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Parallel ballasts use a single wire for connections to each end of a fluorescent tube. A shunted lampholder connects the lamp pins together. Generally instant start ballasts are wired in parallel.

2 and 3 Lamp Parallel Ballast Wiring

2 and 3 lamp parallel ballasts use blue wires for individual connections, and red wires for common connections. Black wire is for line voltage and white wire for neutral. A parallel ballast uses a single wire which connects from the ballast to each of the lamp terminals.

Parallel Ballast Wiring Diagrams

Parallel Ballast Wiring

2 Lamp Parallel Ballast Wiring Diagram

2 Individual wires, 1 common wire

3 Lamp Parallel Ballast Wiring Diagram (2 Ballasts)

One 2 lamp and one 1 lamp ballast

4 Lamp Parallel Ballast Wiring Diagram

4 Individual wires, 2 common wires

4 lamp parallel ballasts and 2 lamp series ballasts use blue and red wires for individual connections, and yellow wires for common connections.

A parallel ballast uses a single wire connecting the ballast to each of the lamp terminals.
A series ballast uses two wires connecting the ballast to each of the lamp terminals.

3 Lamp Parallel Ballast Wiring Diagram

3 Individual wires, 1 common wire

Fluorescent Ballasts

Ballast Wiring

Parallel Ballast Wiring

Series Ballast Wiring 1 to 3 Lamps

Series Ballast Wiring 4 Lamps

Dimming Ballast Wiring

CFL Ballast Wiring

Emergency Ballasts

Fluorescent Lampholders

Fluorescent Lampholder Wiring

Parallel Ballast Lampholder Wiring

Series Ballast Lampholder Wiring 2 and 4 Lamps

Series Ballast Lampholder Wiring 3 Lamps

Swap Terminals on Non-Shunted Lampholders