Bad Winter Yields Outdoor Light Trouble
#11
For ten years my Malibu transformer worked flawlessly with my underground low voltage lights and deck lights. The lights are safely within the transformer's 200-watt power limit.

This El Nino winter apparently did a number on one of the underground wires. Last night a short developed and heat built up in the transformer, frying it. Eventually the 120 v cord's insulation melted and the 15-amp circuit breaker threw. Surprisingly, the GFCI outlet indoors never tripped (Murphy's Law).

I'm not sure if these transformers are safety fuse protected, but perhaps they should be. The Malibu now looks like nothing but a black blob. What I intend to do next is install an outdoor outlet that has its own GFCI and replace the one indoors. Then when spring eventually arrives, I'll buy a new transformer, replace the underground wire, and reconnect the lights. Any other suggestions?
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#12
Edwin Hackleman said:

Any other suggestions?



Yeah, get rid of it before it burns down your house.
I never understood the fascination with outdoor or pathway lights. If you don't know your own property after 2 months, you never will.

I understand people are drawn in by shiny pretty things, but so are raccoons.
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#13
Thank you, but I will wait for another suggestion. Millions of houses are lighted in the USA with low-voltage bulbs. These lights also provide safety, but that's not the issue here. I am looking for repair advice from another engineer or technician -- not an off-topic blast.
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#14
The problem was loose wiring connections creating a arc. Looks like you could of used a Dual Function Circuit Interrupter (DFCI) breaker rather than the GFCI. The DFCI is suppose to prevent electrical arc faults which lead to fires plus provide ground fault protection.
Any free advice given is worth double price paid.
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#15
A GFCI isn't meant to protect against overcurrent faults. The current on the line side of the transformer stayed balanced so it did what it is supposed to do. Someone must be building a transformer with built in overcurrent protection on the load side. The other option is an inline fuse holder on the low voltage side.
Blackhat

Bad experiences come from poor decisions. So do good stories. 


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#16
"The other option is an in-line fuse holder on the low voltage side. "

Agreed. That's what this transformer should have had on board. Looks like a cost-savings tactic by the MFG.

What you are also saying is that even if this transformer was plugged into a GFCI outlet, it would still have fried and likely set fire to the house if the 15-amp breaker had not tripped and shut it down. Correct?
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#17
Correct. At some point the current in the primary side would likely have exceeded the rating of the breaker but if that would be in time to prevent a fire is questionable.
Blackhat

Bad experiences come from poor decisions. So do good stories. 


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#18
I figured as much. The outside wall where the timed transformer was hanging scorched. I'll have to scrape and repaint that. LOML says that we lucked out. I have to agree with her. Close call.

For my own curiosity, I'd like to find exactly where the low-voltage line shorted, not that it means anything. Could be several locations along the cable.
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#19
Ummm....Herbie????


"I never understood the fascination with outdoor or pathway lights. If you don't know your own property after 2 months, you never will."


He may know his house but I certainly don't when he invites me and the Missus over for dinner.
Dumber than I appear
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#20
Dumb_Polack said:


Ummm....Herbie????


"I never understood the fascination with outdoor or pathway lights. If you don't know your own property after 2 months, you never will."


He may know his house but I certainly don't when he invites me and the Missus over for dinner.



What about when it snows? Path lights are very helpful during a snowfall or very dark nights.
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