Mag Loc ELectric Door Holders

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Fordean

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
I am installing mag loc in corridor. Trying to compute how far and how many.

Door Holder is 24 volt .015 amp @ 24v ac/dc

Board in fire alarm is rated at 2.5 amps Resistive loads.

wire gauge 14/2

Does T- tapping hamper system. Does it add more resistance to circuit. I know wire lenght does add resistance. I imagine Tapps add some negative effects as well.

Any formula I would appreciate.
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
I am installing mag loc in corridor. Trying to compute how far and how many.

Door Holder is 24 volt .015 amp @ 24v ac/dc

Board in fire alarm is rated at 2.5 amps Resistive loads.

wire gauge 14/2

Does T- tapping hamper system. Does it add more resistance to circuit. I know wire lenght does add resistance. I imagine Tapps add some negative effects as well.

Any formula I would appreciate.

Are you sure the available aux power on the FACP is 2.5 amps? Aux power outputs are more typically 300-500 mA (FireLite). Silent Knight panels may have what they call Flexput I/O's which are multi-purpose power limited outputs that can be NAC's, Aux power, or conventional smoke zones. These can get up to 3 amps. Otherwise, FACP's are rated at the power output for the entire panel, including all the NAC's, current to run the panel and any modules, and aux power.

T-taps, AFAIK, don't have particularly deleterious effects for this particular purpose. I think they're a bad idea in general because they can complicate troubleshooting, but maybe that's just me.
 

Fordean

Senior Member
Location
New Jersey
Occupation
Electrical Contractor
Are you sure the available aux power on the FACP is 2.5 amps? Aux power outputs are more typically 300-500 mA (FireLite). Silent Knight panels may have what they call Flexput I/O's which are multi-purpose power limited outputs that can be NAC's, Aux power, or conventional smoke zones. These can get up to 3 amps. Otherwise, FACP's are rated at the power output for the entire panel, including all the NAC's, current to run the panel and any modules, and aux power.

T-taps, AFAIK, don't have particularly deleterious effects for this particular purpose. I think they're a bad idea in general because they can complicate troubleshooting, but maybe that's just me.

its actually 2 amps not 2.5. @24 DC
 

gadfly56

Senior Member
Location
New Jersey
Occupation
Professional Engineer, Fire & Life Safety
its actually 2 amps not 2.5. @24 DC

OK, but what I'm getting at is that any individual output may be rated for almost all the power the panel can deliver. Each of your four (4) NAC's may be capable of delivering 3 amps, say, but the whole panel is a max of 6.5 amps. Voltage drop aside, I don't think you can expect to wire up 133 door holders to the aux power terminals when the demands of the rest of the panel components are taken into account.
 
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