily nitrogen (molecular weight 28) and oxygen (molecular weight 32). Carbon monoxide also has a molecular weight of 28.

Despite the differences in molecular weight, the oxygen and nitrogen in air are well mixed. We don't worry about all the oxygen in the air accumulating near floor level. Since carbon monoxide has the same molecular weight as nitrogen, I'm pretty sure the carbon monoxide will diffuse well through the air.

Of course, for a localized source of carbon monoxide, I don't know how quickly the carbon monoxide will diffuse. So there will be some benefit to having the detector near possible sources of carbon monoxide. I don't think the diffusion will be any faster in the upward direction, however.

Cheers, Wayne
 

Hendrix

Senior Member
Location
New England
I understand that, but is it permissible to have the carbon monoxide :thumbsup: detector located near the floor? As in, plugged in to a receptacle 13" a.f.f.?
Yes, I think so. CO has a molar mass of 28.0 and air has a molar mass of 28.8. Therefore It will mix well with air and, IMO, not make a difference weather it is mounted high or low.
 
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