shunt trip

Status
Not open for further replies.

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
Question is this a code rule or is it the elevator state inspector my reason is why would they use a shunt on a elevator .

One reason was already mentioned: If there are sprinklers inside the elevator shaft you may want to cut power to the cage and/or elevator motor before spraying water on it.
Not all shunt trips are for manual shutdown.
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
...

We don't used the mains on service for this, the shunt trips are (big yellow) or( red momentary buttons) which are mounted at 7 feet high on outside of a building in one location there labeled shunt trip and each is identified with a plate stating what it is disconnecting. It also can be in located in a security room which is mounted so the security team or anyone that needs to disconnect power can.

So is it in the code book is it in the NEC ?
Without a lock? Wow....I know many people who would push buttons like that just because they are there.
 

ADub

Senior Member
Location
Midwest
Occupation
Electrician
Question is this a code rule or is it the elevator state inspector my reason is why would they use a shunt on a elevator .

So the power is opened if the sprinkler goes off


Sent from my iPhone using Tapatalk
 

Ingenieur

Senior Member
Location
Earth
A shunt trip is required on elevator power when the shaft is sprinklered
A17.1 and nfpa 20?

it is tripped by thermal detectors with a setting lower than the sprinkler rating
 

luckylerado

Senior Member
No, it is not. If required, it's either a spec requirement or a local amendment.

Question is this a code rule or is it the elevator state inspector my reason is why would they use a shunt on a elevator .

It is required in the elevator code when sprinkled and is usually triggered by a heat detector. ASME A17.1-2010, Section 2.8.3.3.2 requires an automatic, non-resetting means independent of the elevator control to disconnect the main line power to the elevator before sprinkler water is discharged into the machine room or machinery spaces including the hoistway.

Although this could be accomplished with a latching or mechanically held relay I have never seen anything other than a shunt trip breaker used.

NEC 620.51(B) "the disconnecting means shall be permitted to automatically open the power supply to the affected elevator(s) prior to the application of water. "

NFPA 72 requires the shunt trip control circuit to be monitored by the fire alarm system.
21.4.4* Control circuits to shut down elevator power shall be monitored for the presence of operating voltage. Loss of voltage to the control circuit for the disconnecting means shall cause a supervisory signal to be indicated at the control unit and required remote annunciators.
 

kwired

Electron manager
Location
NE Nebraska
I know nearly nothing on elevator codes, but sure seems to me that one of last things you want to do is shut it down while there are passengers in it. I can see requirements that allow for stopping it at nearest possible point where passengers could exit and allowance for doors to open before any other shutdown occurs. Maybe there is a bigger picture that I am not aware of though.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
It is required in the elevator code when sprinkled and is usually triggered by a heat detector. ASME A17.1-2010, Section 2.8.3.3.2 requires an automatic, non-resetting means independent of the elevator control to disconnect the main line power to the elevator before sprinkler water is discharged into the machine room or machinery spaces including the hoistway.

Although this could be accomplished with a latching or mechanically held relay I have never seen anything other than a shunt trip breaker used.

NEC 620.51(B) "the disconnecting means shall be permitted to automatically open the power supply to the affected elevator(s) prior to the application of water. "

NFPA 72 requires the shunt trip control circuit to be monitored by the fire alarm system.
21.4.4* Control circuits to shut down elevator power shall be monitored for the presence of operating voltage. Loss of voltage to the control circuit for the disconnecting means shall cause a supervisory signal to be indicated at the control unit and required remote annunciators.

My response was to the general requirement for shunt trips to allow remote shutdown of facility-wide power, not about elevators. Nowhere in the comment I responded to does it mention elevators. I was trying to get the thread back on topic. Read before you post.
 

Ingenieur

Senior Member
Location
Earth
I know nearly nothing on elevator codes, but sure seems to me that one of last things you want to do is shut it down while there are passengers in it. I can see requirements that allow for stopping it at nearest possible point where passengers could exit and allowance for doors to open before any other shutdown occurs. Maybe there is a bigger picture that I am not aware of though.

I am a certified QEI
in fact annual ceu seminar next week in ocean city md

the logic is water on the controls can cause serious problems
hoistway doors to open with no car at landing
elevator to run by slow down or final switches
get safeties wet and reduce effectivness
etc

they just don't shut the power off
first bldg smoke detectors will park the car at a landing (more sensitive and trip well before thermal)
shaft mounted smoke det do the same
then heat detectors at say 135 F with shunt trip
then sprinklers at 160 F

elevators have so many layers of safety, both elec and mech, that they are extremely safe machines
IF MAINTAINED PROPERLY
 
Last edited:

kwired

Electron manager
Location
NE Nebraska
I am a certified QEI
in fact annual ceu seminar next week in ocean city md

the logic is water on the controls can cause serious problems
hoistway doors to open with no car at landing
elevator to run by slow down or final switches
get safeties wer and reduce effectivness
etc

they just don't shut the power off
first smoke detectors will park the car at a landing (more sensitive and trip well before thermal)
then heat detectors at say 135 F with shunt trip
then sprinklers at 160 F

elevators have so many layers of safety, both elec and mech, that they are extremely safe machines
IF MAINTAINED PROPERLY
Thanks, I didn't think they would just shut them off upon detection of fire or other hazards, but rather make every possible effort to safely allow evacuation of the car before anything gets shut down.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
Thanks, I didn't think they would just shut them off upon detection of fire or other hazards, but rather make every possible effort to safely allow evacuation of the car before anything gets shut down.

