Philips 579425 14.5T8/COR/48-840/MF21/G/DIM 25/1 15W 48" T8 MainsFit LED Ballast Bypass Lamp 4000K Cool White

Product Overview

Philips 579425 14.5T8/COR/48-840/MF21/G/DIM 25/1 15W 48" T8 MainsFit LED Ballast Bypass Lamp 4000K Cool White

The Philips 579425 (14.5T8/COR/48-840/MF21/G/DIM 25/1) is a 15W 48" T8 CorePro MainsFit LED lamp – UL Type B, ballast bypass. Unlike ballast-compatible InstantFit lamps, MainsFit lamps use a double-ended design that wires directly to 120-277V line voltage; the existing fluorescent ballast must be removed or bypassed as part of installation. Rated at 4000K cool white with 80 CRI (min), it delivers 2,100 lumens and a 50,000-hour average rated life.

Wattage

15W

48" T8

Color Temp

4000K

Cool White

Lumens

2,100

Nominal

Install Type

Type B

Ballast Bypass

Rated Life

50,000

Hours

Technical Specifications

Product Number (6nc)	579425
Model Number (12nc)	929003524804
Description Code	14.5T8/COR/48-840/MF21/G/DIM 25/1
Product Line	Philips CorePro MainsFit T8 4ft (UL Type B)
Voltage	120-277V (direct line voltage, ballast bypass)
Base	G13 Bi-Pin, double-ended
Wattage	15W
CRI (min)	80
Color Temperature	4000K (Cool White)
Nominal Lumens	2,100 lm
Beam Angle	240°
MOL (Maximum Overall Length)	48"
Lamp Material	Glass
Average Rated Life	50,000 hours (B50 L70)
DLC Product ID	S-Z5VAIG
Emergency Backup Compatibility	Compatible with the Philips PTB15D emergency driver.
Standard Package Quantity	25 per case
Mercury Content	Mercury-free (LED lamp)

Product Overview

MainsFit lamps use a double-ended design that wires both lamp ends directly to line voltage, which can simplify installation for shunted or non-shunted sockets once the ballast has been removed or bypassed – but this is a fundamentally different installation method from ballast-compatible InstantFit lamps. The existing fluorescent ballast is not used and must be disconnected as part of the retrofit; the fixture's sockets are rewired to run directly off the branch circuit.

This glass lamp delivers up to 240° beam angle with a 350° illumination angle overall, and is rated for 50,000 hours average life. Philips reports over 40% energy savings versus comparable fluorescent systems.

Compatible Applications

Retrofit installations where the ballast is being fully removed rather than kept in place
Fixtures with either shunted or non-shunted sockets (shunting of un-shunted sockets is required for proper operation – see installation instructions)
Installations requiring DLC-listed LED replacement lamps for utility rebate programs
Applications wanting emergency backup capability – compatible with the philips ptb15d emergency driver.

Before Ordering – Verify

This is a ballast bypass (UL Type B) lamp – the existing ballast must be removed and the fixture rewired for direct line voltage. This is not a plug-and-play replacement into an active ballast circuit
Installation should be performed by a qualified electrician familiar with ballast bypass wiring
Confirm socket type (shunted or non-shunted) and follow the manufacturer's installation instructions – un-shunted sockets require shunting for proper operation
Confirm lamp length (48") and wattage (15W) match your fixture

Safety and Handling Guidelines

Disconnect and lock out power before removing the ballast or rewiring the fixture – ballast bypass lamps carry direct line voltage at the lamp pins once installed
Do not attempt to install on a fixture with the original ballast still connected
Verify all wiring changes against the manufacturer's installation guide before restoring power
Turn off power to the fixture before relamping after initial installation