Gentex GN-503 Combination Photoelectric Smoke and Carbon Monoxide Alarm, 120VAC, 9V Battery Backup, Interconnectable

Gentex GN-503 — 120 VAC combination photoelectric smoke and carbon monoxide alarm with 9 V battery back-up, single or multiple station.

An infrared LED sensing circuit pulses every 4 to 5 seconds and the alarm sounds after two consecutive pulses in smoke, while a separate electrochemical cell watches for carbon monoxide; smoke takes priority when both are present. DUALINK tandem wiring links the unit to other Gentex tandem-capable alarms.

• 120 VAC 60 Hz, 0.045 A, 9 V alkaline back-up (Duracell MN 1604)
• Nominal smoke sensitivity 2.5%; CO not detected below 30 PPM
• Temporal 3 for smoke, temporal 4 for CO; 85 dBA at 10 ft
• ANSI/UL 217 and ANSI/UL 2034 certified; CSFM 7263-0569:0500
• Up to 18 devices in tandem, at most 12 of them smoke alarms
• 6.25 in diameter, 1.80 in deep; 40 to 100 °F

The plain GN-503 has no relay: GN-503F adds one set of Form A and Form C contacts, GN-503FF two sets that operate independently. Gentex lists the GN-503 Series as discontinued; the matching relay-free 120 VAC smoke and CO alarm in the current line is the SC (918-0031-002), on a smaller 5.5 in body.

Documents

• GN-503 Series Combination Smoke & CO Alarm — Data Sheet (PDF)
• GN-503 Series Installation and Operation Manual (PDF)

FAQ

Can the GN-503 interconnect with other brands?
No. It uses DUALINK tandem wiring with Gentex tandem-capable alarms only; Gentex alarms cannot be interconnected with alarms from other manufacturers.

How many alarms can be connected together?
Up to 18 compatible smoke, heat, CO and combination alarms, with no more than 12 of them smoke alarms, and no more than 125 ft between alarms.

Does the GN-503 have relay contacts?
No. The GN-503F adds one set of Form A/Form C contacts and the GN-503FF two sets that operate independently for smoke and CO.

What replaces the GN-503?
The GN-503 is discontinued; the replacement is the Gentex SC (918-0031-002).