Fire Alarm Branch Circuit Locking Device

[luckylerado]

NFPA 72 requires:

"10.6.5.4 Circuit Breaker Lock. Where a circuit breaker is the
disconnecting means, an approved breaker locking device
shall be installed."

My take has always been this means locked in the closed position. I have an inspector interpreting this to mean a lockout device must be installed on the breaker so as to lock the breaker out while servicing.

Thoughts? I do not see this requirement in NFPA 70. Is there any other reference that makes this more clear?

 

[gadfly56]

NFPA 72 requires:

"10.6.5.4 Circuit Breaker Lock. Where a circuit breaker is the
disconnecting means, an approved breaker locking device
shall be installed."

My take has always been this means locked in the closed position. I have an inspector interpreting this to mean a lockout device must be installed on the breaker so as to lock the breaker out while servicing.

Thoughts? I do not see this requirement in NFPA 70. Is there any other reference that makes this more clear?

The purpose is to keep the breaker locked in the "on" position. I suppose you could use it to lock the breaker "off" as well during servicing , but that's not the primary purpose. You don't want someone to do "hunt the breaker" and flip off the fire alarm panel in the process.

 

[luckylerado]

The purpose is to keep the breaker locked in the "on" position. I suppose you could use it to lock the breaker "off" as well during servicing , but that's not the primary purpose. You don't want someone to do "hunt the breaker" and flip off the fire alarm panel in the process.

I agree

 

[jumper]

NFPA 72 requires:

"10.6.5.4 Circuit Breaker Lock. Where a circuit breaker is the
disconnecting means, an approved breaker locking device
shall be installed."

My take has always been this means locked in the closed position. I have an inspector interpreting this to mean a lockout device must be installed on the breaker so as to lock the breaker out while servicing.

Thoughts? I do not see this requirement in NFPA 70. Is there any other reference that makes this more clear?

Closet I could find.

760.41 NPLFA Circuit Power Source Requirements.
(A) Power Source. The power source of non–power limited
fire alarm circuits shall comply with Chapters 1
through 4, and the output voltage shall be not more than
600 volts, nominal. The fire alarm circuit disconnect shall
be permitted to be secured in the “on” position.

 

[gadfly56]

Closet I could find.

760.41 NPLFA Circuit Power Source Requirements.
(A) Power Source. The power source of non–power limited
fire alarm circuits shall comply with Chapters 1
through 4, and the output voltage shall be not more than
600 volts, nominal. The fire alarm circuit disconnect shall
be permitted to be secured in the “on” position.

Good find!

 

[steve66]

I always thought the same thing - lock on. But your inspector may be right.

I have an older NFPA 72 handbook, which doesn't have any specific requirement for a lock, but it says the breaker shall only be accessible to authorized people. The commentary explains that is to help prevent tampering, inadvertent shutoff, and also to aid in troubleshooting and servicing.

I wonder if a panel with a lockable front cover helps in any way?

Most of the time I just see a setscrew clamp on the breaker. Those can be used in either position, but I'm not sure that meets the latest requirements since its not actually a lock.

 

[gadfly56]

I always thought the same thing - lock on. But your inspector may be right.

I have an older NFPA 72 handbook, which doesn't have any specific requirement for a lock, but it says the breaker shall only be accessible to authorized people. The commentary explains that is to help prevent tampering, inadvertent shutoff, and also to aid in troubleshooting and servicing.

I wonder if a panel with a lockable front cover helps in any way?

Most of the time I just see a setscrew clamp on the breaker. Those can be used in either position, but I'm not sure that meets the latest requirements since its not actually a lock.

It's still good. The intent is to prevent inadvertent shut off, not be a LOTO component. If you have to loosen a set screw to operate the breaker handle you have to really intend to do it.

 

[Coppersmith]

If a breaker handle is locked in the on position, can the breaker still trip if there is an overcurrent/short?

 

[retirede]

If a breaker handle is locked in the on position, can the breaker still trip if there is an overcurrent/short?

Yes

 

[gadfly56]

If a breaker handle is locked in the on position, can the breaker still trip if there is an overcurrent/short?

Yes. Breakers have an internal mechanism that does not require the handle to move. If you're feeling adventurous, try it the next time you run into a stubborn CB. When I was young and foolish, there was some circumstance where I decided to hold a breaker closed. It tripped anyway, and I had to release the handle to reset the breaker. I don't remember the specifics, but fortunately I stopped doing that before I burned anything down.

