What code section do you find absolutely ridiculous?

[Dennis Alwon]

What part of 240.87 do you think is silly?

Just curious as I am a member of CMP 10.

Chris

The part you wrote

Welcome back

 

[Maders]

I do not want to come off as a curmudgeon, especially as I do not post here that often.

The methods of arc energy reduction allowed in 240.87(B) are difficult to employ, costly and may not be effective if not used properly. In addition, some of these methods (especially arc-flash reduction modes) negate selective coordination when activated. This last reason bothers me the most. After all the arguing over the importance of selective coordination over the last nine years, its kind of ironic that the NEC now mandates systems that will in effect negate it.

 

[Pharon]

Selective coordination has no business being in the NEC, as it's strictly a building design issue.

Arc fault mitigation is an electrician safety issue, however, and most certainly does belong there.

 

[raider1]

The part you wrote

Welcome back

Thanks Dennis

 

[raider1]

I do not want to come off as a curmudgeon, especially as I do not post here that often.

The methods of arc energy reduction allowed in 240.87(B) are difficult to employ, costly and may not be effective if not used properly. In addition, some of these methods (especially arc-flash reduction modes) negate selective coordination when activated. This last reason bothers me the most. After all the arguing over the importance of selective coordination over the last nine years, its kind of ironic that the NEC now mandates systems that will in effect negate it.

When a breaker has the instantaneous trip function disabled for selectivity purposes it exposes personnel who work on the equipment down stream from the breaker to likely much higher levels of incident energy then if the breaker was equipped with an instantaneous trip function set at or below the available fault current. When this condition exists it becomes necessary to employ other methods to reduce the arc energy that could result in the case of an accident.

As far as selective coordination is concerned, the NEC only mandates selective coordination in a few select incidences (See 700.28, 701.27 and 620.62) the levels and necessity for selective coordination is usually left up to the design professional and the building owner.

Chris

 

[raider1]

Selective coordination has no business being in the NEC, as it's strictly a building design issue.

Arc fault mitigation is an electrician safety issue, however, and most certainly does belong there.

Selective coordination does have a place in the NEC when cascading of overcurrent devices would affect life safety features such as emergency lighting, accessible means of egress elevators, smoke control systems etc...

Chris

 

[Pharon]

Selective coordination does have a place in the NEC when cascading of overcurrent devices would affect life safety features such as emergency lighting, accessible means of egress elevators, smoke control systems etc...

Chris

I disagree. The purpose of the NEC is to provide direction to minimize the risk of electrical shock and fires/explosions centered around installation and maintenance. The scope of preventing OCPD cascades in emergency systems should fall to NFPA 110 (or NFPA 99 for hospitals, etc.).

 

[Maders]

When a breaker has the instantaneous trip function disabled for selectivity purposes it exposes personnel who work on the equipment down stream from the breaker to likely much higher levels of incident energy then if the breaker was equipped with an instantaneous trip function set at or below the available fault current.

Agreed. However there is no way to actually mandate that an operator activates a 'maintenance-mode' before working on live equipment.

When this condition exists it becomes necessary to employ other methods to reduce the arc energy that could result in the case of an accident.

As far as selective coordination is concerned, the NEC only mandates selective coordination in a few select incidences (See 700.28, 701.27 and 620.62) the levels and necessity for selective coordination is usually left up to the design professional and the building owner.

708.54 also. These few select instances are mostly concerned with life safety systems (e.g. all the more reason to mandate full selectivity all of the time)

IMHO, allowing operators to choose between a) low arc-energy and low-selectivity or b) higher arc-faults and selectivity introduces a high probability of improper operation. Don't get me wrong, I am a proponent for the highest level of worker safety, but IMHO there are better ways to achieve this other than mandating complex systems that are difficult to implement and will most likely be misunderstood and misused by the very operators that they are intended to protect.

 

[480sparky]

I disagree. The purpose of the NEC is to provide direction to minimize the risk of electrical shock and fires/explosions centered around installation and maintenance. The scope of preventing OCPD cascades in emergency systems should fall to NFPA 110 (or NFPA 99 for hospitals, etc.).

