Primary Supply Circuits and Dedicated Branch Circuits.

The type of receptacle used does not dictate whether the circuit is considered an “individual branch circuit”.
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The type of receptacle used does not dictate whether the circuit is considered an “individual branch circuit”.

Since Section 4.4.2.1 in NFPA 731 requires the primary power supply for a security system to be either a dedicated branch circuit, or the unswitched portion of a specific branch circuit if not using a dedicated branch circuit, it is important to understand what is considered a dedicated branch circuit.

Neither NFPA 731 or the NEC® has a definition of a “dedicated branch circuit” but the NEC® does have the following definition of an “individual branch circuit”:

NEC Article 100: Branch Circuit, Individual. A branch circuit that supplies only one utilization equipment.

Since an individual branch circuit supplies “only one utilization equipment”, many have interpreted this definition to mean that if a dedicated branch circuit supplies a receptacle, the receptacle must be a single type receptacle like receptacle “A” in the image. This is incorrect.

The truth is, as long as the security system is the only utilization equipment plugged into the receptacle and served by the branch circuit, then receptacle “B” in the image is also code compliant.

The NEC® Article 100 definition of an individual branch circuit does not require the receptacle itself to be of the single type. It just describes the individual branch circuit as serving “only one utilization equipment”.

Below is a sample of the NEC®. See the actual NEC® text at NFPA.ORG for the complete code section. Once there, click on their link to free access to the latest NEC® edition of NFPA 70.

Article 100 Definitions.

Branch Circuit, Individual. A branch circuit that supplies only one utilization equipment.

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Primary Supply Circuits and Dedicated Branch Circuits.

Below is a Real Question from our Electrical Continuing Education Courses for Electrical License Renewal:

Refer to the image:

Which of the following is true?

A: Only receptacle type A can be used to supply a security system.
B: Only receptacle type B can be used to supply a security system.
C: As long as the security system is the only utilization equipment plugged into the receptacle and served by the branch circuit, then receptacle “B” in the image is code compliant.
D: Receptacle type A is described in the NFPA 731 definition of a “dedicated branch circuit”.
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