Low Voltage Scope of Work: Div 27 Cabling, AV, and Pathway Scope Splits for Commercial GCs
What to put in a low voltage scope of work — Cat 6A/fiber structured cabling, AV scope boundaries, pathway and raceway by electrical, and the BICSI certification deliverables.
Low voltage systems are among the most frequently fragmented scopes in commercial construction. Structured cabling, audio-visual, access control, security cameras, nurse call, distributed antenna systems (DAS), and building automation interfaces all fall under the "low voltage" umbrella — but each is typically contracted and installed by a different specialty sub. Without a clear low voltage scope of work that defines the scope boundary of each system and assigns responsibility for conduit, backboxes, and pathway, you will have overlapping claims and uncovered work at substantial completion. This guide covers the key systems, package requirements, and coordination checkpoints.
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Div 27 Systems, Cabling Standards, and Sub-Trade Boundaries
The scope boundary between Div 27 low voltage, Div 26 electrical, Div 28 security, and owner-direct AV integrators must be drawn explicitly — system by system — before any sub is awarded.
Low voltage scope must define each system type, the scope boundary with the electrical sub, and the specific deliverables for each specialty sub.
Structured Cabling (Voice and Data)
Category rating: Specify Cat 6 (1 Gbps to 100m), Cat 6A (10 Gbps to 100m) or Cat 8 (40 Gbps, short-run data center applications) per TIA-568.2-D. Cat 6A is the current commercial standard for new office and institutional construction. Cat 5e is obsolete for new commercial installations.
Horizontal cabling: From the telecom room (TR) to each work area outlet. Specify maximum run length (100m per TIA-568), cable route (cable tray, J-hooks, or conduit), and the number of ports per workstation location. Define who provides the cable tray vs. the low voltage sub.
Telecommunications rooms (TR/MDF/IDF): Specify TR dimensions, equipment racks (42U, 45U open frame or enclosed), patch panels (24-port or 48-port), and cable management. Grounding and bonding per TIA-607-C must be specified and connected to the electrical grounding system — define whether this is the electrical sub's scope or the low voltage sub's scope.
Fiber optic backbone: Between TRs and the main distribution frame (MDF). Specify fiber type (OM4 multimode for campus backbones, OS2 single-mode for extended campus or inter-building runs), connector type (LC, SC, or MPO for multi-fiber), and minimum bend radius requirements.
Audio-Visual (AV) Systems
Specify AV system type per room: conference room display system (LED display, projection), video conferencing (integrated camera/mic/speaker), digital signage, auditorium or boardroom AV (distributed audio, programmable control), and lobby/common area displays.
Define the AV scope boundary: many projects have a separate AV integrator who is owner-direct. In this case, the low voltage sub's scope may be limited to conduit, backboxes, and pull strings — the AV integrator installs cables and equipment. Define this explicitly to avoid duplicated scope.
HDMI, DisplayPort, and USB-C wall plates must be specified at each room location, including routing for cable management and sufficient box depth for multi-port keystones.
Security and Access Control
Access control: Card readers, door controllers, and electric strikes or magnetic lock hardware. Specify card reader technology (proximity, smart card, mobile credential), controller panel location, and software platform. The access control system integrates with the electrical sub (for mag-lock power and door position switches) and the door hardware sub — define each interface. (See security systems scope for the full Div 28 package.)
CCTV / IP camera system: Specify camera resolution (minimum 4MP for commercial), camera type (fixed dome, PTZ, fisheye), indoor vs. outdoor rating (IP66 for exterior), mounting location, and network video recorder (NVR) or video management system (VMS) platform.
Intrusion detection: Motion detectors, door/window contacts, glass break sensors, and central monitoring panel. Specify zones, monitoring service provider interface, and UL listing if monitored response time is required by insurance.
Other Low Voltage Systems
Distributed Antenna System (DAS): Required in large commercial buildings (typically over 50,000 sf) where cellular coverage is inadequate. DAS scope requires coordination with the cell carrier representatives before design. This is a specialty sub that requires early engagement.
Nurse call / emergency call: For healthcare, assisted living, and some institutional occupancies. Specify system manufacturer, call station types, and integration with the facility's paging and nurse station systems.
Fire alarm interface: Low voltage subs do not typically install fire alarm systems (this is a licensed fire protection sub), but low voltage conduit often conflicts with fire alarm conduit above ceilings. Define who installs conduit for each system and how above-ceiling real estate is allocated.
Tip for PMs: The most common low voltage scope gap is conduit and backbox provision for owner-furnished or owner-direct technology systems (AV integrators, security vendors, telecom carriers). The GC scope typically includes conduit and rough-in, but this is often not communicated to the low voltage sub. Require a consolidated conduit routing plan from all low voltage specialty subs before rough-in begins.
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Common Low Voltage Scope Gaps at Buy-Out
Items routinely missing from low voltage bids — cable tray, backboxes, certification testing, rack elevations, and PoE switch infrastructure — that drive scope disputes and uncomparable bids.
Low voltage submittals must include system architecture drawings, not just product data sheets. Without a rack elevation and cable routing plan, above-ceiling installation will be chaotic.
Required Submittals
System architecture drawing for each low voltage system: floor plan showing device locations, cable routes, and TR/MDF locations
Product data sheets for all passive and active components (patch panels, switches, cameras, controllers, access readers)
TIA-568 compliance testing plan: specify that all horizontal cabling will be field-tested with a Fluke DSX or equivalent certifier to TIA Category performance levels; test reports to be provided as a project closeout deliverable
Cable schedule: cable ID, origin, destination, and termination point for all runs
Warranty and Certification
Specify the manufacturer's system warranty for structured cabling: most major manufacturers (Belden, CommScope, Panduit, Leviton) offer a 25-year application assurance warranty when installed by a certified contractor using the manufacturer's complete system (cable, connectors, patch panels). Require the installer to be a certified contractor under the manufacturer's program.
