First... We KILL all the LAWYERS.

You're next at bat.

 

But this isn't about lawyers though. I'm wondering if the courts, or even legislatures, have made an official ruling clarifying this exact situation.

 

I'm asking about the exact intent (for clarity purposes when the NEC's wording is unclear or contradictory) of the NEC by its creator (NFPA) or buildings department, and I thought there would be some people here that are part of those administrative boards. So, that is why I asked. If it is only electricians who are not part of permit-approving boards here, then of course it is pointless to ask here. However, one first needs to try on order to know. That is why I'm posting here to see if I can try to get any insider information from the authors of the NEC and electrical permit issuers.

So, is it normally only electricians here, or are there also a substantial amount of posts from NFPA staff and electrical permit issuers here?

 

I presume

So, is it normally only electricians here, or are there also a substantial amount of posts from NFPA staff and electrical permit issuers here?

The NFPA Staff are forbidden, as a condition of their employment, from commenting on Code interpretations with the exception of particular staff that work with the particular Code Making Panel (CMP) responsible for the particular part of the code which gives rise to the particular issue. There practice is to answer questions which are specific to the application of that particular paragraph to electrical work and what they provide, to NFPA Members only I believe, is an informal interpretation. You have to agree in advance of receiving the answer that it is not the position of the NFPA or the CMP for that article. No agreement no answer.

To get a Formal Interpretation you must file the inquiry in the proper form worded so that it can be answered Yes or No. Yes or No is all you get as a result. Expecting someone from the NFPA to comment about possible liability for the publishing of one of their Standards is a waste of time. It would be referred to their in house or retained attorney who would mark it "No reply" All you might get is a boiler plate response something like "It is not the policy of the NFPA to comment on any hypothetical question nor to provide legal advice on any matter. You will have to consult an attorney." Certainly you wouldn't expect them to say "Don't worry about it. If anything goes wrong it is all our fault." Why not hang a banner on the front wall of there building reading "Sue Us. Our treasury is at your disposal."

If the situation you postulate was leading to the outcome you are concerned about the whole electrical industry would know about it by now. The diversity of use principal, on which the section I think you are referring to is based, has been in use for decades. There is no ongoing pattern of fires caused by allowing the reduction of Service and Feeder conductor size for dwellings. Remember that the adopting Authority Having Jurisdiction (AHJ) had to adopt it for it to be enforced involuntarily as law. That step is a pretty good shield between the NFPA and any civil action based on an alleged error in the Code's requirements. You cannot sue a State or one of it's political parts without the States permission. That is based on the principal of Sovereign Immunity. Since the government functions in place of a Sovereign and the Sovereign is the source of the law it is a legal absurdity to attempt to bring a civil suit against her/him.

I am definitely not a lawyer nor do I play one on late night municipal television. What I have opined is based on municipal management training I received 40 years ago. It is worth exactly what you have paid for it! I'd suggest that you go to a law school legal clinic were students approaching graduation answer legal questions put to them under the supervision of their professors. Keep in mind that you don't pay them for their Freely given opinion from a person that you already know is not qualified as an attorney. I'd suggest that you call ahead because they may be just as allergic to hypotheticals as most other legal practitioners are.

Tom Horne

 

This allowance is only for dwellings. Just by their very nature, they have smaller supplies. Plus your talking overloads on multiple breakers when having a catastrophic failure. You’re now going to have faults phase to phase or phase to ground. Those aren’t going to wait for a trip curve.

 

Just by their very nature, they have smaller supplies. Plus your talking overloads on multiple breakers when having a catastrophic failure. You’re now going to have faults phase to phase or phase to ground. Those aren’t going to wait for a trip curve.

Not necessarily. It can just be normal types of loads, just at a hugely abnormal amount of load. This is why I said rare. Such a specific type of overload may be so rare that it has never happened, not even once, in all of the 125+ years of the National Electric Code. I'm just wondering who will be liable if (not necessarily when, because it might take 1,000 years for one to finally happen, and the NEC would likely not exist by then) such an event happens due entirely by fault of the coverage hole in the code.

 

As an electrical contractor, I carry insurance. It’s more because of lawyers than my workmanship.

 

Everyone meets Code, which is theoretically a consensus safety opinion by industry experts. Even if you sue NGPA itself you hav to show that somehow the code making process is defective. This would be easier to show with AFCIs but not 331.

Among other issues you’d hav to show actual damages to change the Code or claim liability or there is no tort. So from a legal point of view this is all a nonstarter.

Plus your technical argument does not hold water. The handle ratjng is the “pickup” rating. The breaker should never trip under any temperature or X/R below that rating in open air. In a panel it decreases to 80% of that value owing to elevated temperatures in a panel unless it is 100% duty rated. The breaker curve should be compared to a damage curve for the wiring that you are protecting. If it is below that curve (including tolerance) out to 3 hours, we are good. We do not consider or use “infinite” conditions. The handle value is a “size”..

As to arguing about diversity factors if you have a “typical” load it won’t go above this. I challenge you to find a non-contrived case where it does. If you are doing commercial/industrial work you can’t go by recommended diversity. If I have a process where I know I have 3 motors that have to run at all times and the controls tweak a valve to control amps, diversity goes out the window. Similarly when designing for motor loads (article 430 or 440) I really don’t care what the handle value is because a circuit breaker nominal value is grossly oversized: I’m just sizing for short circuits.

This myth that NEC does not provide adequate protection is simply not true. This has been around for a while.

