Replacing Christmas light bulbs and fuses

Quick picks

#	Product	Best for	Score	Price
1	Top pickWintergreen Lighting OptiCore C9 replacement bulbs, box of 25E17 base, box of 25	Keeping an existing C9 run alive	9.0★★★★★	Check price on Amazon
2	Wintergreen Lighting OptiCore C9 LED, 25 ft25 bulbs / 25 ft, 12 in spacing	Rooflines you want to keep for a decade	9.2★★★★★	Check price on Amazon
3	Novelty Lights C9 Ceramic LED, green wire25 bulbs, opaque ceramic finish	Opaque, saturated color instead of clear glass	8.5★★★★★	Check price on Amazon

#ad We may earn a commission · Prices are shown by Amazon, not by us

Scores are our own editorial judgment from published specifications and buyer feedback — not aggregated user ratings, and not from hands-on testing. See how we pick.

Jump to a full review below: lights

Replacing a bulb

On a socketed C9 or C7 set the bulb unscrews. That is the whole repair, and it is the reason socketed sets are worth buying.

1. 1

   Unplug the set

   Always, even for a single bulb. A socket with a bulb out is an exposed contact.

2. 2

   Unscrew the failed bulb

   Counter-clockwise, gently. If it is stiff from a season outdoors, grip the base rather than the lens.

3. 3

   Check the socket

   Look for green or white corrosion deposits and for water. A corroded socket will kill the next bulb too, and is the real fault behind most repeat failures.

4. 4

   Fit the matching replacement

   Match the base (E17 for C9, E12 for C7), the color, and critically the finish — faceted or smooth. Screw in until snug, not tight.

5. 5

   Never leave a socket empty

   If you have no spare, move a bulb from the least visible end of the run. An empty socket is an open path into the contacts.

Replacing a fuse

If a whole set is dark and the outlet is live, the fuse in the plug is the first suspect and it is the most common whole-set failure there is.

1. 1

   Unplug the set

   Non-negotiable.

2. 2

   Open the plug's fuse door

   There is a small sliding cover on the flat face of the plug body. It slides toward the prongs and it is usually stiff the first time. A small flat screwdriver helps.

3. 3

   Remove both fuses

   There are two tiny glass cartridge fuses. Tip them out into your hand, not onto a driveway — they are easy to lose.

4. 4

   Identify the blown one

   Hold it up to a light. A blown fuse has a broken filament or a darkened, silvered interior.

5. 5

   Fit the correct rating

   Replace with the same amp rating, which is printed on the fuse's metal end cap and usually stated on the set's tag. Spares are typically taped into the original packaging.

6. 6

   Close the door and test

   Slide the cover fully closed before plugging in.

When a fuse blows repeatedly

A fuse that blows once is a fuse. A fuse that blows twice is a symptom, and the causes are:

• Too many sets chained end to end, exceeding the limit on the tag — the commonest cause. See how many lights on one circuit.
• Water in a connection or socket, shorting the circuit.
• A damaged wire somewhere in the run.
• A wrong-voltage bulb fitted during an earlier repair.

The spares kit worth keeping

Keep these together, in the hardware bin, taped inside the lid so they are findable in December:

1. A box of replacement bulbs in the base, color and finish you run
2. A strip of spare fuses in the rating your sets use
3. A few spare clips of whatever type is on the house
4. A note of which product line each run is, so re-ordering matches

More on keeping that organized in storage ideas. If a section rather than a whole set is dark, work the diagnosis in LED Christmas lights half not working.