Help with megger results of NM-B

[peter d]

Actually at best it would show you have no practical experience. Anyone with real world experience knows how much harder it is to pull and terminate #10 over #14.



And yes I am well aware the NEC requires #10 for most resi water heaters, so dont try that one.

Again, I will simply say your obsession with reducing ampacity to European or Canadian standards is a fool's exercise with no real benefit.

 

[kwired]

Other than AFCI's and a few grounding rules (ground rods), there isn't much that we need to change IMO.

I will add the handle tie rule for multiwire circuits and some of the identification rules for protecting those that don't really understand anyway.

Lots of other little rules that really don't bother me all that much but really are on the border of the NEC going against it's own rules of being a design manual.

 

[kwired]

Our ampacity tables. No way should anyone be running #10 to an 18 amp water heater.

Typical water heater is right about borderline of needing 12 vs 10 AWG per current ampacity tables. If the water heater wasn't required to be treated as a continuous load then 12 is acceptable - if on a 20 overcurrent device.

That said I run into many air conditioner units that have 10 AWG run to them though they could be NEC compliant with 12 AWG - even with 60C conductor, some people just don't learn what they can do and only do what they have always done.

 

[peter d]

I will add the handle tie rule for multiwire circuits and some of the identification rules for protecting those that don't really understand anyway.

Lots of other little rules that really don't bother me all that much but really are on the border of the NEC going against it's own rules of being a design manual.

I agree, I will add ballast disconnects as another.

 

[macmikeman]

Bundling rules (for dwelling romex) are insane, we all know it. At least if we are old enough to remember how we all used to drill a 2'' hole straight thru all the floor joist one end of the house to the other and run all home runs thru it, and never ever did it cause a single problem.

 

[ActionDave]

Bundling rules (for dwelling romex) are insane, we all know it. At least if we are old enough to remember how we all used to drill a 2'' hole straight thru all the floor joist one end of the house to the other and run all home runs thru it, and never ever did it cause a single problem.

That is the way I did my house.

 

[ActionDave]

I will add the handle tie rule for multiwire circuits ......

I hate that rule more than I hate any of the other rules I hate combined.

I'll add insane rules for derating wires on rooftops. I heard that may be going away in '17. If it is true that will be a good thing.

 

[don_resqcapt19]

...
Of course the above doesnt need to happen for a person to compare the NEC and ask why does BS7671 de-rate so much where we dont have to? ...

Probably because our load calculations and wire ampacities are so conservative that we don't have to de-rate as much.

 

[mbrooke]

Again, I will simply say your obsession with reducing ampacity to European or Canadian standards is a fool's exercise with no real benefit.

Can you explain why it would not be a benefit? I think you fail to grasp the theory behind it. Copper is a natural resource, and getting more expensive each day.

 

[mbrooke]

Probably because our load calculations and wire ampacities are so conservative that we don't have to de-rate as much.

I agree, however in many applications that results in over sized wire. A one size fits all often has to assume worse case scenario by default.

 

[mbrooke]

Typical water heater is right about borderline of needing 12 vs 10 AWG per current ampacity tables. If the water heater wasn't required to be treated as a continuous load then 12 is acceptable - if on a 20 overcurrent device.

That said I run into many air conditioner units that have 10 AWG run to them though they could be NEC compliant with 12 AWG - even with 60C conductor, some people just don't learn what they can do and only do what they have always done.

IMO the code should drop the continuous requirement in residential since load diversity is great enough even if a breaker or two runs at 100%, those next to them will not thus allowing heat to disperse. Even then, for some fixed load there is technically no reason to upsize the breaker along with the wire for continuous applications, up-sizing the breaker alone will suffice since no extra load can be added to the circuit (at least the CEC's reasoning).


One of the borderline code rules that gets me are 80 amp car chargers which technically can not utilize #2 NM (at least what I have read).

