Circle PLC-18W 4 Pin CFL Bulb, 2700K, 4 Pack Review

Circle sells this pack to solve a specific identification problem that trips up a lot of CFL replacements: the same physical bulb is sold under several different brand names, Philips PL-C, Sylvania CF18DD/E, GE F18DBX, Osram Dulux D/E and others, which can make finding a replacement confusing if the old bulb is from a different maker than the fixture label suggests.

The listing is specific about what this bulb is and is not: an 18 watt, 4 pin, G24q-2 base compact fluorescent, about 6.1 inches overall, running on the electronic ballast already built into the fixture with no rewiring required. It explicitly rules out the 13W G24q-1, 26W GX24q-3, 2-pin G24d and LED variants that look superficially similar but are not interchangeable.

Color temperature is 2700K, described as warm white, at 82 CRI, which Circle positions for hotel rooms, living areas, sconces, and table and floor lamps, aiming for the same warm tone as an incandescent bulb rather than a cooler white light.

Each bulb is a T4 double tube, 4 pin design on a G24q-2 base, and Circle is explicit that counting the pins on the old bulb, 4 pins and about 6.1 inches overall, is the quickest way to confirm this is the correct replacement before ordering. It runs on an existing electronic ballast rather than needing a ballast bypass or rewiring, which keeps installation to a simple bulb swap.

The 827 code in the model naming refers specifically to the 2700 Kelvin, 80-plus CRI combination, which Circle translates directly into the same warm, inviting tone as an incandescent bulb. That consistency in naming convention across the CFL double tube category is useful context since the same 827 code appears on the Philips, Sylvania and GE equivalents this bulb is built to replace.

Lifetime is rated at 10,000 hours, but Circle is specific that figure assumes a 3-hour on, 20-minute off duty cycle, the standard way CFL life is measured. In short cycle environments like a bathroom exhaust fan light that gets switched on and off frequently, Circle states to expect fewer hours than the full rating, while all-day office, corridor or downlight duty should see the full rated life.

The bulb is not dimmable on a standard ballast and is rated for indoor, dry locations only, both real constraints worth checking against the fixture's intended use before installing.

The direct replacement list is the most practically useful performance detail here: Circle names specific part numbers, Philips PL-C 18W/827/4P, Sylvania CF18DD/E/827, GE F18DBX/827/ECO4P, Osram Dulux D/E 18W/827, Sunlite PLD18/E/SP27K, Satco S6734 and Panasonic FDS18E35/4, as equivalents. That level of cross reference specificity is more useful for sourcing a correct replacement than a vague compatible with most fixtures claim.

At 2700K and 82 CRI, the color output should read close to an incandescent bulb's warmth, which matters for maintaining consistent lighting in hotel rooms, living areas and lamp settings where a cooler toned CFL would stand out against existing warm white fixtures.

The 10,000 hour rating comes with an honest caveat about duty cycle rather than being presented as a flat guarantee: frequent short on off cycles, as in a motion activated or exhaust fan light, will shorten real world life below the rated figure, while continuous or long duration use, as in office or corridor downlights, should reach the full rating.

Fitting Panasonic WhisperLite fan lights and similar fixtures that take an 18W 4-pin double tube is named specifically, which is a useful data point for anyone replacing a bulb in that exact fixture type.