Christmas Light Stringers: How To Choose Socket Wire, Spacing, And Spools

A Christmas light stringer is a run of wire with empty sockets spaced along it. You choose the bulbs, screw them in, and clip the line where you want it. It is how professional installers light rooflines, railings, pathways, and commercial buildings, because it lets you pick the exact bulb color and lens, replace a single bulb instead of a whole string, and build runs that fit the building instead of the other way around.

This guide covers how to choose a stringer: socket size, spacing, length, wire color, and wire type, plus when a 500 foot socket spool makes more sense, which bulbs and clips to pair with it, and a quick shopping list for the most common projects.

Stringers Versus Pre-Lamped Sets

A pre-lamped C9 or C7 set arrives with the bulbs already installed. It is quick, but you live with the colors and spacing it shipped with. A stringer arrives empty. That extra step buys you three things:

• Any bulb, any color. Our stringers take LED or incandescent bulbs with the matching base, so you can run warm white this year and red and white next year on the same wire.
• Easy repairs. If a bulb gets damaged, unscrew it and screw in a new one.
• Clip compatibility. Pro clips such as the TuffClips Tuff Tab are made for standard stringers with screw-in sockets. They do not fit pre-lamped strings.

Browse every length and spacing in our Christmas light stringers collection.

Step 1: Choose C9 Or C7 Sockets

The socket size decides which bulbs fit.

• C9 stringers use E17 intermediate sockets. C9 bulbs are the larger, bolder bulb and the usual choice for rooflines, two-story homes, and anything viewed from the street. Shop C9 stringers.
• C7 stringers use E12 sockets. C7 bulbs are smaller and suit low rooflines, porch railings, windows, walkways, and displays seen up close. Shop C7 stringers.

Not sure which size suits your house? Our C7 vs C9 guide compares them side by side.

Step 2: Choose Your Socket Spacing

Spacing is the distance between sockets, and it sets how dense the line of light looks.

For most homes, 12 inch spacing is the right call. It is easy to count (one bulb per foot), it looks crisp from the street, and it keeps the bulb count, and the cost, reasonable.

Step 3: Choose The Length

Our pre-cut stringers come in 25, 50, and 100 foot lengths, ready to use out of the box.

• 25 and 50 foot stringers have a male plug on one end and a female plug on the other, so you can connect several end to end and build a long run from one outlet. The C9 25 foot, 12 inch spacing stringer and the C7 25 foot, 12 inch spacing stringer are the most flexible building blocks we carry: easy to handle on a ladder and easy to fit around corners and peaks.
• 100 foot stringers such as the C9 100 foot stringer have a male plug only. Use one where a single long, uninterrupted run starts at the outlet and ends at the far corner.

To figure out how much to buy, measure each edge you plan to light in feet and add the totals together. On 12 inch spacing, that number is also your bulb count. Our Christmas light calculator guide walks through it for a whole house.

Step 4: Choose The Wire Color

The wire should disappear into whatever it is mounted on.

• Green wire blends into dark shingles, trees, shrubs, and lawns.
• White wire disappears against white gutters, fascia, trim, vinyl fences, and white columns.

Most of our stringers come in both. If your gutters are white but the run continues onto a dark roof, match the color to the surface that takes up most of the run.

Step 5: Know Your Wire Type, SPT1 Or SPT2

Most of our stringers use 18 gauge SPT1 wire. The C9 25 foot stringer with 6 inch spacing uses SPT2, which has thicker insulation. This matters the moment you start building your own cords, because slide-on vampire plugs are made for one wire type or the other and will not seat properly on the wrong one. Our SPT1 vs SPT2 guide explains the difference.

When To Use A Socket Spool Instead

A socket spool, sometimes called light line, is a 500 foot reel of socket wire with no plugs. You cut it to the exact length of each run and add plugs where you need them. It is the professional choice for large homes, commercial buildings, and anyone lighting the same property every year with runs cut to fit.

Here is how a custom run comes together:

1. Cut the socket wire to length between sockets.
2. Press an SPT1 male vampire plug onto the power end. No stripping or soldering is required.
3. Add an SPT1 female vampire plug on the far end if another run will connect to it.
4. Use SPT1 zipcord wire to build custom-length leads from the outlet to where the lights begin, and an SPT1 female inline pass-through plug to branch power mid-run without cutting the main wire.

Shop spools alongside the pre-cut lengths in our stringers collection, and see all plug styles in our vampire plugs collection. Our step-by-step guide to building custom cords covers the full process.

Pick The Bulbs

Any bulb with the matching base works, LED or incandescent. For a bright, efficient roofline we recommend our ProCore® LED bulbs:

• C9 Warm White ProCore® LED Bulbs, Faceted: E17 intermediate base, 3000K warm white, faceted polycarbonate lens that scatters light in multiple directions, 0.84 watts per bulb, dimmable, and rated for indoor and outdoor use. Sold in packs of 25.
• C7 Warm White ProCore® LED Bulbs, Faceted: E12 base, 3000K warm white, dimmable, packs of 25.

LED bulbs keep power use low. A 100 foot run of C9 ProCore® bulbs on 12 inch spacing is 100 bulbs, which works out to about 84 watts. For other colors and lens styles, browse C9 LED bulbs and C7 LED bulbs.

Pick The Clips And Stakes

Plan one clip per socket so the bulbs stand in a straight, even line.

• TuffClips Wedge Clip for C9: works on gutters and shingles and flexes over the socket to lock it in place. Also available in black for dark gutters and trim. Packs of 100.
• TuffClips Tuff Tab: a shingle tab clip for C7 or C9 stringers that sets the bulb facing outward from the shingle edge, the standard orientation for roofline installs. Packs of 50.
• 5 Inch Lawn Speed Stakes: push into the ground and hold a C7 or C9 socket upright for pathways, driveway edges, and flower beds. Packs of 25.

Our Christmas light clips buying guide matches every clip to every surface, and the pathway lights guide covers stake spacing.

Quick Shopping List By Project

If you would rather have everything in one box, our roofline bundles pair warm white faceted C9 bulbs with socket wire, clips, wire, plugs, and a photocell timer. For the full roofline picture, read our roofline Christmas lights buying guide.

Power Tips Before You Plug In

• Start each run at the end closest to the outlet so the male plug reaches power without an extra cord across the yard.
• Add up the watts on each circuit. A standard 15 amp household circuit handles about 1,440 watts of continuous load, and LED stringers use a small fraction of that. Our guide to how many LED lights you can plug in shows the math.
• Keep plug connections off the ground and add a drip loop so water runs away from the connection.
• Put the whole display on a photocell timer, such as our 2 outlet outdoor photocell timer, so it turns on at dusk without you thinking about it.

Questions about a specific roofline or a larger project? Email help@thechristmaslightemporium.com and we will help you put together the right stringers, bulbs, and clips.