Electrical circuit question

I have a workaround to my problem, but I’d still like to understand what’s going on.

I have two exterior outlets that I had installed for outdoor holiday lighting. There are on the same circuit and one is a GFCI.

The lighting set-up:

Two sets of lights, each connected to an extension cord, each of these plugged into a timer.

When this set-up is plugged into the GFCI outlet, everything works fine until (I’ve noticed) it rains. Then the GFCI trips and cannot be immediately reset.

I removed the entire series from the GFCI outlet and plugged it into the other outdoor outlet and it seems to be working fine.

Everything, including the outlets themselves, is less than a year old. The extension cords are heavy duty, outdoor rated (and brand new).

Any thoughts?


A little water leaking into any one of the connections can set off the GFCI. A regular breaker won’t be so sensitive. Do you have drip loops on your cords?

if they’re on the same circuit, which outlet is “downstream” from the other one?

Best practice is to have the GFCI unit “upstream” of any other outdoor receptacles so they are protected. That’s apparently not the case here though. Unless when moving from the GFCI receptacle you’ve also eliminated to current leakage point.

I was assuming a different circuit, but you’re right, it could just be that repositioning the cords eliminated the short.

I have no idea which outlet is upstream, but I take it they are incorrect and should be switched?

Also I’d never heard of a drip loop, but a quick Google search smartened me up. These cords - including the connections - are just lying on the ground. Should I elevate the actual connections somehow? Or just cover them with plastic or something?

Thanks for the responses.

In general you should keep them off the ground, and add drip loops to keep water out of the connections. Covering them with plastic may worsen the problem by collecting condensation but you can use some silicone tape. Do the outdoor outlets have weather covers?

The GFCI outlet will detect current loss for any outlet down the line. You can use the GFCI test button to check this, if you push the button and trip the GFCI outlet the other outlet would go dead also.

You might want to verify that the second (non-GFCI) outlet is being protected from the first (GFCI). Hit the test button on the GFCI, which should cut power to the GFCI outlet. Is the power to the second outlet also cut?

I assume these outlets both have outdoor covers, the kind with the little spring-loaded door which you open to plug something it. When you leave something plugged in the plug props the door open. What might be happening is that the rain is getting into the GFCI outlet when the door is propped open, but if you use the other outlet rain does not get in (or less rain gets in) because of being in a different location (different exposure to the elements).

You should be using an “in-use” cover on an outdoor outlet if you leave something plugged in for extended periods. This type of cover will keep the outlet dry even with plugs present.

This is an example of an In Use Outlet Cover

Some clarification is in order.

First, the second, non GFCI outlet also trips the breaker on the GFCI outlet (I thought it did not but it does).

Also, both outlets are designed for outdoor placement and covered with a plastic shield. They are also underneath an overhand so are not getting rained on.

The problem, I’ve decided, is moisture in the extension cord connections. These are out in the elements, and yes, it is raining when they trip.

So I guess I need some sort of enclosure at the connection points. I see some on Amazon, but they’re expensive and may not accommodate my connections (I have a couple, funky looking 3-way extension cords).

I’ll probably end up making my own enclosures out of a couple plastic storage bins.

If anyone cares I did just this yesterday. It hasn’t rained yet, but I feel pretty confident.

I placed a brick in the bottom to elevate the connections in case some water does find its way in. The brick also offers stability.

1st thing 1st.
Trip the outlet with the GFIC. Check the 2nd out let for power. If it still has power then outlets are wired wrong and second outlet does not have any protection. for someone’s life sake you should get this corrected.

I put up a lot of outside lighting for Christmas. Where a cord pluges into an extension and the timers I put them in a zip lock baggie making sure the opening is such that water will not go into the bag. I only get a tripped GFIC when there is really a storm blowing water around other wise this has eliminated the trips.

Yes, I have already done that.

But thanks.

Side note; Does the GFCI also provide “Arc Fault” protection? It would be labelled as such if it does. GFCI’s with AF protection are very prone to tripping. Less so with a lamp load, but they are still kinda fussy.

GFCI’s tend to trip more as they age. And if they are cheap ones.

Got interrupted above. Why would GFCI+AF be more sensitive? Are you talking about a GFCI+AF outlet, or a breaker?

GFCI outlets, especially when outdoors can get more sensitive over time. They have a spring mechanism that is designed in favor of unnecessary tripping instead of getting jammed with the circuit closed. There are solid state units now that avoid that problem.

Since GFCI+AF breakers cost a fortune an outlet must cost at least a fortune and a half.