AFCI tripping

Reply

  #1  
Old 05-23-13, 06:37 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: Dec 2005
Location: USA
Posts: 39,968
AFCI tripping

Nearly all my work is done on homes without CO, so no final electrical is connected. We work off temporary poles. Retrofitting a house with shelves tosay, one of my guys plugged in my Ridgid double miter saw into a receptacle and triggered it. Ran for one second and tripped the breaker. He called me in to check it out. It was on a bedroom circuit AFCI. I deducted that it was picking up the arcing of my saw's motor and shutting down. Removed it to the washing machine receptacle and all was well. Any thoughts on that?
 
Sponsored Links
  #2  
Old 05-23-13, 06:50 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,461
Makes perfect sense to me.

I've now seen all kinds of devices trip an AFCI breaker. Right down to laser printers due to their inrush current when the heater first fires up.
 
  #3  
Old 05-23-13, 07:15 PM
Nick D.'s Avatar
Member
Join Date: Feb 2013
Location: USA
Posts: 143
Do you know what generation and manufacturer these were?

It depends on those two variables how good or badly the AFCI will perform. Current AFCIs from a reputable maker like Seimens do not respond to series arcs, such as found in brush motors.
 

Last edited by Nick D.; 05-23-13 at 07:58 PM.
  #4  
Old 05-23-13, 07:56 PM
Nick D.'s Avatar
Member
Join Date: Feb 2013
Location: USA
Posts: 143
Originally Posted by Andrew Mills
Anything with a motor will set them off because of the arcing.
Brush motors should NOT trip good quality, current-generation AFCIs. Brush motors are, however, problematic with older and/or inferior AFCIs.
 

Last edited by ray2047; 05-24-13 at 06:57 AM.
  #5  
Old 05-24-13, 03:29 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: Dec 2005
Location: USA
Posts: 39,968
It's a new house, but I didn't even note the brand of panel. I was just curious if it was commonplace, which apparently it should not be with current types of AFCI's. One thing popped into my head.....when you let go of the trigger, a half wave rectifier turns the spinning motor into a generator in reverse for a blade brake, until the blade stops. Of course it could have been a bad breaker, too, who knows?
 
  #6  
Old 05-24-13, 11:12 AM
Nick D.'s Avatar
Member
Join Date: Feb 2013
Location: USA
Posts: 143
Originally Posted by chandler
One thing popped into my head.....when you let go of the trigger, a half wave rectifier turns the spinning motor into a generator in reverse for a blade brake, until the blade stops.
Is that your assumption for your tool or do you know this? It's not an implied feature, at least not in older power tools, say from the 80's.
I can't see why such a thing would trip an AFCI, though... defective or not.
 
  #7  
Old 05-24-13, 11:50 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: Dec 2005
Location: USA
Posts: 39,968
It may not be for this particular tool, as I have not taken it apart. I have repaired several of my radial arm/cut off and miter saws in the past that the blade brake failed on. Invariably I would have to go to Radio Shack and purchase a half wave rectifier and replace it. Not an assumption in general. As far as being an "implied" feature, probably not, but that's how it works. As soon as you deprive the spinning motor of current, it ceases using power and begins createing power in reverse as a generator. Thus the half wave rectifier. It falls off as the motor comes to rest.
 
  #8  
Old 05-24-13, 12:02 PM
core's Avatar
Member
Join Date: Jan 2007
Location: Des Moines, IA
Posts: 1,127
I would have to go to Radio Shack and purchase a half wave rectifier and replace it.
When's the last time you were at Rat Shack? Ask a salesperson for that and you're likely to get escorted out of there as a sicko. They may try to sell you a cell phone plan though.

In all seriousness, they never sold a half wave rectifier as far as I know. A couple of high power diodes, sure.

Chandler, in your saw, what happens to that power generated? Does it have a big resistor in there? I'm just curious because that brake sounds cool. I'm resisting the urge to wonder why it even needs a rectifier at all. Too late. No seriously I've never taken apart my own power tools.
 
  #9  
Old 05-24-13, 12:39 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,644
The fun thing at Radio Shack is too look up the Radio Shack model number on line first then when they say there is no such thing whip out the RS number.

