How to Replace 4ft Fluorescent Tubes with LED (F32T8, F40T12)

The 4 foot fluorescent tube is the most common lamp in commercial buildings. Swapping it for a 4ft T8 LED tube cuts the wattage roughly in half. The only real decision is how you wire it.

What replaces what

All 4ft T8 LED tubes use the same G13 bi-pin base as the fluorescent lamp, so they drop into the existing sockets. T12 fixtures have the same socket spacing, which is why an old T12 fixture can take a T8 LED tube once the T12 ballast is bypassed.

Pick the wiring type

• Type A, plug and play. Runs on the existing T8 electronic ballast. Fastest install, but the ballast stays and will eventually fail. Check the ballast compatibility list.
• Type B, ballast bypass. Ballast comes out, line voltage goes to the sockets. Most efficient and nothing left to fail. Required for T12 fixtures, since T12 magnetic ballasts do not run LED tubes.
• Type A+B, hybrid. Works on the ballast now and direct wire later. Good when you cannot rewire a whole building at once.

The full breakdown, including the shunted socket trap, is in LED tube types explained.

Color temperature and lens

4000K is the safe choice for offices, schools and retail. 5000K reads crisper for warehouses, shops and garages. 6500K is very blue and best kept to spaces where people expect it. A frosted lens hides the LED dots and cuts glare, and a clear lens gives a little more output for high ceilings or covered fixtures.

Converting 8 foot fixtures too? Read how to replace 8ft fluorescent tubes with LED.