I recently moved into a house that has multiple outdoor outlets eventually feeding an outdoor lighting transformer and a small waterfall pump. There is an outlet on the interior of the house first before the wiring goes outside, originally with two GFCI outlets at the end wired in parallel, like so:
Breaker -> Outlet (indoor) -> Outlet (outdoor) -> Outlet (outdoor) -> GFCI (lighting) LINE -> GFCI (pump)
My plan was to replace the first (interior) outlet with a GFCI, and then all others connected to the Load side, with modern WR rated receptacles.
Breaker -> GFCI (indoor) LOAD -> WR Outlet (outdoor) -> WR Outlet (outdoor) -> WR Outlet (lighting) -> WR Outlet (pump)
The outdoor wiring is direct burial (not in conduit), and based on the condition of the outdoor receptacles I'd say is about the age of the house (c. 1975). The markings are "E30445 (UL) AWG 14 CU 2 CDR WITH AWG 14 GROUND TYPE UF-B 600 VOLTS SUNLIGHT RESISTANT". Most, if not all, of the outdoor outlets were plain old 1970's indoor-spec (non-WR), which were rusted, corroded and in some cases cracked (and yes, they were all still hot!). Note: the first two outlets are typically unused, and used only for the occasional leaf blower or some temporary outdoor device.
I have two separate but related questions/issues:
Is it fine, better or worse to have all of these outlets protected by a single upstream GFCI? The installation instructions for both lighting transformer and pump explicitly say they should be plugged in to a GFCI receptacle directly, which I assume is why it was done the way it was. What I've read (link, link) the issue with GFCI's in series is the nuisance of having to determine which load caused the fault. I'm not clear if having a second GFCI (in parallel) with the lighting/pump plugged directly in, if there is a GFCI upstream, is required or adds any additional safety.
When I replaced the first/indoor outlet with the GFCI (a Leviton GFTR1) as shown, it immediately faulted. I disconnected each outlet up the chain and once I disconnected the last outlet (pump), it stopped faulting and was fine for the past 4 months. Last week I had turned off the breaker, and when I turned it back on the GFCI faulted and wouldn't turn back on for two days (though everything was fine until I turned power off and then back on a few minutes later). I had just had some landscaping done, and so the ground had been super-watered, not sure if that would have had anything to do with it. Once it came back, it has not faulted again. My question then is... is this a problem or concern, or is this more characteristic of the high sensitivity of a modern GFCI with older outdoor buried wiring? As in, so long as the GFCI remains on is it safe to keep in operation?