 

[Coppersmith]

Yes

Yes. Breakers have an internal mechanism that does not require the handle to move. If you're feeling adventurous, try it the next time you run into a stubborn CB. When I was young and foolish, there was some circumstance where I decided to hold a breaker closed. It tripped anyway, and I had to release the handle to reset the breaker. I don't remember the specifics, but fortunately I stopped doing that before I burned anything down.

Thanks. That makes me feel a little better about resetting a breaker that is tripping due to a short.

 

[Codegui2]

Further thoughts on Lock-On requirements

Further thoughts on Lock-On requirements

760.41 NPLFA Circuit Power Source Requirements.
(A) Power Source. The power source of non–power limited
fire alarm circuits shall comply with Chapters 1
through 4, and the output voltage shall be not more than
600 volts, nominal. The fire alarm circuit disconnect shall
be permitted to be secured in the “on” position.

Do you believe that this requirement is for all power to separate fire alarm devices which we typically find powered separately such as the fire alarm bell, elevator smoke detectors, shut trips on elevators, etc.?

 

[steve66]

760.41 NPLFA Circuit Power Source Requirements.
(A) Power Source. The power source of non–power limited
fire alarm circuits shall comply with Chapters 1
through 4, and the output voltage shall be not more than
600 volts, nominal. The fire alarm circuit disconnect shall
be permitted to be secured in the “on” position.

Do you believe that this requirement is for all power to separate fire alarm devices which we typically find powered separately such as the fire alarm bell, elevator smoke detectors, shut trips on elevators, etc.?

To be honest, I didn't realize bells took a separate power supply. And I've always just seen the elevator smoke detectors powered from the FA panel.

Elevator shunt trips require their voltage to be monitored, to be sure they are ready to operate.

It's simple and easy to provide the handle clamp on multiple breakers, but I'm not sure its required for anything other than the actual FA panel supply.

 

[gadfly56]

760.41 NPLFA Circuit Power Source Requirements.
(A) Power Source. The power source of non–power limited
fire alarm circuits shall comply with Chapters 1
through 4, and the output voltage shall be not more than
600 volts, nominal. The fire alarm circuit disconnect shall
be permitted to be secured in the “on” position.

Do you believe that this requirement is for all power to separate fire alarm devices which we typically find powered separately such as the fire alarm bell, elevator smoke detectors, shut trips on elevators, etc.?

On smaller systems, you should never see the fire alarm bell on a separate circuit, they are typically powered by the fire alarm control panel (FACP). For larger systems, you may have notification appliance booster power supplies. The breaker rule applies to them as well.

I don't know where you are or the system you have where elevator smoke detectors are powered apart from the FACP. Even if they are 4-wire detectors, the power should come from the FACP. Can you provide more information?

 

[david luchini]

Closet I could find.

Get out of the closet.

 

[Codegui2]

Strange arrangement

Strange arrangement

This is low rise multi- family residential units and in all six buildings as this photo depicts the installer has a lock-on device for the fire alarm, but installed the fire bell on another circuit called "flow switch" two breakers above it and also installed the smoke detectors above that and labeled it "Smoke guard". I would think all should be connected to the fire alarm circuit and it should be colored red at the handle or lock-on device as well. The engineered drawings do not show separate breakers for the flow switch to activate the fire bell or smoke detectors. There does not seem to be a rule against it though.

 

[gadfly56]

This is low rise multi- family residential units and in all six buildings as this photo depicts the installer has a lock-on device for the fire alarm, but installed the fire bell on another circuit called "flow switch" two breakers above it and also installed the smoke detectors above that and labeled it "Smoke guard". I would think all should be connected to the fire alarm circuit and it should be colored red at the handle or lock-on device as well. The engineered drawings do not show separate breakers for the flow switch to activate the fire bell or smoke detectors. There does not seem to be a rule against it though.

View attachment 19712

Here's my guess. Based on the label "flow switch", the building is sprinklered. The "fire alarm" is probably a communicator that monitors ONLY the flow switch and maybe a couple of tampers and sends the signals to a central station. The "smoke guard" is probably a collection of 120VAC smoke alarms located in the public areas (laundry room, tenant storage, hallways) that are not connected to the "fire alarm". The flow switch is likely a System Sensor or Potter DPDT, with one set of contacts going to the fire alarm/communicator and the other acting as a switch for a 120VAC bell that is located on the exterior of the building and operates as long as water flow is present. It is likely the bare minimum code-compliant design possible for this occupancy.