Douglas Krantz - Technical Writer - Describing How It Works
Go to the Writer Home Page of Douglas Krantz -- Describing How It Works
Go to the Fire Alarm Operation Map Page of Douglas Krantz - Technical Writer
Go to the General Electrical Map Page of Douglas Krantz - Technical Writer
Go to the Fire Alarm Description Map Page of Douglas Krantz - Technical Writer
Go to the Fire Alarm Installing Map Page of Douglas Krantz - Technical Writer
Go to the Fire Alarm Maintaining Map Page of Douglas Krantz - Technical Writer
Go to the Fire Alarm Testing Map Page of Douglas Krantz - Technical Writer
Go to the Fire Suppression Map Page of Douglas Krantz - Technical Writer


I have a question about something

T Wrote:

Hi Doug,

While trying to trouble shoot why the door release for the front door is not working, one of the conductors grounded out against the fire alarm panel chases. This caused the door release to activate.

It is not activating when the relay changes state in alarm. Nothing is happening. Yet when one of the conductors grounds, it activates the door release.

Any thoughts?

Thank you in advance for your help.

Douglas Krantz Wrote:

It sounds like the wire contacting the side of the fire alarm panel is either shorting out the power supply (cutting power to the door release) or making a complete electrical circuit when the wire is grounded (providing power to the release). In either case, the circuit has a second ground connection.

Most security and fire alarm power supplies aren't connected to ground on the low voltage side, but because this door release sounds like it could be for security purposes, anything goes for the power supply. If the power supply is grounded, making contact to chase with the wire would cause this effect.

If there is a door operator (the type that opens the door automatically), the door operator itself is often wired weird, so anything goes with the door operator as far as a second ground. A second ground may be normal.

If the door release is a Von Duprin type of door strike/panic bar, this has its own power supply and possibilities of wiring issues. Anyone could have wired this originally and made some weird connections. In this case, a second ground might be normal.

If it is a Von Duprin door strike/panic bar, check the wire size from the Von Duprin power supply to the door. (It needs to be 12 or 14 gauge.) Smaller than what is shown in the installation sheets supplied with the door release could be the issue. I've seen this issue show up after a year of the door release working flawlessly. The contractor then made the electrician rerun the wires with the proper size wires, which fixed the problem.

Also, if it is a panic bar, often the wires for the bar or door release may go through the door hinges (this is one of the possibilities of how the wires get to the door), and in order to run the wires through the hinge, they're very thin. There could be a break inside one of these hinges, and if one of the broken wires is grounded when it shouldn't be, that could be the second ground. In this case, the ground is not normal.

Another possibility is that there is a "Touch Type" panic bar or door handle that also electronically activates the door release. This could have an issue with the actual release circuit for the door. With these things, anything goes.

Often the whole door lock/release system is installed by three or more different vendors at many different times. None of them really know what the others has done. This scenario becomes a nightmare when trying to troubleshoot. The grounded system might or might not be normal.

When you add these possibilities to problems with the original installation, the door entry system, and the card access system (which could all be involved), without being there, it becomes very difficult to make guesses as to what could be causing the problem with grounding the wire to the chase.

Basically, fix the door release problem first. Worry about the grounding of the system later. Often fixing the release will fix the ground problem, that is if the grounded system is actually a problem.






Popular Articles

What is a Stair Pressurization Fan (SPF)? -- In case of fire in a high rise building, an SPF uses clean outside air to pressurize the air in stairwells. The pressurized air helps people escape... Read More

How Does Class A Fire Alarm Wiring Work?-- Fire alarm systems save lives and protect property. Fire alarm systems also break down because... Read More

What's the Difference Between Class A and Class B? -- The Fire Alarm System is a Life Safety System - so the occupants of a building can escape quickly, the idea behind a Fire Alarm System is that it will provide a warning that there is a fire. The trouble is, if something is wrong with the system, like a wire is broken somewhere in the building, the Fire Alarm System... Read More

What is a Flyback Diode? -- Someone Thinks the Flyback Diode is Important. Manufacturers all over the world spend good money installing these diodes, they must think they're ... Read More

What is a Waterflow Switch? -- The fire alarm waterflow switch, a delayed action mechanical/electrical assembly, is a conventionally wired fire alarm device. The fire department reacts... Read More

What Should I Do When the Fire Alarm Sounds? -- When the alarm sounds, as caretaker for an apartment building, what should you be doing? "I would never suggest turning off the fire alarms, or in any way... Read More

What is a Fire Alarm System? -- Long ago, as earliest method of spreading the word of fire danger, people shouted "Fire!" Depending on the circumstances, people would run... Read More

What Does E=IR Really Mean? -- If it isn't just a word, and it isn't really something to be memorized in order to pass a test, what do the letters in Ohm's Law really mean?... Read More