For AV systems, specify a minimum 1-year parts and labor warranty from the AV integrator or sub, and define the service response time for system failures.
Best Practices from Leading GCs
Hold a single above-ceiling coordination meeting with all low voltage subs, the HVAC sub, the electrical sub, and the fire protection sub before rough-in begins. Low voltage cable tray and conduit compete for the same above-ceiling space as mechanical ductwork and electrical conduit — resolve conflicts in 2D or BIM before anyone starts pulling cable.
Require a consolidated low voltage outlet schedule that maps every room and shows exactly which systems have a device in that room. This prevents installation of cable without a backbox and discovery of missed outlets during punchlist.
Define the testing and turnover process: all structured cabling must be certified and test reports submitted before AV and IT equipment is installed. Troubleshooting cable failures after equipment is connected is extremely difficult.
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Low Voltage Coordination with Electrical, IT, and AV
Interface items between the low voltage sub, the electrical sub providing pathway and power, the AV integrator, and the owner's IT team — all of which must be defined before rough-in.
Low voltage coordinates with the electrical sub (power for active devices), the AV integrator, and the owner's IT team. All three handoffs must be defined explicitly.
Electrical Sub Coordination
Power over Ethernet (PoE) devices (IP cameras, access readers, VoIP phones, wireless access points) are powered through the network switch, not through a separate power circuit. The electrical sub does not need to provide power at each device location — confirm this with both subs to avoid duplicated scope.
Dedicated circuits for network equipment in TRs must be provided by the electrical sub (typically 20A dedicated circuits for each equipment rack). Define the number and location of circuits in the electrical scope — this is frequently missed.
Grounding and bonding of the telecom room per TIA-607-C: the electrical sub provides the bonding conductor from the service entrance; the low voltage sub installs the grounding bar and bonds all racks and cable tray.
Owner and IT Coordination
Require the owner's IT team to provide wireless access point locations and counts before rough-in. WAPs require a Cat 6A home-run cable and a ceiling backbox — late WAP location changes are expensive to re-route in finished ceilings.
Confirm the network switch platform (Cisco, Aruba, Meraki) and any owner-furnished active equipment before the TR rack layout is finalized. Owner-furnished equipment dimensions must match the rack design.
Pre-Installation Coordination Checklist
Consolidated low voltage outlet schedule issued and reviewed by all low voltage subs
TR dimensions, power circuits, and grounding confirmed with electrical sub
WAP locations confirmed with owner's IT team
AV scope boundary defined — conduit only vs. complete AV installation
Owner-furnished equipment list confirmed for rack design
Cable certification testing plan submitted and approved
Tip for Estimators: When reviewing a low voltage bid, check whether cable tray, conduit, and backboxes are included or whether the sub is pricing "direct cable only." In most commercial projects, the above-ceiling cable tray and conduit stub-outs represent 25–35% of the low voltage rough-in cost. A bid without these items is not comparable to a complete price.
Low Voltage Scope of Work — FAQ
Cat 6 or Cat 6A — what should I specify for new commercial construction?
Cat 6A is the current commercial standard for new office, institutional, and healthcare construction. It supports 10 Gbps to 100 m and provides the headroom for future PoE++ (90W) device loads. Cat 6 is acceptable for tenant fit-outs in older buildings where the existing backbone limits performance, but specifying Cat 6 in new construction creates a re-cable risk within the building's useful life. Cat 5e is obsolete for new commercial work.
Who provides pathway and raceway — Div 26 electrical or Div 27 low voltage?
The default in most commercial specs is: the electrical sub provides primary pathway (cable tray, conduit through fire-rated assemblies, sleeves through floor slabs); the low voltage sub provides J-hooks, fly cable supports, and termination backboxes. The scope must state this explicitly — pathway scope gaps are the single largest source of low voltage change orders. Define cable tray ownership room by room if necessary.
Who terminates and certifies the structured cabling?
The low voltage sub terminates and certifies all horizontal cabling using a Fluke DSX or equivalent Level IV/V field tester to TIA-568 Category performance limits. Certification reports (per-cable test results) are a project closeout deliverable, not an option. Require BICSI-certified RCDD oversight on installations over 200 drops, and require the installer to be a manufacturer-certified contractor if the owner wants the 25-year application assurance warranty (Belden, CommScope, Panduit, Leviton).
How do I scope AV when there is an owner-direct AV integrator?
State explicitly that the low voltage sub provides conduit, backboxes, pull strings, and 120V power at each AV location; the owner-direct AV integrator supplies and installs all AV cabling, displays, and active equipment. Include a coordination requirement: the AV integrator must publish a backbox and conduit schedule by a defined date, and the low voltage sub must rough in to that schedule. Without this, the GC absorbs the cost of every late-discovered AV outlet.
Who provides the PoE switches for IP cameras and access readers?
This is a recurring scope-gap question. On projects with a single low voltage sub responsible for both data and security, the switches are typically in that sub's scope. On projects with a separate security sub (Div 28) and a separate low voltage sub (Div 27), the PoE switches frequently fall in a grey zone. Assign them in writing to one sub — usually the security sub for security-only PoE switches, or the low voltage sub for general-purpose PoE infrastructure shared with data and WAPs.
What lead time should I assume for structured cabling materials?
Cat 6A cable, patch panels, and connectors are typically 4–8 weeks for major manufacturers; longer for less common configurations (plenum-rated low-smoke variants, armored cable). Active equipment (switches, NVRs, WAPs) is 8–16 weeks depending on vendor and chip availability. Issue NTP for material procurement well before above-ceiling rough-in begins — late cable delivery is one of the most common low voltage schedule disruptions.
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