Grill The Fire Expert

Oct. 27, 2008
Using Access Control Wiring and Communicator/Detector Issues

Mixing It Up with Access Control Cables
Can I install access control wiring (12VDC) in the same conduit as power-limited (24VDC) fire alarm wiring as long as I follow NFPA 70’s wiring methods? If I read Art.760.56 of NFPA 70 (2002) correctly, it would be allowed.

A: If it is with power-limited fire alarm wiring...Yes.

This wiring rule is also found in the same place (760.56) in the 2005 edition of the NEC and specifically allows Class 2 circuits to be installed together with power-limited fire alarm cables.

If it is with certain audio circuit wiring...No.

Article 725.56 (F) and 760.56 (D) are new rules in the 2005 edition of the NEC and prohibit mixing Class 2 or Class 3 circuits to be installed with certain audio circuits: “Audio system circuits described in 640.9(C) and installed using Class 2 or Class 3 wiring methods in compliance with 725.54 and 725.61 shall not be permitted to be installed in the same cable or raceway with power-limited conductors or cables.”

If it is with telephone wiring...Maybe.

Article 725.56 (D) applies if you are installing your cables in conduit along with the telephone wiring. Then, 725.56 (D) sends you to Article 800 to follow the telephone wiring rules: “Class 2 and Class 3 circuit conductors shall be permitted in the same cable with communications circuits, in which case the Class 2 and Class 3 circuits shall be classified as communications circuits and shall be installed in accordance with the requirements of Article 800. The cables shall be listed as communications cables or multipurpose cables.”

If it is with other power-limited wiring...Probably.

Jacketed cables of Class 2 or Class 3 circuits are also permitted in the same enclosure or raceway with jacketed cables of any of the following, if you follow the specific Article rules. For nonconductive and conductive optical fiber cables, comply with Article 770. For community antenna television and radio distribution systems, comply with Article 820. And for low-power, network-powered broadband communications, simply comply with Article 830.

SOME Communicator/Detector Requirements
If I am installing an alarm communicator to monitor a fire alarm installed by another company, whose responsibility is it to install a smoke detector in the room with the communicator if it is not located in the same room with the FACP? The security panel we are installing is also listed for fire, but it will only activate the siren and not the building notification appliances. —W.E. from PA.

A: Security alarm systems are not required to have a smoke/heat detector installed over the panel. The required smoke detector at the communicator must activate the building’s notification appliances and is not to be wired as a supervisory device. If the other company is agreeable, you can install the smoke detector and run its wiring back to the other company’s FACP for it to tie in. Use a four-wire smoke with an EOL relay.

However, if the firm is increasing the load of its system, the local AHJ could require a permit and submittal calculations, spec sheets, etc. If you are qualified, you could install and connect the communicator and smoke detector and take responsibility for the entire system. But that whole permit thing would still apply.

Greg Kessinger, SET, CFPS, president of an alarm installing company since 1981, teaches NICET training classes to fire alarm system designers and installers and continuing education seminars for Ohio’s fire alarm inspectors. You can reach him at 888-910-2272; e-mail: [email protected]; or visit his website at