On Saturday I screwed the forward covers on with nylon screws, and the fuse didn’t blow. The lights ran all night.
I didn’t take the time to do further diagnostic procedures this weekend, but will report back when I do. Riley the toe rail is aluminum, but the SS screws I was using go into the stemhead casting, which I think is pot metal (and butts up against the forward ends of the toe rails). There is no wiring channel at the deck/hull joint - the wiring to the forward running lights runs down the centerline of the deck under the forepeak, back to a bulkhead and then down the starboard side of the hull near the deck joint. The wiring and distribution panel including toggle switches and fuse holders are surely original, 1972. Neil when I get to further diagnostic procedures I’ll definitely work with one fixture at a time, as you and Alan suggest. Joel yes, when SS screws touch the stemhead it causes a short. The bases of the light fixtures are indeed black plastic. I’ve had my head and shoulders in the anchor locker from the v-berth and don’t find any exposed wiring touching the stemhead. Dennis the plastic lenses are complete domes in these new fixtures, unlike the partial domes in the previous ones. That’s part of why this problem is so mystifying. In any case, Alan has suggested a good diagnostic procedure, which I’ll follow soon. I needed a fix for a night race on Saturday, which I think I won. I was willing to run without the covers, as the bulbs are colored and bright, and the conditions weren’t rainy or windy enough to get the bow wet, but the nylon screws did the trick. Thanks again everyone. Cheers, Randy Stafford SV Grenadine C&C 30 MK I #79 Ken Caryl, CO Sent from my iPhone > On Aug 11, 2022, at 19:24, ALAN BERGEN via CnC-List <[email protected]> > wrote: > > Try troubleshooting with only one fixture, while the others aren't screwed > down. Then screw the cover on without the bulb inserted. If that doesn't blow > the fuxe, try it with the bulb inserted. If that blows the fuse, reverse the > bulb in the socket. If the problem still persists, rewire the fixture > (connect the fixture wires to the opposite source wires.). Keep us informed > about what you find. > > Alan Bergen > 35 Mk III Thirsty > Rose City YC > Portland, OR > > > > On Thu, Aug 11, 2022 at 5:11 PM Randy Stafford via CnC-List > <[email protected]> wrote: >> Hello Listers, >> >> I’m in need of your sage advice or at least hypotheses on an electrical >> problem. >> >> Here’s the background. Late last season my starboard running light bulb >> burnt out. It was a simple incandescent bulb, and the fixtures were >> probably original. So I thought hey, why not replace all three running >> lights with LEDs. In the process of doing that, I accidentally dropped the >> port fixture’s dome cover to the bottom of my slip (no chance of recovery; >> zero visibility). So, shit. I buy three new fixtures which have the same >> hole pattern as the old ones but of course take different bulbs so I had to >> buy LED festoon-style bulbs too. What started out as a simple $1.50 bulb >> replacement turned into a $150 project. And of course the new fixtures’ >> bases are thicker than the old, so I had to get longer stainless screws and >> drill and tap deeper holes in the stemhead casting. >> >> Well, after getting everything back together I discovered the running lights >> circuit is blowing its fuse within seconds of switching it on. But only >> when the dome covers are screwed on to forward fixtures (the new stern >> fixture including dome cover screws into the teak taffrail and causes no >> problems). I’ve now isolated the misbehavior to screwing the forward dome >> covers on. If I leave the covers off, the LED bulbs burn all night. I can >> press down on the fixtures and twist the LED bulbs around no problem - none >> of that causes any contact that shorts the circuit. If I put the covers on >> but don’t screw them down, the LED bulbs burn all night. But as soon as I >> screw those forward covers down, blown fuse. >> >> I’ve pulled the fixtures and looked carefully again at all the wiring, >> including in the forepeak under the deck. There is no pinched wire or cut >> insulation. The wiring to the fixtures goes through different (and much >> bigger) holes than any of the screws do. My heat-shrink butt connections >> are tight. As a short-term solution I just bought some nylon screws to hold >> the covers down. I haven’t tested that yet, but hopefully it works. >> >> Meanwhile I’m pretty mystified. Any theories? >> >> Thanks, >> Randy Stafford >> SV Grenadine >> C&C 30 MK I #79 >> Ken Caryl, CO
