System Sensor S1224MC Wire Sizes, A Current Draw Measurements RMS, B Horn Sound Measurements dBA

Wire Sizes

The designer must be sure that the last device on the circuit has sufficient voltage to operate the device within its rated voltage. When calculating the voltage available to the last device, it is nec- essary to consider the voltage drop due to the resistance of the wire. The thicker the wire, the less the voltage drop. Generally, for purposes of determining the wire size necessary for the system, it is best to consider all of the devices as “lumped” on the end of the supply circuit (simulates “worst case”).

Typical wire size resistance:

18 AWG solid:	Approximately 8 ohms/1,000 ft.
16 AWG solid:	Approximately 5 ohms/1,000 ft.
14 AWG solid:	Approximately 3 ohms/1,000 ft.
12 AWG solid:	Approximately 2 ohms/1,000 ft.

Example: Assume you have 10 devices on a zone and each re- quires 50 mA average and 2000 Ft. of 14 AWG wiring (total length=outgoing +return). The voltage at the end of the loop is 0.050 amps per device x 10 devices x 3 ohms/1,000 ft. x 2000 ft =3 volts drop.

NOTE: If class “A” wiring is installed, the wire length may be up to 4 times the single wire length in this calculation.

The same number of devices using 12 AWG wire will produce only 2 volts drop. The same devices using 18 AWG wire will produce 8 volts drop. Consult your panel manufacturer’s specifications, as well as SpectrAlert’s operating voltage range to determine accept- able voltage drop.

Figure 1A: Current Draw Measurements (RMS)

NOTE: All ‘S’ and ‘P’ models were only tested at the 8-17.5 and 16-33 Volt-FWR/DC limits. This does not include the 80% low- end or 110% high-end voltage limits.

	Strobe Current Draw
	FWR	DC
	Operating	Operating
	Current	Current
Candela	Strobe	Strobe
Setting	12V 24V	12V 24V

15112 64 127 59

15/75	135	74	127	69
30		93		90
75		158		160
110		208		209

Figure 1B: Horn Sound Measurements (dBA):

Selectable Horn Tones			8-17.5V	16-33V
Temporal	Low	Electromechanical	67	75
	Volume
		3000 Hz Interrupted	68	75
	High	Electromechanical	71	80
	Volume
		3000 Hz Interrupted	72	81
Non-	Low	Electromechanical	71	79
Temporal	Volume
		3000 Hz Interrupted	72	79
	High	Electromechanical	76	84
	Volume
		3000 Hz Interrupted	77	86

Figure 1C: Horn Current Draw Measurements (RMS):

				DC			FWR
Selectable Horn Tones
			12V		24V	12V		24V
Temporal	Low	Electromechanical	15		23	13		23
	Volume
		3000 Hz Interrupted	15		33	13		23
	High	Electromechanical	36		53	20		44
	Volume
		3000 Hz Interrupted	43		57	21		40
Non-	Low	Electromechanical	16		37	19		29
Temporal	Volume
		3000 Hz Interrupted	16		32	18		33
	High	Electromechanical	38		49	46		49
	Volume
		3000 Hz Interrupted	44		56	42		58

NOTE: Regulated 12 VDC, max operating current 44.4 mA Regulated 24 VDC, max operating current 57.0 mA 12 V FWR, max operating current 45.7 mA

24 V FWR, max operating current 57.5 mA

NOTE: 12VDC 2-wire horn/strobe current is shown in Figure 1D. 24VDC 2-wire horn/strobe current is shown in Figure 1E. Current draw for other horn/strobe power supplies can be calculated by adding the strobe current draw (Figure 1A) for chosen candela set- ting to the horn current draw (Figure 1C) for chosen setting.

Figure 1D: 12VDC Horn/Strobe Current Draw Measurements (mA RMS)

		Temporal
	Low Volume		High Volume
Candela	Electromechanical	3000 Hz	Electromechanical	3000 Hz
Setting
15	111	111	112	112
15/75	127	127	126	129
		Non-Temporal
15	113	112	114	115
15/75	128	128	130	134

Figure 1E: 24VDC Horn/Strobe Current Draw Measurements (mA RMS)

		Temporal
	Low Volume		High Volume
Candela	Electromechanical	3000 Hz	Electromechanical	3000 Hz
Setting
15	71	70	73	75
15/75	86	85	87	88
30	99	98	100	100
75	166	166	167	170
110	209	209	210	213
		Non-Temporal
15	74	74	79	82
15/75	86	88	93	96
30	101	101	107	110
75	167	167	173	176
110	213	213	218	222

D900-28-00 2 I56-1796-011R