Article 620.51 - Shunt Trip

[Npstewart]

Article 620 is written specifically for dumbwaiters, escalators, elevators etc. Article 620.51 (B) permits the elevator to be shunt tripped when the sprinkler system goes off. Would a shunt trip be required for a dumbwaiter if it was large enough to carry a person?

 

[Smart $]

Not real familiar with 620, but seems rather unsafe if a shunt trip was required. What if a person was actually in the dumbwaiter when it was tripped. With manual reset required, hard to tell how long that person may be in there... :blink:

 

[gadfly56]

Not real familiar with 620, but seems rather unsafe if a shunt trip was required. What if a person was actually in the dumbwaiter when it was tripped. With manual reset required, hard to tell how long that person may be in there... :blink:

Besides the fact that dumbwaiters, by their nature, aren't for use by people (notwithstanding multiple scenes from "The Spiderwick Chronicles"), this is exactly what happens with passenger service elevators. Heat detector "on" -> shunt trip "off" -> elevator stop -> sprinkler "on".

 

[GoldDigger]

Am I correct in assuming that the sprinkler system in question is just the sprinklers in the elevator or hoist shaft?
I would hate to lock out the elevators while they are in use based on a sprinkler activation anywhere in the building. That would rather solidly defeat the safe floor recall and fireman operation systems.

 

[gadfly56]

Am I correct in assuming that the sprinkler system in question is just the sprinklers in the elevator or hoist shaft?
I would hate to lock out the elevators while they are in use based on a sprinkler activation anywhere in the building. That would rather solidly defeat the safe floor recall and fireman operation systems.

Yes, specifically the hoistway and elevator machine room. If the hoistway has a sprinkler in it that's listed to activate at 165F (let's say), you put a heat detector within 2 feet of the sprinkler that activates at 135F (let's say). Since you're likely to be using an addressable fire alarm system, that detector's output is mapped to the input group for the fire alarm system elevator shunt trip relay. The relay activates, the shunt coil goes hot and the elevator shuts down. Wherever it happens to be.