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Walter Gregg; PO Box 21693; Juneau, Alaska 99802; 907-586-6978 (voicemail)

September 2, 2022

U.S. Consumer Product Safety Commission
4330 East West Highway
Bethesda, Maryland 20814

The Koabbit Gas & CO Detector, ASIN B092R9BR7T

I purchased the above- identified carbon monoxide and explosive gas alarm via Amazon.com (amazon.com/ Monoxide-Detector-Natural-Combination-Combustible/ dp/ B092R9BR7T). The bar code on the box itself is X00283NWTJ.

I chose it because because the comparable FirstAlert and Kiddie units use wall transformers that cover up adjacent outlets. This one has a far more convenient lamp cord style connection. It's sold as meeting UL1484 (residential gas alarms) and UL2034 (residential CO alarms) and has a digital CO readout.

This is just an information report, not a complaint. I like the product and I think it can save many lives as intended. However, I discovered that it doesn't bear a third-party US recognized electrical safety listing (e.g. CSA, ETL, UL). At least in my state such a listing is a statutory requirement for retail electrical sales (AK Stat §45.45.910 (2018)). Additionally, any backup battery inserted gets overcharged to the point it will get notably warm, never a good sign. Indeed, some people will certainly insert a primary carbon-zinc, alkaline, or even lithium backup battery, having no idea that there's a risk of leakage, exposion, or fire. The warning about this should be more explicit or alternatively the charging feature removed so the optional backup battery could be any available type.

In any event, it's just possible it might merit CPSC communication with the maker to help them come into full compliance with our often obscure rules. Below are my notes.

Thank you,
/s/ Mailed 09/05 @FB outside box
Walter Gregg

Thoughts on the Koabbit Gas & CO Detector

I chose this carbon monoxide and explosive gas detector because it has a digital readout and plugs in with a conventional lamp cord style plug. The comparable FirstAlert and Kiddie units use wall transformers that cover up at least one adjacent outlet. That's very inconvenient. This alarm is sold as meeting UL1484 (residential gas alarms) and UL2034 (residential CO alarms) and has a digital CO readout, so it should do the job just fine.

In my opinion, you also need a fully battery operated CO or CO/Smoke alarm. This is because explosive gas detectors draw too much power for batteries to last more than an hour or three. It's important to have CO detection during a prolonged power outage. It's only when the flashlights dim and it starts to get cold that someone might start a kerosene lamp or heater inside. The same applies to someone starting a portable alternator in the driveway outside where the pressure differential could draw death inside. A separate battery operated CO detector covers this. If you have one, in my view, you don't need a backup battery in the plug-in explosive gas/CO alarm at all.

You must never use primary carbon zinc, alklaine, or lithium backup battery in this unit. There's a barely visible but extremely important note molded into the battery compartment:

WARNING: Please use 9V rechargeable battery only. Other batteries may cause disorder operation or even explosion.

In my opinion you shouldn't put a rechargeable battery in it either. In the first place, you don't need that if you have a separate battery-only detector. In the second place, it has no end of charge cutoff and the continuous charge is so high the battery gets noticably warm. At best, that encourages premature battery failure and leakage.


I was surprised to discover that the device doesn't bear a UL mark or that of the Canadian CSA or Intertek ETL. Technically, Alaska statute requires that new electrical devices cannot be sold at retail without the mark of an independent testing agency. This device only bears a CE mark. As I understand it that's a self-certification that it does meet European electrical safety standards. So I'm not particularly concerned, but I think they may have missed a regulatory requirement.

An independent testing lab would probably have highlighted the risk of providing charging current where primary batteries might be erroneously inserted. It would probably have noted that rechargeable batteries aren't interchangeable yet no type is specified. And it would probably have noted the apparently excessive charge rate.

Specifically, for nickel-based rechargeables, it's rather widely accepted that the maximum safe continuous charge where there is no end of charge detection doesn't exceed 1/10 of capacity. Thus in '9v' batteries, an obsolete standard 120mA nickel cadmium should be limited to 12mA. For the high capacity 140mA version the limit is 14mA. For the standard 175mAh NiMH it's 17.5mA. For the high capacity 250mAh version it's 25mA. But what I have measured here is that the charge rate never drops below 65mA. That's 2.6 to 5.4 times in excess of the maximum safe charge rate. One wonders about the potential effect on Lithium rechargeables. This is why I won't use a backup battery of any type in this unit.


The device itself bears no mark confirming that it meets UL1484 (residential gas alarms) or UL2034 (residential CO alarms). But the box itself has a bar code sticker identifying it as a 'Combination Natural..itchen/Home,UL2034' device. So I'm assuming it does meet the requirement(s).


The device has a low pitch siren rather than a high pitched beep. To me, that's a huge plus. To be sure, it's only about 110 decibels at the device or 90 decibels a foot away. The First Alert CO400 is about 125 decibels at the device or 106 decibels a foot away. But the First Alert is at 3,300 Hertz. And way back in 1940, before the advent of heavy metal, rap, and rock, it was found that men 50-59 years old had already lost 26 decibels of hearing at 3,520 Hertz (IT&T 1975).

IT&T. 1975. Reference Data for Radio Engineers,. p37-25. Quoting from Steinberg, J.C., Montgomery, H.C., and Gardner, M.B. 1940. Results of the World's Fair Hearing Tets. Journal of the Acoustical Society of America. Vo. 12, no. 2, Oct. 1940, fig. 3, p 293.

Almost every man over 50 has seriously impaired hearing. Don't believe it? Ask their wives. For these men, the Koabbit is effectively at least 10 decibels louder than the First Alert. And for a great many men today, the high frequency hearing loss is profound. For them, the First Alert might as well be an ultrasonic dog whistle. I probably shouldn't expand on that view. Still, regardless of regulatory requirements, this is something the Koabitt got right. Other manufacturers should take note.


The device bears no FCC certification or OEM compliance statement regarding unintentional radiation. The FCC rules are so lenient that they're almost meaningless if you like to listen to outside broadcast stations or shortwave. They were probably written when spark transmitters were still in use. But still.

The Koabbit is producing broadband hiss centered at 174 kilohertz (kHz) radiating from the electronics, plus broadband buzz across the entire range that rides the power line.

For comparision, an old First Alert CO615 screams a tone of about 1,400 Hertz all across the low frequency dial, peaking at about 400 kHz. It also bears no FCC statement.

Worthy of note is that a new battery operated First Alert CO400 appears to make no radio noise at all. It also bears no FCC marking but the instructions claim part 15 class B compliance.

I now have an ac-powered Koabbit gas / CO detector downstairs outside any direct draft. I don't use gas, but neighbors have propane, which is heavier than air, so it's mounted just 3 feet above the floor. I also have a battery- powered First Alert CO detector upstairs, outside of any direct draft, not too close to humidity sources, but within 10 feet of the bedroom doorway.

This seems like overkill in what's now an all-electric house. But when the Taku is blowing 75-100 knots, it's below 0F, and the houses are nearly uninsulated, an outage longer than 1-1/2 hours, though exceedngly unlikely here, could be catastrophic. And we're not very patient. Not really. People break out the candles. The gas-powered alternators. The kerosense heaters. Who knows what might not be tried. Having sentinels on guard against stupidity is important. I think the Koabbit can be an important part of that protection. But it needs a wee bit of attention to inconvenient statutory details, in my opinion.

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