Will a Halloween Fog Machine Trip a Breaker?
It can, and it is one of the most common ways to pop a breaker on Halloween night. A typical home fog machine draws far more power than a string of lights. A 1,000-watt fogger pulls about 8.3 amps all by itself, which is most of what a 15-amp circuit should carry, and it surges even higher for a moment each time the heater kicks back on. Put a second fogger, or a pile of incandescent lights, on that same circuit and the breaker will trip. The fix is not a bigger breaker. It is knowing how many amps your fogger draws and spreading the load so the total stays under the limit.
Running the fogger on a long cord to a far corner of the yard? Check the run first on the Extension Cord Voltage Drop Calculator. A fog machine is mostly a heating element, and a long, thin cord starves it of voltage, so it heats slower and works its pump harder. Getting the cord right matters as much as getting the breaker right.
How many amps a fog machine draws
A standard wall outlet in the United States is 120 volts. To turn the wattage printed on your fog machine into amps, divide the watts by 120. That single number tells you how much of the circuit it uses. Here are the common sizes sold for home Halloween use, with the amps worked out:
| Fog machine rating | Amps at 120V | Share of a 15A circuit's 12A limit |
|---|---|---|
| 400 W (compact) | 3.3 A | about a quarter |
| 700 W | 5.8 A | nearly half |
| 1,000 W (common yard size) | 8.3 A | two thirds |
| 1,200 W | 10 A | two thirds and then some |
| 1,500 W | 12.5 A | over the working limit alone |
These are typical values from product labels sold in 2026; your own machine's plate is what counts, so read it. The pattern is what matters: a fog machine is a small electric heater, and heaters are heavy loads. Even the mid-size 1,000-watt unit most people buy uses two thirds of what a 15-amp circuit should carry before you plug in a single light.
The number you cannot go over
Most homes have 15-amp or 20-amp branch circuits behind their outlets. You do not get to use every last amp. Decorations that stay on all evening count as a continuous load, and the National Electrical Code (NEC) says a circuit should be loaded to no more than 80 percent of its rating for a continuous load. That gives you a practical ceiling:
15-amp circuit: 15 × 0.80 = 12 amps = 1,440 watts
20-amp circuit: 20 × 0.80 = 16 amps = 1,920 watts
A fog machine muddies this a little because its heater cycles on and off rather than running flat out the whole time, so on its own a single fogger is not strictly a continuous load. But it almost never runs on its own. It shares the circuit with lights and inflatables that are continuous, and every time the heater re-energizes it pulls a brief surge above its rated amps. Treat the fogger at its full nameplate amps and keep the whole circuit under the ceiling above, and the surge has room to happen without tripping anything.
Worked example: one fogger fits, two do not
Say you put a 1,000-watt fog machine, one inflatable, and some LED lights on a single 15-amp circuit:
1,000 W fog machine ÷ 120 V = 8.33 A
250 W inflatable blower ÷ 120 V = 2.08 A
100 W of LED string lights ÷ 120 V = 0.83 A
Total: 1,350 W = 11.25 A
At 11.25 amps you are just under the 12-amp working ceiling of a 15-amp circuit. It holds, though there is not much room left. Now add a second 1,000-watt fogger to the same circuit:
Two 1,000 W foggers = 2,000 W
Plus 250 W inflatable and 100 W of LEDs = 350 W
Total: 2,350 W ÷ 120 V = 19.6 A
At 19.6 amps this trips a 15-amp breaker right away, and it is over the 16-amp working limit of a 20-amp circuit too. This is exactly the setup people describe when they say two foggers plus a few floodlights keep popping the breaker. The answer is not a bigger cord and not a bigger breaker. It is putting the second fogger on a different circuit, one fed from a separate breaker, so neither circuit is overloaded.
Why it trips the moment the fog kicks in
A fog machine spends a while heating up, then holds temperature by cycling its heater on and off. Each time that heater switches back on it draws a short surge above its steady amps. If the circuit is already loaded close to the limit, that surge is the extra push that trips the breaker, which is why a display can run fine for twenty minutes and then go dark the instant a big cloud of fog goes out. It looks random. It is not. It is the heater cycling on top of a circuit that had no headroom left. Leaving real margin below the ceiling, not creeping right up to it, is what keeps the surge from mattering.
Do this instead of upsizing the breaker
- Read the fogger's nameplate and divide by 120. That is your amp draw. Subtract it from the circuit's 12- or 16-amp ceiling to see what is left for lights.
- Give a big fogger its own circuit. The cleanest fix for a 1,000-watt or larger machine is to run it from an outlet on a different breaker than the rest of the display.
- Never swap in a larger breaker to stop the trips. The breaker is sized to protect the wire in the wall. A bigger one lets that wire overheat, which is a fire risk, not a fix.
- Keep the heater's surge in mind. Do not load the circuit right to the ceiling. Leave headroom so the cycling heater has somewhere to surge.
- When you need more outdoor capacity, call a licensed electrician. Adding a dedicated outdoor circuit is the right answer for a big display, and it is not a do-it-yourself job.
NEC reference
NEC 2020. The 80 percent ceiling for a continuous load comes from NEC 210.20(A) and 210.19(A); a continuous load is one expected to run for three hours or more, per the Article 100 definition. Branch-circuit and outlet ratings follow Article 210. The wattage figures above are typical product ratings from 2026 retail listings, not code values; your own machine's nameplate is what governs.
Results are for reference only. Verify against the applicable adopted edition of the NEC and consult a licensed electrician for code compliance.
Get the full guide
NEC Code Quickstart
This guide covers one calculation. NEC Code Quickstart walks all twelve exam calculations start to finish, each with a worked example and the exact code reference: ampacity and derating, breaker sizing, voltage drop, box and conduit fill, grounding, dwelling load, range and dryer demand, motor circuits, and transformer current. Written for the 2023 NEC with notes for the 2026 edition.
Related
- Holiday Circuit Map and Load Worksheet (free PDF): a fill-in circuit map for your own house plus six one-page seasonal safety cards, with every load already converted to amps.
- How Many Halloween Decorations Can I Run on One Outlet?: add up the whole display, not just the fogger, against the circuit limit.
- Extension Cord Voltage Drop Calculator: check whether a cord holds voltage over its length and load.
- Do Outdoor Halloween Decorations Need a GFCI Outlet?: the shock-protection rule for anything plugged in outside.