What is a GFCI?
A Ground Fault Circuit Interrupter (GFCI) is a safety device that protects people from electrical shock. Unlike circuit breakers that protect equipment and buildings, GFCIs monitor electrical flow between the "hot" and "neutral" sides of an outlet to prevent dangerous situations.
When looking at an outlet, the larger vertical hole is the neutral side, and the smaller vertical hole is the hot side. The flow of power going from hot to neutral should always be the same, but due to environmental conditions like rain, power can be misdirected and funnel into what's called a "ground." A ground is quite literally an object - like a human - that provides an electrical current with connection to the earth.
A GFCI outlet has an internal current transformer that detects fluctuations of power greater than 4 to 5 milliamps. When it senses this, the GFCI will shut down the circuit in less than one-tenth of a second, significantly reducing the chance of injury. A GFCI will also trip if more than 15 or 20 amps is drawn, similar to what a circuit breaker does.
How GFCIs Work:
Monitor power flow between hot and neutral connections
Detect power fluctuations above 4-5 milliamps
Shut down circuit in less than 1/10th of a second
Also trip if current exceeds 15-20 amps
Step-by-Step Troubleshooting
Isolate the Problem
Unplug all lights from the GFCI
Reset the GFCI using the center button
Reconnect lights one section at a time
Note which section causes the GFCI to trip
Inspect for Damage
Check plugs for water accumulation
Look for stretched or damaged wires
Search for signs of rodent damage
Examine wire casings for staple punctures
Preventing GFCI Trips
Follow these proactive measures to keep your lights working:
Use coaxial plugs with rubber o-rings for waterproofing
Our commercial-grade mini lights feature coaxial connections that have a rubber o-ring (the clear plastic ring in the photo above) which protects the electrical connection from incoming moisture and dust build up.
Never tape connections - it traps moisture
Apply dielectric grease to plugs
Ensure plugs do not sit in water such as puddles or gutters.
It also helps to prop plugs off the ground in areas that are susceptible to pooling.
Prevent water from running down wires into connections
Simply bend the extension cord so that water drips off the wire before entering the plug. This applies to plug connections at the outlet, as well as where light strings and power cords are connected to one another throughout your installation.
Testing Your GFCI
Regular GFCI testing is essential, especially before installing holiday lights:
Press the TEST button to cut power
Confirm the RESET button pops out
Push RESET to restore power
Important: Don't assume a working outlet means GFCI protection is active. Older outlets may still provide power even if GFCI protection has failed.
Measuring Current Load
Use a clamp meter to measure the current draw for each feature. For safety, keep total current 25-30% below your circuit's maximum capacity (typically 15-20 amps for household circuits).