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What Size Extension Cord for Halloween Net Lights?

For net lights, use a three-prong outdoor-rated cord, and almost any common gauge is enough. A net set is a light load, about 0.05 amps for an LED net and half an amp for an incandescent one, so a 16-gauge outdoor cord up to about 50 feet, or a 14-gauge for a longer run, carries one or a few nets without trouble. The gauge only becomes something to think about when you feed a whole row of incandescent nets down one long cord, or chain several cords together, or put the nets on the same cord as an inflatable or a fog machine. The worked example below shows exactly where that line falls.

Reaching a far hedge, or feeding several nets off one cord? Put the total amps and the cord length into the Extension Cord Voltage Drop Calculator and it tells you whether that cord holds voltage or whether to step up one gauge.

A net is a light load

Before you size a cord, you need the load it carries. A common 150-light net set draws about this much:

150-light net set Watts Amps at 120V
LEDabout 6 W0.05 A
Incandescent (mini)about 60 W0.5 A

Those are current product-label values; the full breakdown, including how to get the amps from a bulb count, is in how many amps Halloween net lights use. For cord sizing, what matters is that even an incandescent net at half an amp is a fraction of what any outdoor cord can carry.

The cord's amp rating is not the limit here

A 16-gauge outdoor cord is good for roughly 10 amps, a 14-gauge for about 13 to 15, and a 12-gauge for 15. A single net at half an amp, or even a handful of them, is nowhere near any of those ceilings, so overheating the cord is not the concern. The number worth watching instead is voltage drop, the small amount of voltage a long cord loses along the way. Keeping that drop under about 3 percent keeps the far end of the display as bright as the near end, and the longer the run the more it adds up.

Worked example: a few LED nets on a long cord

Say you cover a row of bushes with six LED nets, 0.05 amps each, so 0.3 amps total, and feed them through 100 feet of 16-gauge cord, the thinnest most people own. Voltage drop on a cord is two times a copper constant (12.9) times the amps times the one-way length, divided by the wire's cross-section in circular mils (2,580 for 16-gauge):

6 LED nets × 0.05 A = 0.3 A total

Drop = 2 × 12.9 × 0.3 A × 100 ft ÷ 2,580

Drop = 0.3 volts, about 0.25% of 120 V

Three-tenths of a volt over 100 feet is nothing you will ever see. For LED nets, the honest answer is that the cord is almost never the constraint, so use the shortest outdoor-rated cord that reaches and do not overthink the gauge.

Where the gauge starts to matter

The math changes when you put a long row of the old incandescent nets on one feed. Picture eight incandescent sets along the front of the house, split into short daisy-chains that all plug into one multi-outlet cord fed from a single run. That is 4 amps on the feed:

8 incandescent nets × 0.5 A = 4.0 A total

100 ft of 16-gauge: 2 × 12.9 × 4 × 100 ÷ 2,580 = 4.0 V, about 3.3%

100 ft of 14-gauge: same load, 2.5 V, about 2.1%

At 4 amps over 100 feet, the 16-gauge cord slips just past the 3 percent guideline and the far nets start to look a touch dimmer. Switching that run to a 14-gauge cord (4,110 circular mils) brings the drop back under the line, and a 12-gauge cord has room to spare. The load, not the single net, is what called for the heavier cord. The same thing happens if you chain two or three long thin cords together, because the lengths add up, and faster still if the nets share the cord with a blower fan or a fogger.

A cord guide you can use

  • One or a few LED nets, any reasonable length: a 16-gauge outdoor cord is fine. Shorter is always better.
  • A long row of incandescent nets, 50 to 100 feet: add up the amps first, then step up to 14-gauge, or 12-gauge for the heaviest runs, to hold voltage at the far end.
  • The cord also feeds an inflatable or a fog machine: total every amp on the cord and size to that. A 12-gauge cord is the safe default for a shared run.
  • Always outdoor-rated and three-prong. The letter W on the jacket means it is built for wet locations; the third prong is the ground. Plug it into a GFCI outlet.
  • Use one cord, not a chain of them. Each added cord adds length, adds voltage drop, and adds a plug-to-plug connection that can work loose or let water in.
  • When a big display outgrows your outlets, call a licensed electrician. A dedicated outdoor circuit is the right answer for a large yard, and it is not a do-it-yourself job.

NEC reference

National Electrical Code (NEC) 2020. Flexible cords are covered by Article 400 and are meant for temporary use, not permanent wiring. The 3 percent voltage-drop figure is the Informational Note to 210.19(A), which is guidance rather than an enforceable limit. Outdoor receptacles require GFCI protection under 210.8(A). The circular-mil values used above are the physical wire sizes from Chapter 9, Table 8, and the wattage figures are typical 2026 product-label values, not code values; your own labels govern.

Results are for reference only. Verify against the applicable adopted edition of the NEC and consult a licensed electrician for code compliance.

For the whole season

The Holiday Electrical Safety Handbook

This guide answers one question. The Handbook covers Halloween through New Year's: how many amps a circuit can really carry (a 15 amp breaker means 12 amps, a 20 means 16), extension cords, GFCI outlets, outdoor displays in the weather, the Thanksgiving kitchen, tree lights, space heaters, and what to do when something goes wrong. Every figure is pre-converted to amps, so you add instead of calculate.

Read on Kindle Paperback on Amazon Free circuit map and load worksheet

Get the next seasonal safety check by email

Optional. Short emails before each holiday, written for homeowners.

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