Fire Pump ATS Size

[Sparky2791]

Good Evening,

I am working on a fire pump feed where we need to provide the ATS for the fire pump controller. It is not included with the controller.

I will be serving the normal side of the ATS via a separate utility company service. It is a 480V 3 phase 40HP Pump. Locked Rotor is indicated as 290A . Since I cannot route the service outside the building I will be adding the allowable OCP in the service disconnect and run it as a feeder with the listed fire rated cable through the building. Sizing the OCP for locked rotor means I will need 300A time delay fuses.The actual runnig Load Amps of the motor is marked on the motor as 42A. My question is since the actual RLA of the motor is only 42A Can I use a 100A transfer switch or since the OCP is set at 300A do I need a 400A transfer switch? I do not see anything about sizing the ATS.

Thanks for any comments!

 

[texie]

Good Evening,

I am working on a fire pump feed where we need to provide the ATS for the fire pump controller. It is not included with the controller.

I will be serving the normal side of the ATS via a separate utility company service. It is a 480V 3 phase 40HP Pump. Locked Rotor is indicated as 290A . Since I cannot route the service outside the building I will be adding the allowable OCP in the service disconnect and run it as a feeder with the listed fire rated cable through the building. Sizing the OCP for locked rotor means I will need 300A time delay fuses.The actual runnig Load Amps of the motor is marked on the motor as 42A. My question is since the actual RLA of the motor is only 42A Can I use a 100A transfer switch or since the OCP is set at 300A do I need a 400A transfer switch? I do not see anything about sizing the ATS.

Thanks for any comments!

ATS for fire pump duty must be specifically rated for fire pump duty-not just emergency rated. While the UL standard allows for a separate ATS and fire pump controller, as a practical matter I have never seen it done (at least that is compliant with code) due to a number of reasons. By far, and especially with a pump this size, the most common arrangement is a combination ATS/fire pump controller listed for the purpose. I'm not sure anyone even makes a stand alone fire pump rated ATS anymore, especially in this size.

 

[infinity]

ATS for fire pump duty must be specifically rated for fire pump duty-not just emergency rated. While the UL standard allows for a separate ATS and fire pump controller, as a practical matter I have never seen it done (at least that is compliant with code) due to a number of reasons. By far, and especially with a pump this size, the most common arrangement is a combination ATS/fire pump controller listed for the purpose. I'm not sure anyone even makes a stand alone fire pump rated ATS anymore, especially in this size.

I agree, the only ATS that I've ever installed for a fire pump is one that's integral to the controller.

 

[Sparky2791]

ATS for fire pump duty must be specifically rated for fire pump duty-not just emergency rated. While the UL standard allows for a separate ATS and fire pump controller, as a practical matter I have never seen it done (at least that is compliant with code) due to a number of reasons. By far, and especially with a pump this size, the most common arrangement is a combination ATS/fire pump controller listed for the purpose. I'm not sure anyone even makes a stand alone fire pump rated ATS anymore, especially in this size.

They do make them. Look at the cut sheet here https://www.thebigredguide.com/docs/fullspec/pd902-50(a).pdf or search for Firetrol FTA902
fully compliant with being rated for fire pump use. Available up to 800A.
So... would it need to be a 400A switch even though running current is only 42A?
The controller already exists but a mistake was made and it was installed without a transfer switch so now one needs to be added to an existing installation.

 

[Ingenieur]

this may help http://studylib.net/doc/10795288/fta902--903--952-953-separately-mounted-power-transfer-sw...

looks like it is based on fla and hp
and since rated for fire pump use the lra would be factored in

best to verify with mfg