NEC Changes For #14 Ampacity

Status
Not open for further replies.
mbrooke said:
I am not snipping (at least not my intention), just defending my points.

Anyway, going back to FionaZappa. What are R values would be sufficient for #14, 12 and 10 to meet the 15 amp requirement plus 134% for overloads?
Click to expand...

i dont understand your question. R values that would allow the wire to stay below 60C for the existing ampacity of each wire size ??
 
mbrooke said:
Ok, that is a good start. :thumbsup: But what about a 3va per foot lighting/outlet circuit?
Click to expand...

No, I wasted too much time on my AC unit example..

If you want to see that one you have to do it.

You post your thoughts on lengths and circuit routing as this is your claim that is in dispute.
 
iwire said:
No, I wasted too much time on my AC unit example..

If you want to see that one you have to do it.

You post your thoughts on lengths and circuit routing as this is your claim that is in dispute.
Click to expand...



That is correct, but picture what happens when I start wrapping that wire around the walls in various rooms to cover outlets, then up to a hall light, then switch leg and then a 3 way traveler down to the stair landing. 100 feet here is not out of the question.
 
mbrooke said:
That is correct, but picture what happens when I start wrapping that wire around the walls in various rooms to cover outlets, then up to a hall light, then switch leg and then a 3 way traveler down to the stair landing. 100 feet here is not out of the question.
Click to expand...

Then you went beyond the 'homerun' electricians know this. :p
 
iwire said:
Then you went beyond the 'homerun' electricians know this. :p
Click to expand...

Thats why I said "furthest point in a circuit"

Ok maybe my terminology is off (everyone knows I suck at English) but in my mind I have a rough idea of the distance between the breaker and furthest point.
 
iwire said:
Yes it was.




I am well aware that you think you know this.

In respect of Jim Ds comment that is as far as I will take that. :)
Click to expand...



Reality is, take what yon know about wiring then apply short circuit calcs. Mag trip is hit or miss, especially with older breakers. I still stand behind my rough estimate of 1/3 to 2/3. An EFLI meter will prove me near correct.
 
mbrooke said:
Well where do I begin... any question you have that is specific?

I do know for some odd reason in the 90s they started lowering the mag trip values on single pole 15 and 20amp breakers. No solid reason is stated, however values started going down from 20x, 32x, 35x and no mag trip down to about 12x. Interestingly well before that Square D had breakers with a low 8-10x value, which I would guess is the brand "D" noted in the UL reports.
Click to expand...

Apologies for being less than specific Mr MBrooke, as i was trying to address the broader prospective.

My first Q is the realization that the OCPD manufactures focused much on magnetic trip levels in about the time frame you stated. Inasmuch as this crew may not think it relevant, THEY did.

Why if UL requires no listing of it....?

Secondly, {and i say this in all humility}, just what differs magnetic EMF levels from current flow?

~RJ~
 
mbrooke said:
Reality is, take what yon know about wiring then apply short circuit calcs. Mag trip is hit or miss, especially with older breakers. I still stand behind my rough estimate of 1/3 to 2/3. An EFLI meter will prove me near correct.
Click to expand...

You are free to remain wrong here. :D
 
By the way a couple of times you claimed I was assuming infinate bus.

I am not, that suggests I did calculations which I did not. I have never done a fault current calculation. Like most electrians I have never had a reason too.

I am just going by real life experiences.
 
iwire said:
By the way a couple of times you claimed I was assuming infinate bus.

I am not, that suggests I did calculations which I did not. I have never done a fault current calculation. Like most electrians I have never had a reason too.

I am just going by real life experiences.
Click to expand...

Huh? :blink: I was the one that claimed infinite buss because its easier to understand. That is what I used in my original example. In reality factoring the transformer and drop would produce lower numbers, but the outcome still proves my point that after a certain amount of feet the natural conductor impedance drops current below the magnetic trip level.
 
romex jockey said:
Apologies for being less than specific Mr MBrooke, as i was trying to address the broader prospective.
Click to expand...

