Fire pump and Jockey Pump Coordination

[Tainted]

I have a 400A fuse feed 20HP fire pump fused at 350A and a 1HP jockey pump fused 15A.


It's quite easy to coordinate the 400A fuse with a 15A fuse, but how can you coordinate a 400A fuse with a 350A fuse? It's harder to coordinate overcurrent protections the closer the value is to the main.

 

[d0nut]

You are correct in that you probably cannot find a fuse combination that will coordinate at those sizes. You will probably end up needing to remove the overcurrent devices from the fire pump disconnect or remove the jockey pump from that service.

I realize that this is already installed so the solutions are more limited, but this is why I always use service rated fire pump controllers and provide no upstream overcurrent protection or disconnecting means. Selective coordination is easy when you only have one device.

 

[Tainted]

You are correct in that you probably cannot find a fuse combination that will coordinate at those sizes. You will probably end up needing to remove the overcurrent devices from the fire pump disconnect or remove the jockey pump from that service.

I realize that this is already installed so the solutions are more limited, but this is why I always use service rated fire pump controllers and provide no upstream overcurrent protection or disconnecting means. Selective coordination is easy when you only have one device.

If the jockey pump is not considered an emergency circuit, wouldn't it not matter if the 400A fuse is coordinated with the 350A fuse? Who cares if the jockey pump has no power? The real emergency circuit is the fire pump.

 

[don_resqcapt19]

From a real world view, I see no need to coordinate between the 400 and 350....no matter what one opens the fire pump stops.
From a code standpoint I would ignore the jockey pump and apply the exception to 700.32 for the two fuses in series.

 

[d0nut]

From a logic standpoint, I agree. I think you will run into issues with the definition of selective coordination. The exception to the selective coordination requirements is that it isn't required between two overcurrent devices located in series if no loads are connected in parallel with the downstream device. I think you run into an issue with meeting the exception.

That being said, I think you have a bigger issue with the installation. The requirement for selective coordination in 695 is for multi-building campus-style complexes fed from feeder sources, which is not what you have in your installation. I still think you have more disconnecting means and overcurrent devices than you are permitted. You are only permitted one disconnecting means and associated overcurrent protective device between the fire pump power source and the fire pump controller per 695.4(B)(1). Your installation has two.

 

[Tainted]

From a logic standpoint, I agree. I think you will run into issues with the definition of selective coordination. The exception to the selective coordination requirements is that it isn't required between two overcurrent devices located in series if no loads are connected in parallel with the downstream device. I think you run into an issue with meeting the exception.

That being said, I think you have a bigger issue with the installation. The requirement for selective coordination in 695 is for multi-building campus-style complexes fed from feeder sources, which is not what you have in your installation. I still think you have more disconnecting means and overcurrent devices than you are permitted. You are only permitted one disconnecting means and associated overcurrent protective device between the fire pump power source and the fire pump controller per 695.4(B)(1). Your installation has two.

This might be true for the new codes, but I don't really see the restriction on the number of disconnecting means in the NYC electrical code

 

[Tainted]

From a logic standpoint, I agree. I think you will run into issues with the definition of selective coordination. The exception to the selective coordination requirements is that it isn't required between two overcurrent devices located in series if no loads are connected in parallel with the downstream device. I think you run into an issue with meeting the exception.

That being said, I think you have a bigger issue with the installation. The requirement for selective coordination in 695 is for multi-building campus-style complexes fed from feeder sources, which is not what you have in your installation. I still think you have more disconnecting means and overcurrent devices than you are permitted. You are only permitted one disconnecting means and associated overcurrent protective device between the fire pump power source and the fire pump controller per 695.4(B)(1). Your installation has two.

I found this in the NYC electrical code 695.4(A) see in bold:

(A) General. Each utility and generator supply circuit that supplies an electric motor-driven fire pump or limited service fire pump shall be supplied from a single dedicated service disconnecting means and associated overcurrent protective device installed between the power source and one of the following:
(1) A listed fire pump controller
(2) A listed fire pump power transfer switch
(3) A listed combination fire pump controller and power transfer switch

I understand that a fire pump must have a single dedicated service disconnecting means based on the statement above, but is it saying that there must be a single overcurrent protective device too? It is not saying "from a single dedicated overcurrent protective device"