WANTED: GFIC Tutorial

[crazytrain83]

Hey guys....

Miserable Minnesota day yesterday. Started 34 degrees with freezing rain...finished 6 below with three inches of snow (Global Warming my big fat frozen butt!)

When the show startes at 5:30, we noticed that we were missing 8 channels. Turns out a GFIC had been tripped. We reset it, and show worked fine the rest of the night.

What I'm wondering is exactly how a GFIC works, what made it trip, and what I should be doing when it trips.

Any help would be greatly appreciated!

-Eric

[Dale W]

Not an expert or trying to give a tutorial, but GFCI trips when the circuit leaks voltage in the socket. This is usually caused by water in the circuit causing it to short out.

In Mississippi we do not have the snow, ice melt/refreeze that you do, but we do have to deal with heavy rains.

I have found that by lifting the connections off the ground, you eliminate many of the trips that are caused by wet cords/connections.

When I have one trip, and it is after a rain, I will usually reset the breaker and that is all that is needed. If it becomes a chronic problem, then I will lift the plug off the ground at the connection on both side of it by placing the plug on a bent hanger to lift it and hold it off the ground.

[iresq]

Here is how I understand it. Electricity flows from hot to neutral. GFI outlets/breakers monitors this flow. If it detects any current flowing from hot to ground, it trips.

How does this relate to Christmas Decorating? Let's say there is an exposed wire and it's touched. The electricity runs through you looking for ground. GFI see this and trips. That's the safety aspect of it.

The pain in the arse is when electricity leaks from lights to ground because of wet conditions. This leak may or may not be enough to hurt you but it will cause the breaker to trip. When it trips, you can try resetting. If it trips again, just leave it off until the rain stops.

[-klb-]

GFCI's measure the difference in current between the hot and neutral. They trip if that difference exceeds a safety threshold.

So basically, they trip if power leaks in or out of the circuit protected by the GFCI.. For example:

• 
  
• if contaminated (and thus conductive) water forms a thick enough film between the ground plug and the hot plug on an extension cord, you often get a trip.
  
• If the hot lead of an extension cord socket gets into a puddle of less than pure water, you will probably get a trip.
  
• If you have a path form from the hot of one circuit to the neutral of a different circuit, you should get a trip.
  
  
  
• If you are wearing insulated shoes, and you were to grab the hot and neutral of the same circuit, you are not causing any imbalance in the load, just additional balanced load. The GFCI will not trip...

Here are the things I do to try to prevent GFCI trips:

• 
  
• Ensure that outdoor GFCI's have covers that are rated for use in the rain. This requires a cover that will close over an extension cord plugged into the socket.
  
• Only run grounded cord as far as the controllers. After the controllers, all cord has no ground.
  
• Use plastic stakes, or other non conductive methods to keep plugs above the ground.
  
• Mount my wire frame mini trees on plastic tent stakes to keep them isolated from ground.

Last year, my biggest source of trips at the house was a film of water getting into the connection between the 12/3 cords and the controller cords.. They would even trip when the show was not running.. The second largest issue at the house, and the largest at the city show was connections, or even pass through plug ends sitting on the ground...

- Kevin

[crazytrain83]

Thanks guys.

That all makes sense to me.

I just wanted to make sure that if resetting the tripped GFIC brings the show back up, I'm not ignoring some bigger problem that could either damage my hardware or cause injury.

Since this was a one-time deal, I guess I'll blame the weather and call her good to go!

[Steven]

crazytrain83 wrote:

I just wanted to make sure that if resetting the tripped GFIC brings the show back up, I'm not ignoring some bigger problem that could either damage my hardware or cause injury.

GFCI use electronics to trigger, not springs like some circuit breakers. This means that repeatedly tripping and resetting a GFCI will not change its sensitivity, so you don't need to worry about that.

Of course, if the circuit is drawing current when the GFCI trips, then there will be some arcing at the contacts, so they could wear out this way, but this would most likely result in no power.

The reason GFCI's have test buttons is that if the electronics goes bad, power will still flow.

What probably happened is the first rain of your lighting season got a dirty connector wet, which then leaked current to ground. After it rained for a while, the rain washed the dirt away, leaving just pure rainwater, which doesn't conduct very well.