Interesting electrical problem related to circuit wired smoke detectors

[Gene South]

I went on a one-year warranty inspection today, meaning the oneyear warranty was about to expire on a new home and the homeowner wanted aninspection to find any last minute problems so he could give them to thebuilder. Before I arrived, the homeowner called and told me his house had a problem and that was whenever some devices were turnedon, his smoke detectors sounded. Ithought for a moment, he meant turning the heat on and maybe the dust in theducts somehow triggered the smoke detectors. When I arrived, I discovered it was not related to the heating system. Heexplained that he had a FAX machine in his home-office and whenever he receiveda FAX, the smoke detector in the opposite end of the house sounded for a few momentsand stopped. The smoke detector did not continuously sound, only briefly. He said the builder sent an “Electrician” whoinvestigated and determined the electrical outlet for the FAX machine was onthe same circuit as the smoke detectors, so they installed a new outlet in hisoffice on a separate circuit. He thoughtall was well but later he noticed when his wife plugged in the vacuum cleaner intoa different wall outlet in his home-office and turned the vacuum cleaner on; the smoke detector startedbeeping again. This smoke detector was nowhere near the home office but apparentlyon the same circuit. I asked him if hecould repeat the scenario and he said yes and went and retrieved the vacuumcleaner from the closet, and plugged it in to an outlet in his home office andturned it on. The smoke alarm began to beep. I witnessed this twice in succession. Apparently the amp draw is such that the smoke detectors think they arelosing power and emit a beep. I havenever run across this and wondered if other had seen this?

The photos are off the house, the fax machine. and the vacuum. Vacuum and fax machine are in the same room.






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[Nolan Kienitz]

GS,

Do some research on AFCIs. Maybe (just "maybe"), if they are all on the same circuit the AFCI involved could be sensing something off kilter.

AFCIs have a bunch of stuff going on inside them and maybe one of the 'bunch of stuff' is not quite right.

This is a WAG on my part, but one never knows.

[Gene South]

Hi Nolan, actually I think you are on target. Even though the home office was not a bedroom, the builder had it wired to an AFCI. Here are some photos. I suspect it is AFCI related as you do. For a trouble shooting test, I recommended to the builder to remove the AFCI's and replace them with regular breakers just for testing. Then with regular breakers installed in the panel, plug in the vacuum cleaner. If the problem goes away, then it points to the AFCI being the issue. Then if the AFCI's are remounted in the panel and the problem returns, then it is AFCI related. At that point I would pull the EATON brand AFCI's and replace then with a different manufacture AFCI. See the photos.

Thanks, Gene

[Jim Luttrall]

Might just be the smoke detector. Much easier to swap to test (although that is not our problem.)
Just thinking that smoke detectors are designed to communicate with each other and there may be something askew in the detector that is interpreting the function of the other appliances as something that is "talking" to them. Again, just WAG.

[Nolan Kienitz]

GS,

Most of the new home finals and warranty HIs I've come across recently have the full complement of AFCIs installed ... of course it depends upon the local AHJ and what they require.

Some ... as indicated by your 2nd round of images ... only require the AFCIs in the "sleeping areas". An office can be considered a 'sleeping area' as it has a closet ... typically.

Also most all the SDs are put on the same AFCI from what I've run across as well that is usually shared with a bedroom ... in this case maybe the office.

[Jim Luttrall]

By the way Gene, do you have to use such small font? I had to boost my screen size just to read it... and yes I do have old eyes but no that is not the problem.

[Rick Cantrell]

Electronics have a shield to keep out RF signals.
Many times the shield may be nothing but the paint.
If the shield is not working funky things happen (Funky is a technical term)
Try replacing the detector with one of the other detectors.
Easy and cheap. See if the problem follows the detector or stays in the same spot.

[Gene South]

Hi Jim, I will enlarge the fonts for the next post.

I think the homeowner told me the electrician swapped the smoker detectors prior to installing a new outlet circuit. The smokes in this room was pretty high. A 14 foot ceiling I think.

[John Kogel]

If the AFCI is not tripping, I would forget that idea.

Fax machine and vacuum draw a lot of current to start. My fax/copy machine was tripping my battery backup system so when that unit went haywire, it was actually shutting down my desktop computer, just to print a sheet of paper.

The electrician swapped in a new smoke alarm unit, but it's the same model. Easy to plug in without changing the base. Install a different model smoke alarm.

[Jim Port]

Then with regular breakers installed in the panel, plug in the vacuum cleaner. If the problem goes away, then it points to the AFCI being the issue. Then if the AFCI's are remounted in the panel and the problem returns, then it is AFCI related. At that point I would pull the EATON brand AFCI's and replace then with a different manufacture AFCI. See the photos.

Thanks, Gene

It does not point to the AFCI being at fault. It is just that the AFCI is detecting a possible flaw in the wiring.

Breakers need to be listed for use in the panel. You cannot install Brand A in a Brand B panel unless they a listed on the label. Typically the other brand will not be listed.

[Vern Heiler]

If the AFCI is not tripping, I would forget that idea.

Fax machine and vacuum draw a lot of current to start. My fax/copy machine was tripping my battery backup system so when that unit went haywire, it was actually shutting down my desktop computer, just to print a sheet of paper.

The electrician swapped in a new smoke alarm unit, but it's the same model. Easy to plug in without changing the base. Install a different model smoke alarm.

I agree with John, I have not heard of arc faults that could trip for just a second and go back to normal. My first guess would be a bad neutral connection, and my recommendation would be to replace the electrician as a first attempt at repair.

[Gene South]

I will report the findings when it is resolved. It is being worked on this week.

[Lon Henderson]

The solution is to stop receiving faxes. That is sooooo yesterday.

[Gary Burnett]

Jim is correct in not replacing breakers with another manufacturers. Eaton would probably void the warranty (since it says that in their panel). I'm leaning toward Vern's suggestion to replace the electrician.