 

[iwire]

IMO the code should drop the continuous requirement in residential since load diversity is great enough even if a breaker or two runs at 100%, those next to them will not thus allowing heat to disperse. Even then, for some fixed load there is technically no reason to upsize the breaker along with the wire for continuous applications, up-sizing the breaker alone will suffice since no extra load can be added to the circuit (at least the CEC's reasoning).


One of the borderline code rules that gets me are 80 amp car chargers which technically can not utilize #2 NM (at least what I have read).

It's amazing that you know so much more than all those before you.

 

[mbrooke]

It's amazing that you know so much more than all those before you.

Me and the tens of thousands of people who wrote the IEC and CEC As I said, most of what I am theorizing is already being done.

 

[peter d]

Can you explain why it would not be a benefit? I think you fail to grasp the theory behind it. Copper is a natural resource, and getting more expensive each day.

I understand the theory quite well. I also understand that running #16 or #14 to a 4.5 Kw water heater is never going to fly here.

As for copper getting more expensive every day, you apparently don't buy any because the price has been dropping like a rock.

 

[peter d]

Me and the tens of thousands of people who wrote the IEC and CEC As I said, most of what I am theorizing is already being done.

Except that the CEC and IEC are irrelevant to American wiring systems and are just as subjective as the NEC in many ways.

 

[mbrooke]

I understand the theory quite well. I also understand that running #16 or #14 to a 4.5 Kw water heater is never going to fly here.

As for copper getting more expensive every day, you apparently don't buy any because the price has been dropping like a rock.

Dropping, anyone with an internet connection to Home Depot can see that, however compared to the 1980s? Copper isnt abundant either, its a natural resource.

I keep hearing from you "its never going to fly", but if if people send proposal the the CMP with detailed analysis it just might change, you never know. Someone was able convince the NEC to drop the 42 space rule, and there was proof it would not be a problem because Canada used the exact same panel guts in many cases without incident.

 

[peter d]

Dropping, anyone with an internet connection can see, however compared to the 1980s?

I keep hearing from you "its never going to fly", but if I send proposal the the CMP with detailed analysis it just might change, you never know. Someone was able convince the NEC to drop the 42 space rule, and there was proof it would not be a problem because Canada used the exact same panel gets in many cases.

You can certainly try, but rest assured, relaxing ampacity rules is completely against NEC trends right now.

But what is the practical benefit? A smaller conductor will mean more I2R losses.

 

[mbrooke]

Except that the CEC and IEC are irrelevant to American wiring systems and are just as subjective as the NEC in many ways.

Canada uses the exact same breakers, terminals, wires ect most of the time, yet both apply different rules to them. Despite that neither one is burning up. A perfect example was the 42 space rule. The exact same panel board guts that were put into a Canadian 80 space load center were also put into our 40 space load center. The only difference was a rejection feature. No fires or melt downs.

 

[mbrooke]

You can certainly try, but rest assured, relaxing ampacity rules is completely against NEC trends right now.

Which we must ask, why is our trend to increase while everyone else decreases?

But what is the practical benefit? A smaller conductor will mean more I2R losses.

Of course, thats why any electrician regardless of the code at hand should be aware of voltage drop. Even with our conservative wire you can still get excessive voltage drop under the right conditions. Benefit is less cost, material and labor.

 

[romex jockey]

Insisting American electricians:

do not pretest , That is pretty inclusive. Some do, some don't.

know how to use testers , Which testers? Do we all have to certified in each and every one?

or that it is NOT code required 110.7 states completed wiring installations "shall be free from..." It does not say how we have to arrive at that point. Visual inspection and "Trial & error" are not excluded from that process.

is just plain wrong all around

Performance testing is an NEC requirement , So is an assured EGC program, there is no 'T&A allowed' , nor would a 'bang test' be advised at high amperages unless one has unlimited funds for equipment and ER visits

The particular meter or method w/meter is not detailed in the NEC, as it's assumed a competent electrician can operate and knows the limitations of more than a mere continuity check

One can either pursue the informational notes , or google this for a world of our trade rags offerings if not.

~RJ~