The NFPA doesn't back you up on this, IMHO.

90.1 Purpose.
(A) Practical Safeguarding. The purpose of this Code is the practical safeguarding of persons and property from hazards arising from the use of electricity.

 

[Pharon]

The NFPA doesn't back you up on this, IMHO.

Actually, it does. This is language in the NEC 2014 Handbook, from the NEC Committee itself:

The scope of the National Electrical Code Committee is as follows:

This committee shall have primary responsibility for documents on minimizing the risk of electricity as a source of electric shock and as a potential ignition source of fires and explosions. It shall also be responsible for text to minimize the propagation of fire and explosions due to electrical installations.

And that's the way it should be. Once the NEC Committees start implementing design concepts, all they're gonna do is start contradicting all the other Codes. Selective coordination, lit-faced receptacles in nursing homes... really? Stick to what you do best -- safety and prevention of electrical hazards for trained personnel.

 

[raider1]

Agreed. However there is no way to actually mandate that an operator activates a 'maintenance-mode' before working on live equipment.

Correct, just as there is no way the NEC can mandate that someone use the required local disconnect for a motor, but that does not mean that the NEC should not address disconnecting means. OSHA and NFPA 70E addresses working on or near live parts.

IMHO, allowing operators to choose between a) low arc-energy and low-selectivity or b) higher arc-faults and selectivity introduces a high probability of improper operation. Don't get me wrong, I am a proponent for the highest level of worker safety, but IMHO there are better ways to achieve this other than mandating complex systems that are difficult to implement and will most likely be misunderstood and misused by the very operators that they are intended to protect.

240.87 is intended to provide means to reduce arc energy when the instantaneous trip function of a circuit breaker is disabled for selectivity purposes. For situations where the instantaneous trip functions are enabled 240.87 does not apply.

240.87(B)(3) Energy-reducing maintenance switching allows maintenance personnel to engage an instantaneous trip function during the time that the personnel are working on the system while energized.

Chris

 

[raider1]

Actually, it does. This is language in the NEC 2014 Handbook, from the NEC Committee itself:


And that's the way it should be. Once the NEC Committees start implementing design concepts, all they're gonna do is start contradicting all the other Codes. Selective coordination, lit-faced receptacles in nursing homes... really? Stick to what you do best -- safety and prevention of electrical hazards for trained personnel.

Many jurisdictions do not adopt NFPA 110 or 99 and are not under any obligation to follow the requirements found in those documents.

Also many of the members of those committees (99 and 110) are members of the NEC committees. I know people who sit on both NFPA 99 committees and are members of NEC CMP 15.

Coordination between NFPA committee's is very important.

Chris

 

[Pharon]

So NFPA is supposed to create needless and mindless inconsistencies because some jurisdictions are too lazy to adopt multiple codes and standards? Not to mention that just because Hickville, USA doesn't recognize NFPA 99 doesn't mean that the hospital there isn't mandated to follow those standards in order to get Joint Commission and CDC accreditation for Medicare funding.

According to NFPA, the NEC has a specific purpose and function. And it would be nice to see the various NEC committees take that directive into consideration before dabbling in areas they have no business being involved with in the first place. Because all it does is create a domino effect of headaches for other code committees, consulting engineers, and all the way down to the end users.

 

[raider1]

So NFPA is supposed to create needless and mindless inconsistencies because some jurisdictions are too lazy to adopt multiple codes and standards? Not to mention that just because Hickville, USA doesn't recognize NFPA 99 doesn't mean that the hospital there isn't mandated to follow those standards in order to get Joint Commission and CDC accreditation for Medicare funding.

According to NFPA, the NEC has a specific purpose and function. And it would be nice to see the various NEC committees take that directive into consideration before dabbling in areas they have no business being involved with in the first place. Because all it does is create a domino effect of headaches for other code committees, consulting engineers, and all the way down to the end users.

I don't see where NFPA is creating needless and mindless inconsistencies because the NEC addresses selective coordination for specific life safety electrical circuits.

