Fire Pump Short-Circuit/OCPD

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Canton

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Location
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Electrician
I have a building where we are working that has a Combination ATS Fire Pump Controller. The Generator has a dedicated breaker that protects the Emergency feeder to the ATS/Controller. The Normal Feed comes underground directly from the Utility Transformer to the ATS/Controller...there is no Disconnect/OCPD for these Service Conductors from the Utility Transformer....? I have never seen this before. This Fire Pump room is in the main building but it is only accessible from a door on the outside of the building, no access from inside, if this even makes a difference.

I am use to seeing a TAP inside of the Gear before the Main Disconnect going to the Fire Pump Room and landing on a Seperate Disconnect with OCPD for Short Circuit/Ground Fault Protection fused at the LRC rating of the Fire Pump. There literally is no OCPD for this Fire Pump. Am I missing something? I have read 695 and cannot find anything to support not having protection on these conductors for Short Circuits/Ground Faults.

This is an Engineered Job with stamped drawings. Any ideas? :?
 
A service rated transfer switch fire pump controller combo may include all the OCPD that is required.
But the conductors leading to it are then service conductors which must run outside or protected by 2"+ of concrete.
 
GoldDigger said:
A service rated transfer switch fire pump controller combo may include all the OCPD that is required.
But the conductors leading to it are then service conductors which must run outside or protected by 2"+ of concrete.
Click to expand...

That is correct, the "Service Conductors" for normal power are run underground and outside from the Service Transformer to the Combo Fire Pump Controller/ATS. The problem is there is no OCPD anywhere........they terminate directly to the controller.
 
Canton said:
The problem is there is no OCPD anywhere........they terminate directly to the controller.
Click to expand...

Did you open the controller? If it is service rated I would expect it has OCP.

I have never seen a disco ahead of the utility feed to a fire pump ATS controller.
 
This seems to say that a disco and OCPD is not required fore a fire pump hooked directly to service feeders.:?

695.4 Continuity of Power
Circuits that supply electric motor-driven fire pumps shall
be supervised from inadvertent disconnection as covered in
695.4(A) or (B).
(A) Direct Connection. The supply conductors shall directly
connect the power source to either a listed fire pump
controller or listed combination fire pump controller and
power transfer switch.
 
jumper said:
This seems to say that a disco and OCPD is not required fore a fire pump hooked directly to service feeders.:?

695.4 Continuity of Power
Circuits that supply electric motor-driven fire pumps shall
be supervised from inadvertent disconnection as covered in
695.4(A) or (B).
(A) Direct Connection. The supply conductors shall directly
connect the power source to either a listed fire pump
controller or listed combination fire pump controller and
power transfer switch.
Click to expand...

Yep. If you do put in an OCPD, it has to be sized for 6X the locked rotor current. The conductors, however, only need to be sized for 125% of the FLA.
 
jumper said:
This seems to say that a disco and OCPD is not required fore a fire pump hooked directly to service feeders.:?

695.4 Continuity of Power
Circuits that supply electric motor-driven fire pumps shall
be supervised from inadvertent disconnection as covered in
695.4(A) or (B).
(A) Direct Connection. The supply conductors shall directly
connect the power source to either a listed fire pump
controller or listed combination fire pump controller and
power transfer switch.
Click to expand...

It is confusing... I'm stuck wondering if there was a short circuit or ground fault...and no ocpd?
 
Canton said:
I have a building where we are working that has a Combination ATS Fire Pump Controller. The Generator has a dedicated breaker that protects the Emergency feeder to the ATS/Controller. The Normal Feed comes underground directly from the Utility Transformer to the ATS/Controller...there is no Disconnect/OCPD for these Service Conductors from the Utility Transformer....? I have never seen this before. This Fire Pump room is in the main building but it is only accessible from a door on the outside of the building, no access from inside, if this even makes a difference.

I am use to seeing a TAP inside of the Gear before the Main Disconnect going to the Fire Pump Room and landing on a Seperate Disconnect with OCPD for Short Circuit/Ground Fault Protection fused at the LRC rating of the Fire Pump. There literally is no OCPD for this Fire Pump. Am I missing something? I have read 695 and cannot find anything to support not having protection on these conductors for Short Circuits/Ground Faults.

This is an Engineered Job with stamped drawings. Any ideas? :?
Click to expand...
For most installations this would be the best way to do it. It is compiant and simple. All full service fire pump controllers are SUSE rated for this reason.
 
iwire said:
Did you open the controller? If it is service rated I would expect it has OCP.

