AFCI Issue...

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JFletcher said:
Damned fine troubleshooting!

Was in a building yesterday that when the bathroom door slammed, the walk-thru metal detector would go off. I recommended a new door closer, or slow down the hydraulics on the existing one, so it closed softer/slower. No idea why it set off the metal detector, just found the cause of it going off.
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If anything like the metal detectors that are designed to detect metal in a 50 pound bag of food grade product - I am not surprised. They are sensitive to a lot of things and the smaller the piece of metal you wish to detect the more false trips you will get from other things.
 
kwired said:
If anything like the metal detectors that are designed to detect metal in a 50 pound bag of food grade product - I am not surprised. They are sensitive to a lot of things and the smaller the piece of metal you wish to detect the more false trips you will get from other things.
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I dont know the differences between a walk-thru designed for security and one on a high-speed production line designed to find a 10-32 nut or trash metal in the food. I know the one I walked thru beeped with a penny in my pocket, so I guess it's pretty sensitive. I imagine high vibrations, loud noises, RF, etc could set off either.

With a walk thru, if you set it off you usually get "wanded" with a hand-held unit that's much less sensitive. It wont detect metal implants or screws or a lighter, but will pick up a knife or gun, which is what most places are concerned about.
 
JFletcher said:
I dont know the differences between a walk-thru designed for security and one on a high-speed production line designed to find a 10-32 nut or trash metal in the food. I know the one I walked thru beeped with a penny in my pocket, so I guess it's pretty sensitive. I imagine high vibrations, loud noises, RF, etc could set off either.

With a walk thru, if you set it off you usually get "wanded" with a hand-held unit that's much less sensitive. It wont detect metal implants or screws or a lighter, but will pick up a knife or gun, which is what most places are concerned about.
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My experience is the food industry, and primarily detecting metals in a 50 pound bag of product.

Different moisture, fat, etc. in products makes a difference in how small of a metal object can be detected. Calibrate the machine for one product and then run a different product through it and it may reject an otherwise good bag of product, because the moisture content gives it a different density.

Is easier to calibrate it to detect a specific foreign object in a 10 pound bag then to detect same object in a 50 pound bag as well.

So I have to imagine a walk through detector would need to be calibrated to detect certain sized objects and if you went too small with what you want to detect you would easily get a lot of false alarms. A 60 pound child would probably set it off carrying a particular test object, but make a 275 pound person go through and they may set it off even with no metal objects if calibration is too sensitive.
 
al hildenbrand said:
Sure, but what you aren't answering is the question about the dwellings in that complex. . . How many of the individual dwellings are given full 3-phase five-wire panels (not just 208 / 120 Volt single phase)?

In my long career, I have seen only one single-family dwelling that had a three-phase service, and it was one weird animal as it was the SECOND service. It was 30 Amp 240 Volt THREE-WIRE three-phase from an open delta transformer bank, installed for pump motors. The FIRST service was 100 Amp 240 / 120 Volt three-wire single-phase from an entirely different transformer.
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Tis rare, but in older parts of certain cities you will find remnants of a 3 phase high leg 240/120 service off an open delta serving or had served large homes. This is because many of the first AC systems installed in resi were 3 phase.
 
I think I'm going back tomorrow for an unrelated issue. I'll double check the panel again and report back. Thanks for all of the great information and insights.
 
1793 said:
I ran across a residential panel that my customer is complaining of a 15a 120v AFCI breaker randomly tripping. When I removed the cover I noticed the only three AFCI breakers in a row. As I looked into it closer I noticed that someone had grouped all three AFCI neutral pigtails together to a single #14 neutral.

I don't know that much about AFCI's so could this be an issue?

Thanks
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Back in "the day", I remember Siemens AFCI's had to be staggered to prevent heat build up and tripping.:eek:hmy:
 
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