Calculators
PoE budget, CCTV storage, pixel density, fire alarm batteries, PA amplifiers, fibre loss, and voice bandwidth.
Open calculators →Checklists
12 printable checklists for surveys, commissioning, maintenance, and safety.
Browse checklists →Quick reference
14 cards: pin-outs, colour codes, PoE classes, SIP codes, fire alarm figures, and more.
View cards →Field tips
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CCTV
1 Mbps recorded continuously uses about 10.8 GB per day. Multiply by the bitrate, cameras, and retention days.
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CCTV
Take a baseline snapshot of every camera view at handover. It makes moved or obstructed cameras obvious later.
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Fire alarm
Fit the end-of-line resistor at the last device, never at the panel, or the circuit is not supervised.
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CCTV
Check every camera at night as well as during the day. IR reflection and focus shift only show up in the dark.
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Analog CCTV
CCTV coax is 75 Ω (RG59/RG6). RG58 is 50 Ω and causes ghosting.
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PBX
Calls dropping at about 32 seconds? The ACK is not getting through. Check NAT and firewall rules.