90.1 Purpose.
(A) Practical Safeguarding. The purpose of this Code is
the practical safeguarding of persons and property from
hazards arising from the use of electricity. This Code is not
intended as a design specification or an instruction manual
for untrained persons.

Does there not arise a hazard if there is a cascading of overcurrent devices that protect life safety systems?

Chris

 

[Maders]

Correct, just as there is no way the NEC can mandate that someone use the required local disconnect for a motor, but that does not mean that the NEC should not address disconnecting means. OSHA and NFPA 70E addresses working on or near live parts.

It may be splitting hairs, but a local disconnect switch which de-energizes a piece of equipment and clearly makes it safe is a whole lot different than a maintenance mode switch on the trip unit of a circuit breaker. The function of the latter will not necessarily be apparent or understood by even by a qualified operator.

240.87 is intended to provide means to reduce arc energy when the instantaneous trip function of a circuit breaker is disabled for selectivity purposes. For situations where the instantaneous trip functions are enabled 240.87 does not apply.

I am not sure that is the case. The way I read the new requirements, 240.87 requires arc-energy mitigation on all circuit breakers 1200A and larger, regardless of instantaneous trip functionality or arc-flash hazard.

"Where the highest continuous current trip setting for which the
actual overcurrent device installed in a circuit breaker is rated
or can be adjusted is 1200 A or higher, 240.87(A) and (B) shall
apply."

Am I missing something?

 

[Maders]

Does there not arise a hazard if there is a cascading of overcurrent devices that protect life safety systems?

The NFPA standards council has ruled (on at least two occasions that I can recall) that selective coordination is not an installation requirement and not under the purview of the NEC. I will forward the links to the SC decisions if I can find them.

 

[kwired]

I disagree. The purpose of the NEC is to provide direction to minimize the risk of electrical shock and fires/explosions centered around installation and maintenance. The scope of preventing OCPD cascades in emergency systems should fall to NFPA 110 (or NFPA 99 for hospitals, etc.).

Actually, it does. This is language in the NEC 2014 Handbook, from the NEC Committee itself:


And that's the way it should be. Once the NEC Committees start implementing design concepts, all they're gonna do is start contradicting all the other Codes. Selective coordination, lit-faced receptacles in nursing homes... really? Stick to what you do best -- safety and prevention of electrical hazards for trained personnel.

I can see where you are coming from, I also see NFPA trying to make requirements of one of their codes comply with the requirements of other applicable codes to some degree.

If NEC only purpose is to minimize shock fires/explosions I think the thickness of the book could dramatically be reduced especially if the purpose is only for protecting installers and maintenance people. What does determining minimum conductor size (doesn't matter if a service, feeder, branch circuit..) have much to do with the safety of an installer or maintenance person, it is more likely to be a hazard to the end user if not done correctly, or not to follow minimum receptacle placement requirements in a dwelling? Much of the content is for the end user and not so much for the maintenance man - 70E is for the protection of the maintenance man.

 

[augie47]

240.87 (2014)
700.8 (2014)
700.10(B)

517.41(E) (2014)*

* - This one takes the prize.

You don't suppose the manufacturers had any input on this one do you ?
Betcha those illuminated receptacles have a decent price tag.

 

[kbsparky]

I find it's absurd to prohibit undercabinet lighting to be connected to SABCs. It's perfectly acceptable to PLUG THEM INTO an outlet, but if I want to permanently wire one up, I need a different circuit??

This is a design issue, and not a safety one. The Code has no business in setting design standards as they expressly state in the beginning of the text, but then they get into the designs anyways?

As well as requiring a neutral conductor in every switch box regardless of whether your switch needs one or not. Again, this is a design issue.

Some of the others already mentioned in this thread, like being unable to mark wires smaller than #6 with white tape (while marking `em GREEN is fine), or being anal about those 2-wire switch loops, etc.

 

[kbsparky]

Here's another one that takes the cake:

IF I have a branch circuit with #6 conductors on a 60 Amp breaker, then I need a #10 EGC.

Take that same circuit, but put it on a 20 Amp breaker, and now I need a #6 EGC??!?

Totally insane!!