The best trimmable Christmas lights

The only genuinely trimmable Christmas light: continuous SPT-1 socket wire on a spool with no plugs fitted, so every run is cut to the length of the actual run and terminated by you.

This is what trimmable actually means in Christmas lighting, and it is a format rather than a feature on a box. A spool is continuous socket wire with no plug on either end. HolidayLEDs sells it in 100 ft and 1000 ft lengths and states plainly that the C9 SPT-1 socket spools are there to allow custom light strings. You measure the gutter, cut the wire between two sockets, fit a plug, and the run is the length of the gutter.

Christmas Light Source is explicit about which lights can be treated this way: C7, C9 and E26 medium-base cords with 20, 18, 16 or 14 AWG lamp cord wiring can be cut to custom lengths and terminated. Mini lights cannot, because their small wiring harnesses are wired in series — cutting one is how you get a dead strand rather than a shorter one.

The practical reason to do this is the thing that annoys people most about retail sets: the last set on a run is always the wrong length. You either stop three feet short of the corner or you have a loop of slack zip-tied behind the downspout. On a spool there is no last set. There is one run, cut where the gutter ends.

Be honest about the part the product photos leave out. You are fitting the plugs. That means a wire cutter, the right SPT-1 zip plugs, and attention to which conductor is which — Christmas Light Source's own advice is to consult a master electrician if you have questions and to check your work. If that sentence makes you uneasy, buy sets. If you have rewired a lamp, this is easier than that.

Cost is the other half of the case. Per foot, spool plus bulbs plus plugs lands under the equivalent length in retail 25 ft sets, and the gap widens the longer the roofline. Under roughly 50 ft of roof it is not worth the learning curve. Over roughly 100 ft it is the obvious answer, and it is how professional installers buy.

The small part that makes a spool usable. Slide-on SPT-1 plugs pierce the zip cord as they close, so a cut end becomes a finished end with a pair of pliers and no stripping.

If you cut socket wire you have created two unfinished ends, and the plug is how you finish them. The slide-on SPT-1 plug — sold as a Gilbert plug or a vampire plug — has two internal blades. You push the zip cord in, squeeze the body shut with pliers, and the blades pierce the insulation to make contact. There is no stripping and there are no screws.

Christmas Light Source's guidance on cut cords is to choose a proper plug, and to deal with the other end either by fitting a female plug or by closing it off with electrical tape or liquid electrical tape. A female plug is the better call in almost every case, because it means next December you can add a run to the end rather than pulling the whole thing down.

The one specification that matters is the wire type, and it is the one people get wrong. SPT-1 and SPT-2 describe the insulation thickness of the zip cord. An SPT-1 plug on SPT-2 wire will not close correctly, and the fix is buying the right plugs rather than forcing it. Check the spool listing for which it is before ordering, and buy a few more plugs than you need.

Order these with the spool, not after it. The most common way this project stalls is a roofline of cut socket wire sitting in the garage in the second week of December because the plugs are three days out.

The reason to own socket-based C9 in the first place. A box of 25 E17 bulbs turns a dead spot on the roof into a five-minute fix instead of a re-install.

Buy a box of these at the same time you buy the lights. That is the whole recommendation.

The E17 base is a genuine standard, so a Wintergreen bulb will screw into another brand's C9 socket. That matters in year four, when the set you originally bought has been discontinued and you have one dark bulb over the garage.

Match the finish, though. Faceted bulbs have a cut-glass texture that catches light; smooth or ceramic bulbs are opaque. Put one faceted bulb in a run of twenty-four smooth ones and it is the only thing anyone sees.

If your lights are molded mini strings rather than socketed C9, none of this applies and there is nothing to replace. That difference is the strongest practical argument for socketed C9 over cheap strings, and it only shows up after a couple of seasons.

The permanent-lighting model explicitly designed to be cut and reconnected, which is what lets it fit a roof with gables and returns instead of forcing the roof to fit the kit.

Permanent lighting and trimmable lighting overlap at exactly one point: a track you mount once has to match the roofline exactly, because you will be looking at it in July. Govee's Pro models are the ones specified for that. Govee describes the 2 Pro as designed to be cut, extended or reconnected to fit different eave lengths and complex rooflines, and sells it as 100 ft and 200 ft kits with a 200 ft total cap once extensions are added.

The model naming is the trap here and it is worth spelling out. Govee's permanent range contains models that are cuttable and models that are not — the Permanent Outdoor Lights 2 is listed as not supporting cutting, while the Pro models are. If trimming to length is the reason you are buying, the word Pro in the product name is doing load-bearing work.

The specification that separates this from an ordinary string is IP68 on the strand, with the Y connector also IP68 and the control box and power adapter at IP67. That is a fully sealed run with a slightly less sealed brain, which is the right way round: the strand sits on the fascia in the weather for years, and the control box can be sited somewhere sheltered.

What you should not expect is invisibility. A permanent track is a visible line under the eave in daylight on every system sold, and any listing photo implying otherwise was taken at night. Colour-matched to the fascia it reads as trim, which is the honest best case.

We have not installed this system. The lengths, LED count, spacing, ingress ratings and the cut-and-reconnect capability above are Govee's published figures, linked in the sources below.

The DIY end of permanent holiday lighting: RGBIC LEDs in a track you mount once, app-controlled, at a fraction of a professionally installed system. The install is genuinely a weekend, and the warranty is short.

Permanent holiday lighting is a track of addressable LEDs mounted under the eave and left there. It is on for Christmas, and then for Halloween, and then as warm-white accent lighting in March. The reason people buy it is not Christmas; it is never climbing a ladder in December again.

The market splits cleanly in two. Professionally installed systems — Trimlight, JellyFish, Gemstone, EverLights and others — are dealer-installed, run several thousand dollars on a typical home, and carry long warranties. Govee is the DIY end: you buy the kit, you mount it, and it costs a fraction of that.

What you are actually buying with the professional systems is the install and the warranty, not better LEDs. Trimlight publishes a lifetime product warranty; Govee's is one year. If a channel section fails in year three, the difference between those two positions is the whole product.

Do not buy this expecting it to be invisible. Every permanent system is a visible track under the eave in daylight. The good ones are color-matched to the fascia and read as trim. None of them disappear, and any marketing that implies otherwise is overselling.

We have not installed this system ourselves. The warranty terms and control features above are the manufacturers' published figures, and the comparison page linked from here lays out where each brand's numbers come from.