The really sensitive issue is that smoke recall will bring the car down to the primary recall floor (usually) and open the doors. Then the fire fighters arrive, put their key in and use the car to stage men and equipment wherever their action plan calls for. Since their key overrides the elevator safety sequence, there is usually no way to do a second recall in the event the heat detector goes off. There is a potential for responders to be inside the car when the power dies. And if there's already enough heat to trip the sprinkler, here's hoping it keeps the fire at bay long enough to evac the responders. There needs to be more discussion on this issue between the fire alarm folks and the elevator folks, with the fire service thrown in for good measure.
 

Ingenieur

Senior Member
Location
Earth
Thanks, I didn't think they would just shut them off upon detection of fire or other hazards, but rather make every possible effort to safely allow evacuation of the car before anything gets shut down.


Hoistway construction is essentially fireproof
only elevator equipment is allowed in it, no misc power, plumbing, etc
chance of fire is small other than a flue effect and that has measures to mitigate
fire fighters can override and move elevators in emergency modes

there is like 60000 elevators in nyc and very few accidents
but they do happen
seldom catastrophic failure
usually poor maintenance, inspection and testing
bad car or hoistway door switches
landing switches/interlocks

900,000 in the us http://www.neii.org/presskit/printmaster.cfm?plink=NEII Elevator and Escalator Fun Facts.cfm

elevator inspectors are in big demand
one of the highest demand non college professions
I get opportunities weekly
part time work is part of my retirement plan lol
 
Last edited:

ohmhead

Senior Member
Location
ORLANDO FLA
One reason was already mentioned: If there are sprinklers inside the elevator shaft you may want to cut power to the cage and/or elevator motor before spraying water on it.
Not all shunt trips are for manual shutdown.

Yes we shunt elevator off when there is a fire in shaft but its done with the combo LSP control switch I guess your calling that out as a shunt button but its a breaker inside a cabinet with fire alarm relays if sprinkler is in the pit or a fire in shaft . Yes we also have a micro switch in the disconnect if we don't use the LSP control module . But we never use a shunt trip button ever. But my question was about switchgear services powering the building .
 

ohmhead

Senior Member
Location
ORLANDO FLA
Without a lock? Wow....I know many people who would push buttons like that just because they are there.
That's a wp break glass button or buttons , yes its done all the time, there can not be a lock on a shunt trip emergency shunt button that would defeat the purpose the reason its installed for or what it was designed for why would you want lock out a shunt button . Never heard of anyone locking a emergency shunt button the building inspector or fire Marshall would not let that happen .
 

iwire

Moderator
Staff member
Location
Massachusetts
That's a wp break glass button or buttons , yes its done all the time, there can not be a lock on a shunt trip emergency shunt button that would defeat the purpose the reason its installed for or what it was designed for why would you want lock out a shunt button . Never heard of anyone locking a emergency shunt button the building inspector or fire Marshall would not let that happen .

This is nuts. :)

In the buildings we do locate shunt trips they will be inside a locked door, the fire department is more than capable of getting through a locked door.

You don't see a danger to public safety having a shunt trip that some drunk could hit at anytime while there is a full house in this stadium?
 

ohmhead

Senior Member
Location
ORLANDO FLA
So the power is opened if the sprinkler goes off


Sent from my iPhone using Tapatalk

No its shut down by LPS disconnect but its not a shunt trip button it only operates by a breaker controlled by heat detectors in shaft or elevator machine room I think we got off to elevators I was interested in the shunt trip button on main service which has nothing to do with elevators at all .
 

ohmhead

Senior Member
Location
ORLANDO FLA
This is nuts. :)

In the buildings we do locate shunt trips they will be inside a locked door, the fire department is more than capable of getting through a locked door.

You don't see a danger to public safety having a shunt trip that some drunk could hit at anytime while there is a full house in this stadium?

We install them outside or inside the building depends on engineer or plans mostly there in the main security room and there in a row labeled and there break glass inside if outside the building code or fire Marshall says 7 foot above grade. Whats nuts about it ?
 

iwire

Moderator
Staff member
Location
Massachusetts
No its shut down by LPS disconnect but its not a shunt trip button it only operates by a breaker controlled by heat detectors in shaft or elevator machine room I think we got off to elevators I was interested in the shunt trip button on main service which has nothing to do with elevators at all .

That is a shunt trip, the 'shunt' is a device in the breaker. But I do understand you are asking about the main not the elevator.
 

iwire

Moderator
Staff member
Location
Massachusetts
We install them outside or inside the building depends on engineer or plans mostly there in the main security room and there in a row labeled and there break glass inside if outside the building code or fire Marshall says 7 foot above grade. Whats nuts about it ?

I said what is nuts about it, the fact that any moron can kill the power to a stadium at any time is in my opinion a public safety issue in itself.

I understand you are just doing what is required as I would as well but it is still stupid.
 

kwired

Electron manager
Location
NE Nebraska
I said what is nuts about it, the fact that any moron can kill the power to a stadium at any time is in my opinion a public safety issue in itself.

I understand you are just doing what is required as I would as well but it is still stupid.
I can understand the control being in the main security rooom or other managed area. Chances are if there is a full house such areas are being staffed. General public accessible areas is not a good place for them, even at 7 feet high. People don't even have to be drunk after some wild events to do some stupid things, but a little alcohol does give them even more courage to do things they ordinarily wouldn't do.

Remember the good ol days of fans charging the field and tearing down goal posts after a big win? You don't see that anymore, which is probably good, but was still fun to watch on TV.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
I said what is nuts about it, the fact that any moron can kill the power to a stadium at any time is in my opinion a public safety issue in itself.

I understand you are just doing what is required as I would as well but it is still stupid.

Agreed. I usually measure 8' ceilings by raising my hands and touching them. I can't believe this would be required unless installed in the FACP with a 3' sign above it that reads "THIS BUTTON WILL SHUT POWER OFF TO THE ENTIRE BUILDING. PUSH THIS BY MISTAKE AND GO TO JAIL."
 
Status
Not open for further replies.
Top