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Electricalaka: LVaka: Class 2 wiringaka: signal wiring

Low Voltage

In Plain English

Electrical systems running at 50 volts or less, used for things like data cables, door bells, and security cameras.

Definition

Electrical systems operating at 50 volts or less, commonly used for data, communications, fire alarm, security, lighting controls, and audiovisual systems. Low-voltage wiring is typically installed by specialty contractors and governed by NEC Article 725 and related articles. These systems require less stringent conduit and wiring methods than line-voltage systems.

Why It Matters in Bidding

Low-voltage scope frequently falls into a gray zone between the electrical sub, the technology sub, and owner-furnished vendors, so estimators must pin down exactly who carries data, fire alarm, security, and AV in the bid. Mis-assigned low-voltage work is a leading source of bid-day gaps and post-award change orders because pathways, backboxes, and conduit stub-ups often live in different specification divisions.

Example

During takeoff, the estimator flags that fire alarm devices are spec'd under Division 28 but the conduit and backboxes are in Division 26, so she carries the rough-in with the electrical sub and excludes the head-end to avoid double-counting.

Related Terms

NEC (National Electrical Code)ConduitCircuitConductor

Frequently Asked Questions

It varies by project and must be confirmed against the specification divisions and scope sheets. Often the electrical sub carries pathways, backboxes, and power, while specialty subs handle data, fire alarm, security, and AV devices and programming. Clarifying these splits before bid day prevents both gaps and double-counting that erode margin.
Because systems at or below 50 volts qualify for relaxed installation methods, cabling can often run without rigid conduit using plenum-rated cable, J-hooks, and cable tray. Reduced raceway, smaller crews, and faster pulls lower labor and material costs, though estimators should still verify whether local codes or the spec mandate conduit in certain areas.
Yes. Breaking low-voltage out from line-voltage power gives clearer scope ownership, simplifies comparing specialty sub quotes, and isolates owner-furnished versus contractor-furnished systems. A discrete line item also makes addenda and change-order pricing cleaner when device counts, head-end equipment, or programming requirements shift during the project.

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