AFCI problems in new home

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MarkDPSU

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I just moved into a new home, which has Seimens AFCI breakers installed for each room (except kitchen, baths and basement). My vacuum cleaner trips these breakers. My heating pad trips these breakers. Sometimes, but rarely, a light switch trips these breakers. Apparently, these breakers are a new requirement in MA, and this is only the third house in which this electrician has installed these type of breakers. The electrician claims the wiring is correct and the breakers have been known to have problems with vacuum cleaners. Seimens said, they do not know of any problems with their breakers concerning vacuum cleaners, and some electricians have been wiring incorrectly for years but have not had problems until the AFCI started to be used. Right now, I am trying to determine how to prove whether the breaker is really sensitive or the wiring is incorrect.
Question: Is it wise to make a test box wired correctly with a different AFCI, and plug in the questionable equipment to help determine if it is the equipment (vacuum/heating pad)? That really won't diagnose the problem completely, but it may provide information toward getting the electrician to look at his wiring or switch to different breakers. I am open to any helpful hints that may help me determining if it is a wiring problem without doing the electricians work. After all, itis a new home under warranty.

Thanks
 
Mark, you are an electrical engineer and, no doubt, know all the theory behind the AFCI products. However, you are a do it yourselfer so we can not give you specific advice of the "how to" nature. We can give you some advice on how to work with your electrician and what can be done with your AFCI circuit breakers.

Welcome to the forum. :smile:
 
AFCI devices aren't really complicated to install so a competent electrician shouldn't have any real problems with their installation. If you're only have nuisance tripping problems with specific appliances I would doubt that they're wired incorrectly.
 
Try plugging the vac into dif. receptacles fed from dif. breakers. If it trips everytime there's a vac problem. I've had a problem with bathroom fans tripping AFCIs.
 
081024-2205 EST

MarkDPSU:

Do breakers trip on other circuits than the circuit with the load causing the trip?

Vacuum sweepers use a universal motor. This type motor has brushes and these will normally produce some arcing. Switches will produce some arcing. The amount will be load dependent. Fluorescent lamps may produce large line transients when switched.

I have not played with AFCIs so I have no feeling of signals that might cause false triggers.

My guess it is very difficult to design a device to sense arcs that are dangerous and yet avoid false alarms from normal loads.

I am also going to guess that Seimens may have a problem. We need to know what signals the AFCI manufacturers are using to define a positive signal verses a normal signal.

In a post a while back I listed a source where I found limited information on a signal signature. But this was quite limited.

Take an 8 ft Slimline fixture and repeatedly plug and unplug this on an AFCI circuit and see if you can force tripping. If it causes tripping, then Seimens has a problem.

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This is all bunk. Everybody knows AFCIs have been perfected and NEVER nuisance trip. :rolleyes:

Welcome to the wonderful world of the NEC, we've never met a manufacturer that couldn't con us into selling their products. :rolleyes:
 
It is possible that it may not be the arc causing the problem, may be a leakage to ground. Try it in a ground fault receptacle and see if it trips, if so you may have a defective appliance.
 
MarkDPSU said:
I just moved into a new home, which has Seimens AFCI breakers installed for each room (except kitchen, baths and basement). My vacuum cleaner trips these breakers. My heating pad trips these breakers. Sometimes, but rarely, a light switch trips these breakers.

Thanks
Click to expand...

AFCIs can drip due to leakage current, a parallel arc or if a combination device -a series arc. Wouldn't it be nice if they provided an indicator of some sort to let you know which it "thinks" it detected?

I suspect that a vacuum cleaner could look like either a series arc "due to brush arcs" or a parallel arc due to inrush current on first turn on.
Does your vacuum only trip at first turn on?

What I found interesting is that a heating pad trips them. Does the pad trip when it is cycling power due to a thermostat, at power on, or randomly?

It should be fairly easy to eliminate leakage as a possible cause with a simple differential current measurement.

If a person were really interested in knowing the cause of the issue you might temporaily install a "soft start" circuit on the offending loads. If the soft start circuit limited the inrush current to under 75 amps then you could possibly isolate the parallel arc as the cause.?
While this might isolate the cause it would not provide any permanent resolution.
 
Each manufacture of AFCI breakers should sell a small device that is based on there unique circuit breaker design that you can plug each household appliances into, to check for nuisance tripping. Is it the UL listed AFCI breaker or the UL listed appliance ! I personally feel that the UL listing on a lot of mass produced appliances will need to change with the times. If I had a AFCI circuit that worked just fine with a TV or Lamp, but tripped with a toaster or vacuum cleaner, I would say its time to redesign some appliances. How many out there have fixed a household appliance and said to yourself (The Engineers that designed this sure spent a lot of time on designing the cheapness of manufacturing the parts then they did the longevity quality of the electrical parts !) I'm glad the AFCI has come along so as time will tell, we won't be held in contempt for every UL approved appliance. Did you know the minute you take someones UL listed appliance apart, you have possibly void its UL listing.

But for some of the near years to come, I think its gonna be a bit of a nuisance for us Electricians, explaining that its not always our fault.
 
and AFCI bkr will trip if and when it feels like it. i dont think anybody can explain the whys of some of the things i've seen trip one, not even Tesla.
 
They trip for a reason. They see certain signatures that they may not like and they let go. We can call it poor design, but they did their job, even if it's not how we wanted them to.

An eblanket letting one go? Hmmmmm:cool: Like to look at that.
 
ELA said:
AFCIs can drip due to leakage current, a parallel arc or if a combination device -a series arc. Wouldn't it be nice if they provided an indicator of some sort to let you know which it "thinks" it detected?
Click to expand...


http://images.google.com/imgres?img...n&safe=off&rls=GGLG,GGLG:2007-39,GGLG:en&sa=N

Perhaps it is not much but it is better than nothing

The new Siemens Combination Type AFCI includes unique Siemens exclusive and patented LED trip indicators. These indicators provide a valuable analysis tool to help electricians and home owners alike pinpoint the type of problems that cause the AFCI to trip, and therefore save valuable time during troubleshooting and repair. These indicator LEDs are located near the handle of the breaker and will distinguish arcing faults, arcing to ground and overcurrent conditions.
Here is how the trip indicators work:
The LED indications will appear for 5 seconds each time the AFCI is turned ?ON? up to 30 days after the last trip. One LED will be illuminated if the last trip was a result of an arcing fault. Two LEDs will be illuminated if the last trip was a result of an arcing fault to ground. No indication will be displayed if the AFCI trips as a result of an overcurrent condition. The last known trip indication can also be manually cleared from memory to assist with verifying resolution of the problem
Click to expand...
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It is nice to see that some manfacturers are supplying an indication of the reason for tripping. I think it should be a requirement for all.

Gar,
AFCI's drip very, very slowly.:D
Almost imperceivable to the human eye.
 
I'd probably try a different brand breaker and see if it trips. I'd also check that they aren't single AFCI's on multiwire branch circuits.
 
afci's will trip if theres a shared neutral. have your electrician check for those. also he should megger the circuit too. another thing check for neutral to ground connections sometimes the bare egc can hit the neutral in a box by accident
 
It would be very interesting if you could get the elctrician to make a
"test box" with another brand of GFCI and see if the same equipmenmt trips that brand also.
 
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