Does 620.62 apply to my elevators

Status
Not open for further replies.
I am doing a five story hotel with two elevator cars in Lakeland, FL. I ran into a situation where the Electrical Inspector is calling for a selective coordination for ground fault. This is not our first hotel with 2 cars and have never ran across this situation. I have a 2000 amp service with 2-175 amp breakers that feeds each car. I interpret the code as one feeder breaker feeding two cars via tap rule. I would like to hear from Mike and others to clue me in.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
I agree with you, except with regard to your example of applying the tap rule. If you had one circuit breaker on your main board, and if it fed two elevators, and if the conductors went from the main board to one disconnect's line side with double lugs being used to run conductors to the other disconnect, AND IF all the conductors I described above had an ampacity equal to or greater than the setpoint of the feeder breaker, then 620.62 would come into play. But it would not be a tap rule situation, since the conductors are all protected at their ampacity by the breaker.

Welcome to the forum.
 
In the City of Tampa we always ask for a Selective Coordination Study when 2 or more elevators are supplied by the same feeder. A feeder can also be the bus in a MSB. Your inspector is correct in requesting the study.

COT Inspector
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
In the City of Tampa we always ask for a Selective Coordination Study when 2 or more elevators are supplied by the same feeder.
No surprise there. That is exactly what 620.62 requires.
A feeder can also be the bus in a MSB. Your inspector is correct in requesting the study.
I disagree with you there. The Article 100 definition of ?feeder? describes it as being ?circuit conductors.? A bus bar within a main switchboard is not a ?circuit conductor,? it is a component within a piece of listed equipment.
 
I also respectively disagree with your opinion.
How can a bus bar not be considered a conductor?
Since the NEC provides only 3 definitions in Article 100 for "conductor", none of which specifically says it has to be a wire, take a look at how Wikipedia defines an electrical conductor.

"Electrical conductor
In science and engineering, a conductor is a material which contains movable electric charges. In metallic conductors, such as copper or aluminium, the movable charged particles are electrons (See electrical conduction). Positive charges may also be mobile in the form of atoms in a lattice missing electrons (called "holes") or ions, such as in the electrolyte of a battery.

I don't see where a conductor has to be a "wire" by that definition.

Why would the NEC give us a calculation for Bus bar amperage if its not to be considered and used as a conductor?
Instead of running conduit and "wire" up a high rise to feed services, we install bus duct, which performs the same function as the conduit and "wire conductors".

So I would consider the bus bar in a MSB as the "circuit conductor" supplying the next level of overcurrent protective devices.

Just my opinion

COTInspector
 

radiopet

Senior Member
Location
Spotsylvania, VA
Just to add to this...In a recent discussion with NFPA and Mike Holt they both agreed that the load side of lets say a service disconnect is considered a feeder tap if you actually tapped the feeder conductors themselves or lets say the breaker had multiple lugs....they agree that either way it would be considered a feeder tap.

Just figured i would throw that in....others may disagree of course.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
I also respectively disagree with your opinion.
You are more than welcome to do so.

How can a bus bar not be considered a conductor?
Of course it's a conductor. It's just not a feeder. The NEC requirement under discussion is related to feeders.
, , , take a look at how Wikipedia defines an electrical conductor.
That I will not do. I have no respect whatsoever for that source of misinformation. Sorry, but being married to a librarian, I have been taught the difference between reliable sources and non-authoritative sources.
 

charlie b

Moderator
Staff member
Location
Lockport, IL
Occupation
Retired Electrical Engineer
. . . they both agreed that the load side of lets say a service disconnect is considered a feeder tap . . . .
We're not talking about taps (i.e., the points at which a wire is connected to another wire). We are talking about feeders (i.e., wires).
 
Status
Not open for further replies.
Top