I knew a TV repairman who back in the days of vacuum tubes sometimes would run out of a particular tube on a weekend and wasn't near a 7-11 where he could get RCA tubes but near a Radio Shack which carried their own brand of tubes. He'd buy four of the tube he needed. Try each, leave the one that worked in place and throw away the other three.

P.S. Yes, I really meant 7-11 the convenience store. Not only did they have a tube tester and sell tubes they rented TVs by the day.
 
  #10  
Old 05-24-13, 01:04 PM
core's Avatar
Member
Join Date: Jan 2007
Location: Des Moines, IA
Posts: 1,127
whip out
I'm just guessing mall security would have you following chandler right out of there.

I could be wrong.

In my old city (Des Moines) there was _one_ store (out of like 10) that still sold simple things like resistors. It was right next to an urban college. You know, where nobody has any money. One wonders what they were thinking. The college wasn't the type for engineers. *cough* *liberals* *cough*

That was probably 5/10-15 years ago, I'd be curious what the status is of everyone's Radio Shacks out there. Perhaps that should be the subject of a diff thread.
 
  #11  
Old 05-24-13, 01:23 PM
core's Avatar
Member
Join Date: Jan 2007
Location: Des Moines, IA
Posts: 1,127
P.S. Yes, I really meant 7-11 the convenience store. Not only did they have a tube tester and sell tubes they rented TVs by the day.
What year was this? Awesome 2-line story. I wasn't born then but I thought I was well-versed in the tube era. I have never heard normal-Joe stuff like this. Wow. But I'm guessing this 7-11 was NOT normal. We would have known as kids. We eventually had a color television set.
 
  #12  
Old 05-24-13, 01:28 PM
Nick D.'s Avatar
Member
Join Date: Feb 2013
Location: USA
Posts: 143
Originally Posted by core
Chandler, in your saw, what happens to that power generated? Does it have a big resistor in there? I'm just curious because that brake sounds cool. I'm resisting the urge to wonder why it even needs a rectifier at all.
In electric braking, a countering or stationary (depending on motor type and brake design) magnetic field is introduced into the motor.

For series-wound universal motors (most power tools), the braking current is half-wave. In AC induction motors, braking current is DC. The cool thing about AC motor braking is that it only takes a relatively small amount of DC current. Just 12v at a few hundred mA will stop a small unloaded motor in a split second.
 
  #13  
Old 05-24-13, 02:57 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,644
What year was this?
About '72 when I heard the story from an old time repairman in a course I took. Unfortunately it was a government training course the Navy suggested after my discharge. Supposed to prepare me for a job. It didn't. It was seriously flawed. Still teaching tubes when transistors were becoming the norm. Worse it was so dumbed down most of it was stuff I'd known since I was a teenager. Literally read the whole text book the first week of the six month course and was surprised/shocked the book was intended to be taught over a six month period. Was so bored after two month the instructor let me take the final exam.

Back in the '50s and '60s growing up in the south all 7-11s rented TVs as far as I know. Fun fact: No AC back then. The hole front of the store was garage doors that were left up during business hours in the summer. Fun history fact: The one I remember moved across the street to Miller county (Arkansas) so it could sell beer since Bowie county (Texas) was dry. I always wondered if it moved back when Texas started the lottery.
 
  #14  
Old 05-24-13, 04:14 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
I remember the garage doors across the front, but I don't remember the tubes for sale or the rental TVs. Maybe it wasn't all 7-11s. OTOH, the first time I remember encountering 7-11s was when we moved to the Big City in '55. I think they started down your way and spread out to the rest of us.
 
  #15  
Old 05-24-13, 05:08 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: Dec 2005
Location: USA
Posts: 39,968
Tube testers?? Sure, at every convenience store. They also had some of the more common ones in stock behind the counter. Remember that well. Heck, I remember when Waffle House CEO decided to give all his employees Christmas off. Only one problem...Waffle Houses were built without locks. They never closed, so why have locks. Had to install locksets to close the stores. Not sure how widespread that was, but in Atlanta it was common.
 