I have never seen a disco ahead of the utility feed to a fire pump ATS controller.
Click to expand...

I have done a few from buss taps to a service rated disco with ocpd and then onto the ats/controller. I have never done an install without ocpd.
 
Canton said:
It is confusing... I'm stuck wondering if there was a short circuit or ground fault...and no ocpd?
Click to expand...

Well, the short would eventually burn through...something. The safety trade off is that it's less risky for one or two people to be exposed to the potential electrical hazard than it is to have the fire pump off line if the high rise with 1,000 residents catches fire.
 
Canton said:
It is confusing... I'm stuck wondering if there was a short circuit or ground fault...and no ocpd?
Click to expand...
Service wires are always like this. The only protections are the POCO primary protection and thermal protection on their transformer and the wires melting.

For shorts after the pump controller, the controller overloads (set very high, since eventually burning out the pump motor is considered better than shutting it off any time before that during a fire) and any very high instant trip that might be inside the controller are all the protection those wires have, but that is considered protection enough under the circumstances.
 
GoldDigger said:
Service wires are always like this. The only protections are the POCO primary protection and thermal protection on their transformer and the wires melting.

For shorts after the pump controller, the controller overloads (set very high, since eventually burning out the pump motor is considered better than shutting it off any time before that during a fire) and any very high instant trip that might be inside the controller are all the protection those wires have, but that is considered protection enough under the circumstances.
Click to expand...

I don't think your seeing my question. I understand the service conductors not being protected up to a Main Disconnect/OCPD for the building. I understand that the intent for the OCPD on a fire pump being set so high is because they don't care what happens to the Fire Pump and they want it to run no matter what. This is installation has "NO OCPD" in any part of the normal power from the Utility Transformer to the controller/Disconnet to the Fire Pump.

A Fault at the Controller or Fire Pump would be catastrophic, the utility transformer is about 30' away on the other side of the wall. I'm just trying to see if this installation is compliant with no OCPD for Short Circuit/Ground Fault on the normal power?
 
gadfly56 said:
Whooops! My VERY bad. JUST the locked rotor current. For the 75HP pump that would be 543 amps at 460 three phase. Adjust for actual voltage accordingly.
Click to expand...

It is locked rotor current of the main motor + the full current load of the maintenance pump motor and the full load current of the fire pump accessories NEC 695.4 B(2)(A)
 
Canton said:
I don't think your seeing my question. I understand the service conductors not being protected up to a Main Disconnect/OCPD for the building. I understand that the intent for the OCPD on a fire pump being set so high is because they don't care what happens to the Fire Pump and they want it to run no matter what. This is installation has "NO OCPD" in any part of the normal power from the Utility Transformer to the controller/Disconnet to the Fire Pump.

A Fault at the Controller or Fire Pump would be catastrophic, the utility transformer is about 30' away on the other side of the wall. I'm just trying to see if this installation is compliant with no OCPD for Short Circuit/Ground Fault on the normal power?
Click to expand...

A full service listed fire pump controller with a SUSE rating can be directly connected to service conductors. It is the service disconnecting and OC protection. As long as the service conductors are outside the building (using the NEC definition of outside) it is compliant. See 695.4(A). While the UL standard does not require FP controllers to be SUSE rated, as a practical matter, I've never seen one that wasn't. As I mentioned previously, for most installations this is the simplest and least costly way to go.
In cases where you can't get service conductors directly to the FP controller without going through the building then you can use 695.4(B) and install the supply as a feeder. The big down side to this method is that the disconnect will have to be rated for locked rotor and the feeder installation will have to have a 2 hour fire rating. This can get quite costly.
 
texie said:
A full service listed fire pump controller with a SUSE rating can be directly connected to service conductors. It is the service disconnecting and OC protection. As long as the service conductors are outside the building (using the NEC definition of outside) it is compliant. See 695.4(A). While the UL standard does not require FP controllers to be SUSE rated, as a practical matter, I've never seen one that wasn't. As I mentioned previously, for most installations this is the simplest and least costly way to go.
In cases where you can't get service conductors directly to the FP controller without going through the building then you can use 695.4(B) and install the supply as a feeder. The big down side to this method is that the disconnect will have to be rated for locked rotor and the feeder installation will have to have a 2 hour fire rating. This can get quite costly.
Click to expand...

Yeah, no kidding on costly. UL pulled the listing for most of the cables formerly listed under UL2196. AFAIK, the only thing you can use is MI. I think iwire had some nice pics of an install under another thread.
 
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