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Elegant Outdoor Lighting
10-06-2009, 06:06 PM
Called in for service call on someone else's system. Multi-Tap 12-15v, 3 breakers- (Vista?)

Complaint- 1 breaker in transformer flipped after homeowner replaced bulb in particular fixture. (Fixture 3)

1 circuit breaker (15 volt tap) flips when transformer has been off for a while and then turns on. Breaker can be manually turned back on and then will stay on. Will stay on even if creating a surge by powering transformer on and off rapidly.


Checked “Fixture 3”:
BAB 20 watt lamp
11.5 Volts at Fixture w/out lamp
1.7 amps

So it looks like we have the right lamp and no short.

At transformer:
125 volt on primary side.

15 volt tap (only thing connected to breaker that is going off):
“Wire 1- incl. Fixture 3” = 11.5 amps
4 fixtures
80 watts total

oops… according to Ohm’s Law it should be in the neighborhood of: 5.33-6.67.

My theory is that it seems like we probably have corrosion at a connection. Amperage doesn’t seem to be high enough to have a short. What do you guys think??

“Wire 2”
5.8 amps- normal

Elegant Outdoor Lighting
10-06-2009, 06:18 PM
Although, I did not check the other 3 fixtures on run. If they had 50 watt lamps plus the 20 watt that I did check, the math works out for amperage and the main wire (12-2) should be within capacity.

I should have taken a picture of the transformer. Anyone know who's transformer comes with the 3 white toggle switches for breakers? Transformer not labeled anywhere I could see. Perhaps the breaker is going bad? Anyone have experience with this? I am used to using fuses.

Thanks guys

Lite4
10-06-2009, 07:20 PM
Sounds like a Justin or MDL transformer. Could be corrosion or a loose connection.

S&MLL
10-06-2009, 07:28 PM
Cut the fixture out and see what happens.

Alan B
10-07-2009, 09:26 AM
Or swap the home runs to a different common tap. I.e take the home runs that are connected to the bad curcuit/bad common port and connect them to a working one--take the working one home runs and connect to the "bad" common. If the bad curcuit still trips you know its the transformer. If a new curcuit trips you know its a problem iwht the home run (short somewhere).

Alan

JoeyD
10-07-2009, 10:13 AM
Like Alan said but your amp probe shoudl tell you if there is any problems. If you are that far under the 25a rating than more than likely you have a faulty breaker on the common. Try moving to another common tap. Should be fairly easy to solve. Amp probe is the best toom you can have in these situations!

Pro-Scapes
10-07-2009, 10:06 PM
Dont forget a good visual inspection. Is that socket showing signs of wear ?

YHou could have a bad breaker or a bad connection.

Something that grabbed me. When you said fixture 3 has 1.7 amps right after you said it 11.5v with no lamp I assume your saying 1.7a with the lamp in there ?

Also you did not check the other 3 fixtures. There could be a problem in one of the other 3 even tho the client did not replace them. On intermittant problems I also do something scientific I call the jiggle test. I will wiggle sockets.... connections I can get to...etc and see if that causes a trip. I have found many problems like this.

Depending on my findings I would either at this point replace the breaker or rebuild that run if the workmanship looked second rate.

Elegant Outdoor Lighting
10-12-2009, 01:21 PM
Thanks everyone for your suggestions...

Turns out it did have 2, 50 watt lamps on the run. So, the amperage does make sense...so most likely the breaker is going out. Changed the lamps to 20s and it seems to work fine, for now...