How to do a low voltage takeoff

Read the spec first

Division 27 covers communications: structured cabling, audio and video. Division 28 covers electronic safety and security: access control, cameras, intrusion and fire alarm. Read each section that applies. Note the cable category, the makers and the testing rules. Note any certification the installer must hold.

Sheets and schedules that carry the count

• The technology sheets. They show outlets, wireless access points and devices.
• The symbol legend. It states how many cables each outlet symbol needs.
• The riser diagrams. They show backbone cable between rooms.
• The rack elevations and the telecom room layouts.
• The security plans. They show cameras, card readers and door contacts.
• The door hardware schedule. It shows the doors with electrified hardware.
• The electrical sheets, for conduit, boxes and cable tray.

Steps in order

1. Read the legend. Record the cable count for each symbol.
2. Count outlets and devices by symbol, one floor at a time.
3. Assign each device to its telecom room.
4. Work out the cable length. Use a measured run or an average for each room.
5. Measure backbone cable from the riser diagram.
6. Count racks, patch panels, cable managers and ground bars.
7. Count cameras, readers, panels and power supplies.
8. Add terminations, labels, testing and firestopping.

Count, length, area or volume

• Count: outlets, jacks, devices, racks, patch panels and terminations.
• Length: horizontal cable, backbone cable, cable tray and conduit.
• Area: seldom used. Some estimators check wireless coverage by area.
• Volume: none.

Conflicts to find, and what to exclude

• The legend states one cable category. The spec states another.
• The technology sheets and the furniture plan show different outlet counts.
• The door hardware schedule has card reader doors that the security plan omits.
• Nobody states who installs conduit, boxes and cable tray.
• The drawings show switches and servers. The spec says the owner furnishes them.

State if raceway is by the electrician. Exclude active network equipment, software licenses and line voltage power unless the documents give them to you. Qualify programming and owner training. State if fire alarm is in your number.

Trade takeoffs · Updated 11 Nov 2026