If you tap a switchboard's buss ahead of the main service switch to to feed a 60 amp fire alarm fused disconnect and distance exceeds 10', do the tap conductors need to be sized at 1/3rd the ampacity of the main service switch if the distance is than 25'? I can't imagine running 833 amps into a 60 amp switch.
Do tap rules apply to service taps?
- Thread starter cppoly
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electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Feeder tap rules do not apply to services. See here
http://forums.mikeholt.com/showthread.php?t=174264&highlight=Service+taps
http://forums.mikeholt.com/showthread.php?t=174264&highlight=Service+taps
kwired
Electron manager
- Location
- NE Nebraska
They are not a "feeder tap".
Service conductors are limited on how much can enter a building because there is no (intentional) overcurrent protection ahead of them.
You could run same size conductor all the way to the supply transformer and it still is not a feeder tap.
But either way is still a service conductor.
Service conductors are limited on how much can enter a building because there is no (intentional) overcurrent protection ahead of them.
You could run same size conductor all the way to the supply transformer and it still is not a feeder tap.
But either way is still a service conductor.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Would not that FA disconnect need to be qrouped the other service discos?
kwired
Electron manager
- Location
- NE Nebraska
yes. depending on how the AHJ interprets "nearest the point of entry" could limit just how much of the run needs to be installed so that it is not considered inside the building, even if only a short distance to the equipment where the "tap" was made.
I don't believe this supply to the FA would be permitted to be a additional service disconnect beyond the six that are generally permitted either so the six disconnect rule also applies.
More common may be a supply side tap to a fire pump, but that is required to be separate service and normally required to be remote from the general service equipment. Still must run the "tap" in a way that it is considered outside the building because it is still service conductors and not a feeder tap.
It could be considered to be a separate service under 230.2(A)(2).
kwired
Electron manager
- Location
- NE Nebraska
The arrangement mentioned is not a separate service it is just an additional service disconnect on one service. One service drop or service lateral shall supply one service - somewhere in art 230 says that or something very close to that, I didn't look for it.
230.2(A)(2) "emergency systems" I believe is referring to art 700 systems, such systems maybe could supply the FA but the FA itself is not an art 700 system AFAIK.
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