Section 3-1 - Control Panel Installation
 
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Current Draw Calculations

A battery calculation worksheet must be completed to ensure that the desired amount of standby is possible for the battery intended to be used with the 5208.

Manual calculations can be performed using Table 3-2 found in the 5208 Installation Manual (P/N 151204) page 3-6. Click here to download a PDF version that you can open up in Adobe Acrobat Reader and print.

Automatic calculations can be done using the Silent Knight 5208 battery calculation Microsoft Excel Worksheet. Click here to download the XLS file.

Filling in the Manual Current Draw Worksheet

The following steps must be taken when filling in the manual current draw worksheet to determine the SK-5208 current draw and standby battery requirements.

  1. For the SK-5208, the worst case current draw is listed for the panel and panel accessories. Fill in the number of devices that will be used in the system and compute the current draw requirements for alarm and standby. Record this information in Table 3-2 at Line A.
  2. Add up the current draw for all smoke detectors and record in the table at Line B.
  3. Add up all notification appliance loads and record in the table at Line C.
  4. For notification appliances and auxiliary devices not mentioned in the manual, refer to the device manual for the current ratings.
  5. Make sure that the total alarm current you calculated, including current for the panel itself, does not exceed 6.0A. This is the maximum alarm current for the SK-5208 control panel.

    If the current is above 6.0A you will need to use a notification power expander(s) such as the Silent Knight 5495 to distribute the power loads so that the SK-5208 or the power expanders do not exceed their power rating. Refer to the current draw worksheets provided with the 5495 manuals so you do not exceed their power requirements.
  6. Complete the remaining instructions in Table 3-2 for determining battery size requirements.

Sample Battery Calculation Worksheet Table 3-2

A
Device
Number of Devices
Current per Device
Standby Current
Alarm Current
For each device use this formula:
This column x
This column =
Current per number of devices.
SK-5208 Fire Panel (Current draw from battery)
1
 Standby:
140mA
140mA
Alarm:
460mA
460mA
Panel Accessories
SK-5217 Zone Expander (2 max.)
Standby:
60mA
mA
Alarm:
260mA
mA
5220 Direct Connect Module Standby:
15mA
mA
Alarm:
15mA
mA
SK-5235 Remote Annunciator (6 max.) Standby:
30mA
mA
Alarm:
50mA
mA
SK-5280 (8 max.) Relay Standby:
10mA
mA
Relay Alarm:
80mA
mA
Outputs Max. Standby:
0mA
0mA
Max Alarm Per Output:
100 mA
mA
Max. Alarm for all Outputs per 5280: 700 mA
7181 Fire Zone Converter
Standby:
35 mA
mA
Alarm:
65 mA
mA
Total System Current
mA
mA
B
Smoke Detectors
Refer to device manual for current ratings.
Standby:
mA
mA
Alarm:
mA
mA
Standby:
mA
mA
Alarm:
mA
mA
Standby:
mA
mA
Alarm:
mA
mA
Standby:
mA
mA
Alarm:
mA
mA
Smoke Detector Current
mA
mA
C
 Notification Appliances
Refer to device manual for current ratings.
Alarm:
mA
0 mA
mA
Alarm:
mA
0 mA
mA
Alarm:
mA
0 mA
mA
Alarm:
mA
0 mA
mA
Notification Appliances Current
0 mA
mA
D Additional Devices
Standby:
mA
mA
Alarm:
mA
mA
Standby:
mA
mA
Alarm:
mA
mA
Additional Device Current
mA
mA
E
 Total current ratings of all devices in system (line A + line B + line C + Line D)
mA
mA
F
 Total current ratings converted to amperes (line E x .001):
A
A
G
 Number of standby hours (24 or 60 for NFPA 72, Chapter 1, 1-5.2.5).
H
H
 Multiply lines F and G.
Total standby AH
AH
I
 Alarm sounding period in hours. (For example, 5 minutes = .0833 hours.)
H
J
 Multiply line F and I.
Total alarm AH
AH
K
 Add lines H and J.
(Use next size battery with capacity greater than required.)
Total standby and alarm AH
AH


 
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