  #16  
Old 05-24-13, 05:24 PM
CasualJoe's Avatar
Member
Join Date: Jan 2010
Location: USA
Posts: 9,213
Current AFCIs from a reputable maker like Seimens do not respond to series arcs, such as found in brush motors.
If I remember correctly current NEC requires the use of combination type AFCI protection which means they detect both parallel and series arc faults, but the earlier version AFCI breakers only detected parallel arc faults. 10 years ago it was not uncommon for a vacuum cleaner to trip an AFCI breaker. As I recall, the earlier version AFCI breakers are still available and are a little less expensive than the combination type.
 
  #17  
Old 05-24-13, 06:31 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
I do remember tube testers in some stores, now that you say it that way, Larry. Something about that phrase triggered it. My memory, now that I'm in touch with it, includes some stock out in the open - maybe on wire shelves below the tester.

I don't remember what store or stores though. The Feed and Seed, or the dime store?
 
  #18  
Old 05-24-13, 07:12 PM
core's Avatar
Member
Join Date: Jan 2007
Location: Des Moines, IA
Posts: 1,127
includes some stock out in the open - maybe on wire shelves below the tester
Yes I can totally see this on the shellf: Coke, Doritos, tube tester. Right next to the Chia Ovulator? Pic or didn't happen.
 
  #19  
Old 05-24-13, 07:21 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,644
 
  #20  
Old 05-24-13, 07:36 PM
core's Avatar
Member
Join Date: Jan 2007
Location: Des Moines, IA
Posts: 1,127
Whoa that looks serious. Keep your winkie away from the plate voltage. This would have had a chance before Asteroids
 
  #21  
Old 05-24-13, 07:37 PM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 32,644
And heres how you knew which tube to test.


Sorry Larry for running your post off the rails.
 
  #22  
Old 05-24-13, 07:48 PM
core's Avatar
Member
Join Date: Jan 2007
Location: Des Moines, IA
Posts: 1,127
That's hilarious in the illustration... Donna Reed housewife testing a tube like it's a weekly occurrence. Yeah right! My, how things could have ended up.
 
  #23  
Old 05-24-13, 08:27 PM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: NJ - USA
Posts: 43,461
Donna Reed housewife testing a tube like it's a weekly occurrence.
Well....you know what.... it was a weekly occurence with some old tube sets. Picture a TV with twenty tubes in it. Great source of heat in the winter. Back then like 90% of the repairs were able to be handled by a DIY'er.

And then Motorola under the Quasar name came out with the "works in a drawer" It was an early solid state color TV where the chassis slid out from the front and the homeowner could replace one of ten solid state modules depending on the problem. (and they did have problems)

I could go on all night.

To get back on topic... I have a particular customer that uses large laser printers in his bedrooms. He routinely trips under one year old Square D QO AFCI breakers in two of the bedrooms. I have replaced them both and they still trip.
 
  #24  
Old 05-24-13, 08:44 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
That's the high-rent model, Ray. And an early example of "vendor stocked," I think, because these were always one-company setups. RCA was one, IIRC.
 
  #25  
Old 05-25-13, 06:05 AM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: Dec 2005
Location: USA
Posts: 39,968
Ray, trips down memory lane are never off topic, to me. That's exactly what I remember at Sim's Pharmacy when I was younger....much younger
 
  #26  
Old 05-25-13, 06:39 AM
Tolyn Ironhand's Avatar
Group Moderator
Join Date: Nov 2007
Location: Twin Cities, MN
Posts: 11,981
Back to the issue at hand.

First thing I would do is to try another high draw tool like a shop vac, or another saw, and see if that will trip the AFCI. Also, try the saw on another receptacle on the same circuit and see if that will trip it. There might be a slightly loose connection someplace the does not arc until a good sized load is put on the circuit.

We did a new house that a circuit was fine until a shop vac was run on it. Then it would trip right away. Turned out the HVAC guy used a framing nailer to nail on his returns with 3" nails. Not good for NM cables.
 

Last edited by Tolyn Ironhand; 05-25-13 at 07:43 AM.
  #27  
Old 05-25-13, 02:33 PM
chandler's Avatar
Banned. Rule And/Or Policy Violation
Thread Starter
Join Date: Dec 2005
Location: USA
Posts: 39,968
I'll check connections when I go back to make sure they are solid. It is apparently a bedroom circuit with this outside GFCI receptacle on it. Only 4 receptacles, so it should be easy to check.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
'