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Sprinkler Pump Supplies

Former Community Member
Former Community Member

Hello, I have read in the Forums that a sprinkler pump has to be connected directly to the DNO supply so that if the building is isolated the sprinkler pump/life services systems aren't.

My question is that how do you rate the cable to the life services panel i.e. if the DNO protective device is a 1250A MCCB, does the life safety cable connection to the DNO supply have to be 1250A rated? Or can it be downrated to the actual load?

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    I think you have mis-understood ‘directly’ - directly in the sense of via a fuse that is not shared with anything else may make the intention clearer - depends on the supply you need but for an example a  100A fuse would warrant a 100A main from that point onwards.  The fuse may well need too be quite be oversized for the load by normal standards - if push comes to shove you may not care if the motor is running a bit hot,  it just needs to keep running so a finely set  overload protection is not needed or desirable.

    Another similar discussion from a few years back that sets the tone

    Mike

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    I think you have mis-understood ‘directly’ - directly in the sense of via a fuse that is not shared with anything else may make the intention clearer - depends on the supply you need but for an example a  100A fuse would warrant a 100A main from that point onwards.  The fuse may well need too be quite be oversized for the load by normal standards - if push comes to shove you may not care if the motor is running a bit hot,  it just needs to keep running so a finely set  overload protection is not needed or desirable.

    Another similar discussion from a few years back that sets the tone

    Mike

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