ARC Fault puzzle

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shared neutral?

shared neutral?

Sidebar: Shared Neutral Applications
Single-pole AFCIs can't protect circuits in which the neutral (grounded circuit) conductor is shared or mixed because current flowing out and returning is monitored for the presence of arcing faults. When single-pole AFCIs are applied, the circuit must have a distinct hot and a distinct neutral conductor. Otherwise, the AFCI can't distinguish arcing ground-fault occurrences. General availability of a 2-pole AFCI should be expected at some point in the near future since the technology is readily capable.
 
billsnuff said:
Sidebar: Shared Neutral Applications
Single-pole AFCIs can't protect circuits in which the neutral (grounded circuit) conductor is shared or mixed because current flowing out and returning is monitored for the presence of arcing faults. When single-pole AFCIs are applied, the circuit must have a distinct hot and a distinct neutral conductor. Otherwise, the AFCI can't distinguish arcing ground-fault occurrences. General availability of a 2-pole AFCI should be expected at some point in the near future since the technology is readily capable.
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If this were true then I don't think the circuit would work for an hour as the op says.

DP arc faults are available now by some manufacturers.
 
I replaced the arch with a standard breaker...no problems. Put the arch back
problem returns. The flashlight is the same as the other 116 units. Only 5 rooms are giving me a problem. I am going to take these circuits apart one more time and replace the breakers.....again. This is not a health care facility, maybe limited care, depends on the way the AHJ reads 517.
The archs were a note on the print, Not the 2005 NEC
There is a small kitchen, no stove, just microwave and sink , would you (anyone) consider this a dwelling unit? Does 210.18 apply?
 
craig65 said:
I
There is a small kitchen, no stove, just microwave and sink , would you (anyone) consider this a dwelling unit? Does 210.18 apply?
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Are you saying there is no kitchen in the whole building? If food is prepared in another building then I would say according to 210.12 you would not need arc faults. Seems odd but that's my read.

Same is true for 210.8 (B) . If it's not a dwelling then no need however why wouldn't you have GFCI by the sink.

Just a note in 2008 Where receptacles are installed within 6' of a sink they must be GFCI protected in non- dwellings.

You may have some bad flashlights. I would try that first.
 
Dennis Alwon said:
Are you saying there is no kitchen in the whole building? If food is prepared in another building then I would say according to 210.12 you would not need arc faults. Seems odd but that's my read.

Same is true for 210.8 (B) . If it's not a dwelling then no need however why wouldn't you have GFCI by the sink.

Just a note in 2008 Where receptacles are installed within 6' of a sink they must be GFCI protected in non- dwellings.

You may have some bad flashlights. I would try that first.
Click to expand...
there is a commercial kitchen at the back of the building that cooks all the meals for ther residents, they eat in the community dinning room.
I asked the maint. man to unplug the flash lights ... it's worth a shot
All the sinks have GFIs.
I have a meeting with them tommorow afternoon,
we'll see how it goes...................
( to be continued)
 
craig65 said:
there is a commercial kitchen at the back of the building that cooks all the meals for ther residents, they eat in the community dinning room.
I asked the maint. man to unplug the flash lights ... it's worth a shot
All the sinks have GFIs.
I have a meeting with them tommorow afternoon,
we'll see how it goes...................
( to be continued)
Click to expand...

If there is a kitchen in the building then I believe the arc faults are necessary.

Let us know what happens.
 
Reverse engineering of GFIs and AFCIs

Reverse engineering of GFIs and AFCIs

From online patent info, this IC is used in both.

http://www.national.com/ds/LM/LM1851.pdf

Page 6 of this datasheet shows one practical implementation.

But an AFCI also needs a memory to store arc signatures and a processor to compare the arc with what's in the memory. Not to mention an analog-to-digital convertor and signal conditioning stuff.

More ICs, more Internet searches. . .
 
post 24

post 24

dennis, you're probably right, but i noticed that a shared nuetral hadn't been mentioned and offered it for consideration.

p.s. those aren't my words, it's from the link i posted. it was just easier to copy and paste.
 
Dennis Alwon said:
If there is a kitchen in the building then I believe the arc faults are necessary.
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I don't see why...this building does not meet the defintion of a dwelling unit and AFCIs are only required in dwelling units.
 
don_resqcapt19 said:
I don't see why...this building does not meet the defintion of a dwelling unit and AFCIs are only required in dwelling units.
Click to expand...

So, are you saying that the permanent provisions must be in each room? I didn't read it that way. It says the rooms and suites that are provided with permanent provisions for cooking. I would take that to mean that if there is a kitchen in the building then it would require but it I can see what you are saying. I probably am misinterpreting that.

If my read were correct then all hotels would have to have arc fault since there is usually a kitchen in the building.

I tend to agree with you but I believe it should say that the cooking be provided within the room.

I guess I am thinking about a dorm room with a central kitchen where the students can cook their own meals. I would think that it would require arc fault. No???
 
found the problem... defective electrician. There was a j box behind the fridge with the neutrals were crossed. It seems these 5 rooms were wired by temp help that did not follow the as built print. :mad: :mad:
Bottom line poor foreman.. you MUST check on you help.
the result
16 hours spent on a non issue. The flash lights were not enough of a load the trip the archs right away...over time the resistors charged and triped the archs. after the first time the archs the read it as a fault and just a kept on trippin'
 
Hum,,,behind the fridge, in the kitchen,, must need AFCI's then.....:grin: :grin: :grin:
 
the hardest thing for me as a PM is trouble shooting behind the new guy. all of our "old timers" I know how they work :cool: I can go behind anyone of them and know there habits. I worked long enough in the feild with them.
the new guy :confused: :confused: :confused:
lession learned....trust no-one you dont know, they have over stated there experince. Sadly some guys that say they are electricians have not a clue what one is. :mad:
 
craig65 said:
found the problem... defective electrician. There was a j box behind the fridge with the neutrals were crossed.
Click to expand...

A JB behind the fridge on new construction. What were they thinking? Talk about the last place to look. I 'd rather take down Stickboy's wall sconce over the stair then deal with having to move a refrigerator....:grin:
 
I helped work a hotel into a dorm for college students once. We had a similar problem. We had to go threw all of the receptacle boxes, and make sure the hot's and neutrals weren't touching anywhere in the box. They couldn't be crossed at all. We pushed hots to one side, and neutrals to the other and this solved the problem. We would wire a section turn it on, and anywhere from 1 hour to overnight the breakers would trip.
 
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