2017 NEC where a residential AFCI is not required

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JFletcher said:
Adam, while I agree with your post, it would be much simpler to mandate insulated staples that cannot be over driven. The average residential job, that might amount to $3 more material cost.

As to the original posters number one point, how can smoke alarms not be on an afci circuit when they are required in bedrooms, and those are all outlets? What is the specific exemption in the 2017 code that says smoke alarm circuits either don't have to be or cannot be afci protected?
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We only use insulated staples here in New England. Uninsulated ones seem primitive to me.
 
My biggest question is... does the staple need to be driven hard or is it just there to keep the wire close to the wood soo it is not flopping around in the space and liable to be almost anyplace in the wall?Could we be overdriving because we are trying to make it not move at all when all we really need to do is regulate where it is in regards to the studs so it has less chance of being damaged?
I mean, I understand the requirement about not forcing it into sharp bends... that makes sense, but, if I can let my wires flop around in my conduit, why does the same wire, when in NM cables, need locked down to zero movement in a way that makes it so easy for us to damage when installing? Why cant we install it so it could still be pulled a bit under the staple?
 
peter d said:
That's the dumbest and worst idea ever. I hate needless complexity. That's a solution looking for a problem.
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And so are AFCI to a certain extent.

Adamjamma said:
not sure about that one myself but... didnt I read in the same code that the fire alarm stuff now has to be gfci'd???

Personally, I am not sure why the difference between USA andEurope on the GFCI RCD stuff... 240 volts in Europe yet most residential is only 30ma..not the 5 of the USA... and the RCD covers 5 or 6 breakers at one time... Means more splits of the panel... but less cost for RCD.
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GFCI (5 mA) is for people protection. Higher trip thresholds are for equipment protection. Unless the fire alarm is supplied via a receptacle GFCI, shouldn't even be considered as a requirement at all IMO.

Adamjamma said:
My biggest question is... does the staple need to be driven hard or is it just there to keep the wire close to the wood soo it is not flopping around in the space and liable to be almost anyplace in the wall?Could we be overdriving because we are trying to make it not move at all when all we really need to do is regulate where it is in regards to the studs so it has less chance of being damaged?
I mean, I understand the requirement about not forcing it into sharp bends... that makes sense, but, if I can let my wires flop around in my conduit, why does the same wire, when in NM cables, need locked down to zero movement in a way that makes it so easy for us to damage when installing? Why cant we install it so it could still be pulled a bit under the staple?
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With soft wood used in some new construction it is easy to drive even plastic staples in too hard sometimes, this is an installer issue that just plain doesn't care and not something needing to be fixed with an AFCI.

One doesn't need a 20 oz hammer and take full swing to install these staples.:roll:
 
Well, I often wonder if the threshold is wrong in the USA? I mean, the threshold is 30 ma in Europe but for whole dwelling now including lights... based upon danger of switching a damaged lightbulb... so is quoted as a personal requirement not equipment requirement... and. At 240 V... is something like 7 watts... if I recall...while the tighter requirement of the USA is like half a watt...at 240 the 5 ma would be like 1 watt plus...

but would either one hurt you before tripping the breaker? Which one would have more nuisance trips?

Perhaps that is one reason why the USA has to protect every single circuit yet the UK and Europe protect around 5 circuits with each RCD...
 
Adamjamma said:
My biggest question is... does the staple need to be driven hard or is it just there to keep the wire close to the wood soo it is not flopping around in the space and liable to be almost anyplace in the wall?Could we be overdriving because we are trying to make it not move at all when all we really need to do is regulate where it is in regards to the studs so it has less chance of being damaged?
I mean, I understand the requirement about not forcing it into sharp bends... that makes sense, but, if I can let my wires flop around in my conduit, why does the same wire, when in NM cables, need locked down to zero movement in a way that makes it so easy for us to damage when installing? Why cant we install it so it could still be pulled a bit under the staple?
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the staple is really there just to center of the wire in the middle of the stud cavity so that it is not flopping around when the drywallers come. They are obviously not required in remodels because you are allowed to fish in non metallic cable.

Every single run of Romex I have ever seen running across the joists in the attic, none of that wire is ever stapled down.

they should be snug so the wire doesn't just slip through, but not so much that they even deform the jacket. If you've ever used a nail on cable stacker, you know that they just hold the wires there gently.

I still have a staple gun that shoots insulated non-metallic staples, but I think they went out of business some years ago. Would have been pretty sweet if it was designed better, if the clip of staples got bent in the slightest it would misfire horribly and jam up... Even under the best of circumstances it was more trouble than it was worth.

I agree with Peter D in that afci Breakers to fix over driven staples is like addressing the symptom rather than curing the problem. It's not brain surgery, it's a half a cent staple. put wire underneath, beat with heavy object... Just not too hard. So easy a caveman could do it.
 
Adamjamma said:
Well, I often wonder if the threshold is wrong in the USA? I mean, the threshold is 30 ma in Europe but for whole dwelling now including lights... based upon danger of switching a damaged lightbulb... so is quoted as a personal requirement not equipment requirement... and. At 240 V... is something like 7 watts... if I recall...while the tighter requirement of the USA is like half a watt...at 240 the 5 ma would be like 1 watt plus...

but would either one hurt you before tripping the breaker? Which one would have more nuisance trips?

Perhaps that is one reason why the USA has to protect every single circuit yet the UK and Europe protect around 5 circuits with each RCD...
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30 mA trip will still significantly reduce risk of shock. Majority of trips for either 5 or 30 mA occur before a person becomes part of the circuit is the main reason why.

I believe the main target at first with GFCI was swimming pools, 5 mA of current is a problem in that sort of environment. Next few places where GFCI was required also had more direct involvement of water being present. 5 mA is definitely enough to give a person a good shock, and is possible to kill people if it travels directly through the heart from what I understand. You don't want to be in an open EGC path when pressing test button on one of those plug in GFCI testers, it will trip the GFCI, but it will also hit you good if you are in the return path.
 
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