Its ok apologies accepted, and dont worry. If anything I owe you an apology. :)

My first Q is the realization that the OCPD manufactures focused much on magnetic trip levels in about the time frame you stated. Inasmuch as this crew may not think it relevant, THEY did.
Click to expand...
You are 100% correct, however to this day I have a hard time understanding why. The closest evidence I can find is this:

http://paceforensic.com/pdfs/Circuit_Breakers_The_Myth_of_Safety.pdf


What ever it was it was enough to get manufactuers to change without CMP or UL mandates. Whether they were escaping liability, made a discovering in its best interest or just arbitrary reason is unknown.


Why if UL requires no listing of it....?
Click to expand...

No idea, however that is something I always wonder about. If UL does not require a magnetic trip, why is it even added to breakers in the first place when in theory its removal can save cost? Perhaps the question is, are the UL standards outdated?

Secondly, {and i say this in all humility}, just what differs magnetic EMF levels from current flow?

~RJ~
Click to expand...

If you mean magnetic field nothing. The more current flow the higher the magnetic field. One area I do believe magnetic trip comes in handy is during high current short circuits where the magnetic forces do great stress. Here is a visual:


Starting at 2:15:

https://www.youtube.com/watch?v=3dckmSgp1nw
 
Time to update that slide rule

Time to update that slide rule

iwire said:
By the way a couple of times you claimed I was assuming infinate bus.

I am not, that suggests I did calculations which I did not. I have never done a fault current calculation. Like most electrians I have never had a reason too.

I am just going by real life experiences.
Click to expand...

My 'real life electrical' experiences have traditionally addressed 110.24

Usually a poco EE informs me of impedance @ the Xformer lugs, to which i meet CODE requirements providing service equipment meeting or exceeding values , as well as proving it to my AHJ.

How would i spec equipment otherwise?

Further, the introduction of larger motors alters this as well. Most (at least my area) poco's dictating 10hp and up a starter benchmark

How do they know?........those S-meters go into demand mode .....

Reading the '17 rop's, it would appear more calcs are on the cmp radar


~RJ~
 
You are 100% correct, however to this day I have a hard time understanding why. The closest evidence I can find is this:

http://paceforensic.com/pdfs/Circuit_Breakers_The_Myth_of_Safety.pdf
Click to expand...


Fredrick Franklin is a trade rag writer, who name also appears @ the patent office ....article
What ever it was it was enough to get manufactuers to change without CMP or UL mandates. Whether they were escaping liability, made a discovering in its best interest or just arbitrary reason is unknown.



No idea, however that is something I always wonder about. If UL does not require a magnetic trip, why is it even added to breakers in the first place when in theory its removal can save cost? Perhaps the question is, are the UL standards outdated?
Click to expand...

I'll wager more to the story exists Mr MBrooke....


If you mean magnetic field nothing. The more current flow the higher the magnetic field. One area I do believe magnetic trip comes in handy is during high current short circuits where the magnetic forces do great stress. Here is a visual:


Starting at 2:15:

https://www.youtube.com/watch?v=3dckmSgp1nw
Click to expand...
[/quote]

very thorough testing(s) there....

~RJ~
 
Last edited:
romex jockey said:
Fredrick Franklin is a trade rag writer, who name also appears @ the patent office ....article





~RJ~
Click to expand...


And we have this:

http://paceforensic.com/videos


A few things I notice:

1. Sparking from short circuits is re-labelled "arcing"

2. In each test destructive instigation is used to prove a point. Such conditions do not reflect the real world (like the already burning cardboard on fire melting the cord) or show how those claimed conditions propagate to fire.


Anyway about first the article. The author makes a stretch an arcing service drop causes high voltage transients and how AFCIs would save the home, but if thousand volt spikes are coming from the POCO I doubt AFCIs will do much.
 
Status
Not open for further replies.
Top