Provisional Neutral

Status
Not open for further replies.
R

Rock86

Senior Member
Location
new york
Occupation
Electrical Engineer / Electrician
I know its somewhere....

Does anyone know where is talks about a provisional neutral in 2017 NEC? I'm trying to remember if it was only certain equipment or if it was to bring a neutral down with a switch leg.
 
Are you asking about 404.2(C)?.
The word "provisional" does not appear in any edition of the NEC from 1999 through 2017.
 
don_resqcapt19 said:
Are you asking about 404.2(C)?.
The word "provisional" does not appear in any edition of the NEC from 1999 through 2017.
Click to expand...
hmmm... that might be what I had read before. It don't think that is what I was thinking about though. I could thought there was a change from either 2008 to 2014, or 2014 to 2017 that required a grounded conductor to be ran for future use in applications where a neutral was not called for. Like an AC unit which only needs 240V. You would leave the grounded conductor capped and secured in place. I know it sounds like a crazy idea...
 
Not a crazy idea, its a good rule to prevent shocks. Motion detectors got 120v from hot to ground, about 5 ma per detector, on the EGC. Do you see the issue with multiple detectors?
 
hillbilly1 said:
The code is basically written by manufacturers, so how do you sell more motion sensors when at the time, most did not have a neutral present?
Click to expand...
They were selling plenty of occupancies without the neutral rule...the product standard permitted them to use the EGC as the neutral for the electronics. UL was not willing to change the product standard unless the NEC was changed to require a neutral at potential electronic switch locations.
 
don_resqcapt19 said:
They were selling plenty of occupancies without the neutral rule...the product standard permitted them to use the EGC as the neutral for the electronics. UL was not willing to change the product standard unless the NEC was changed to require a neutral at potential electronic switch locations.
Click to expand...
That’s because they got the product standard passed previously, the neutral rule was not pushed by them, because they already had what they wanted.
 
In my view the idea of letting the manufacturers use the EGC for the electronics was a terrible idea. The code finely addressed this in the 2017 edition with the new paragraph at the end of 404.2(C). I don't see how it will ever be enforced given the exception that follows.
 
texie said:
In my view the idea of letting the manufacturers use the EGC for the electronics was a terrible idea. The code finely addressed this in the 2017 edition with the new paragraph at the end of 404.2(C). I don't see how it will ever be enforced given the exception that follows.
Click to expand...
I agree that it was a bad idea, and that the problem would have been resolved much quicker if AHJs would have red tagged the installations of the devices that used the EGC as a current carrying conductor, but that is more difficult than it sounds as there really is no specific rule in the NEC to cite as the violation.

After the switch box neutral rule went into the code, the product standards were change to prohibit these devices from using the EGC as a current carrying conductor. The 1/1/2020 effective date was to give UL time to rework the standard and for the manufactures to modify their products, which in some cases only required them to replace a green tail with a white one.
 
Yep and they made the sensors with a bonding strap that you removed if you had a grounded conductor available to use.
 
Status
Not open for further replies.
Top