 

We are suppose to size the feeders for the calculated load. Yes someone could start to overload the circuits in the house and eventually it could affect the feeders. But it is the homeowner violating the rules. They could convert the bedrooms into rental rooms with hot plates or start a grow room with high intensity lights. We could use 3/0 and a 200 amp service but then they could keep adding loads. Circuit breakers work on heat and they probably will trip before it causes bigger problems. If it keeps tripping and the homeowner keeps re-setting it, then that is on him.
I kind of agree on allowing a de-rating on the service feeder and a lot of towns also question some things. #4 for a 100 amp service with gas cooking and dryer is fine. But with an electric dryer and electric stove I use #2 copper.

 

But it is the homeowner violating the rules.

Here, I am assuming that the homeowner is not violating the rules. For example, electrical codes prohibit people from installing wiring that does not have sufficient ampacities for the expected loads or hard-wiring devices that have loads exceeding the ampacity of the supply circuit. However, it does not prohibit people from plugging into existing receptacle outlets for multiple appliances collectively have a current draw that exceeds the ampacity of the supply. In the last case, it is only the job of the circuit breaker to prevent overload.

For example, a house may have a main breaker rated at 100A and 10 individual breakers that have a combined rating of 150A, but the service conductor is only rated for 83A. In a large party, many people may decide to bring their own countertop appliances and plug into multiple outlets throughout the home to prepare for food. Each circuit is loaded to 13A, which is well within the limit, so none of their breakers trip. However, the main breaker and service conductor now each have a load of 130A, which is above theor ratings. Given that breakers trip within 115% to 145% of their ratings for long-duration loads, that breaker if manufactured peroperly doesn't have to trip at 130A. That main breaker happens to be one that is less sensitive but still passes quality control, so it doesn't trip despite not being defective. Now, the service conductor is at 156.6% of its rated load and causes a fire from being overloaded. Now who is liable?

 

These are not even realistic scenarios. I have never been to a party where people bring their own appliances. That is just trolling imo. Also a breaker will trip over the ampacity of the breaker but it may take a few minutes or so which is not enough time to cause damage to the conductor.

 

People might not bring their own appliances to a party but there are a lot of foreigners in my area that buy houses and rent out bedrooms complete with a hot plate and small refrigerator. I am doing a fire job right now where the lady had a ranch house split into 4 illegal apartments. She wants it restored the way it was before the fire but she is not going to rent it out. Right. Is there an emoji for me being sarcastic?

 

How much electrical energy do typical crackheads use when they are cooking up nasal decongestants ?

 

I have a neighbor who has these really bright purple-ish color lights on all night in one of the bedrooms. I wonder what it is for. ?

 

NEC 2017 edition NFPA ART: 310.15 (7) (1) feeders can be no less than 83% it does not say SHALL, they must be large enough to carry the calculated demand.
For new home construction it would be wise to provide for future loads.

 

NEC 2017 edition NFPA ART: 310.15 (7) (1) feeders can be no less than 83% it does not say SHALL, they must be large enough to carry the calculated demand.
For new home construction it would be wise to provide for future loads.

six months ago they might have cared

 

A conductor's rated ampacity is not the ampacity at which it "melts". You can put at least twice the rated amps on a conductor before it "melts".It may got hot and the plastic insulation may get a bit crispy over time but sustaining 150% of rating should be no problem for brief intervals

Current Carrying Capacity of Copper Conductors

Current Carrying Capacity of Copper Conductors

www.multicable.com

#12 good for 40 amps lol - or more!

 

A conductor's rated ampacity is not the ampacity at which it "melts". You can put at least twice the rated amps on a conductor before it "melts." It may got hot and the plastic insulation may get a bit crispy over time but sustaining 150% of rating should be no problem for brief intervals

Current Carrying Capacity of Copper Conductors

Current Carrying Capacity of Copper Conductors

www.multicable.com

#12 good for 40 amps lol - or more!

I was the Station House manager for my volunteer fire department. The City's Recreation Department was a tenant in the basement which was used as a basketball court. The Court was lighted by Mercury Vapor lights. Each required 4 amps and there were 4 of them in 3 rows with one 20 ampere, Number 12 American Wire Gauge (12AWG) for each of the 3 rows. The circuits were run in Electric Metallic Tubing from a feeder supplied panel located on the wall of a balcony only 30 feet to the first row. The Service to the building was 208/120 volts 3Ø so this particular load was an exemplary load for a 3Ø multiwire branch circuit. That is exactly how it was run. A to the 1st row, B to the 2nd row, C to the 3rd row, and an actual neutral observed in it's natural habitat. 16 amperes per phase or exactly 80% of each 20 ampere circuit.

Then the recreation department decided they needed a heater in their office at court level. Because of internal politics the City hired a real trunk slammer to install the required circuit and heater. Not having 2 adjacent breaker positions in the panel the trunk slammer, who was to an electrician what a seahorse is to a racing thoroughbred horse, rearranged the breakers to get the needed adjacent spaces in the panel to supply the heater through a 208 circuit. The trunk slammer cleverly managed to get all 3 of the 20 ampere lighting breakers onto the same phase busbar. 16 * 3 = 48 amps on that Grounded Current Carrying Conductor (GCCC), which is called a Grounded Conductor for purposes of discussion. All of the wire used for the lighting circuits, which were installed by an actual licensed electrical contractor, was THHN. THHN has an ampacity of 30 amperes at 90° Centigrade. There were only 3 conductors in the EMT for the purpose of derating because the neutral of a balanced 3Ø circuit is not counted for the number of conductors in a conduit for derating purposes. OK that is 160% rather than 150% of THHN's table ampacity. That neutral failed in seconds. I think the premise of of 150% for brief intervals is totally erroneous.

Tom Horne