300W transformer shuts off after 1-3 hrs (231w: OK w 181 watts)

1) Copy following link for malibu power pack tips for longer transformer life:
http://waterheatertimer.org/Malibu-power-pack-stopped-working.html

2) Two plug choices on each outlet, Plug power pack into other outlet on receptacle.
Inspect for damage on outdoor outlet.
Replace outdoor outlet, and do not use quick connects. Connect wire directly to screws on side of device.
Replace GFCI outlet.

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Try it... should work
http://waterheatertimer.org/Malibu-power-pack-stopped-working.html#install
However minimum load for ML121 is 80% load rating.. so 80 watts is ok for 100 watt transformer... 60 watts is low and can cause early failure of transformer.
Gene

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How many watts of lights are connected to the transformer. It should be between 250 and 300 watts.
Gary

Instead of 2 seperate wires run 1 long continuous wire & splice each light into it as you go along.There will be less resistance & the last light will be almost as bright as the first with very little difference in between.

Usually 50 - 75 ft. is as far as you want to go, especially with 16 gauge wire. What happens is the lights get dimmer as the length of the run increases. If you don't mind the lights getting noticeably dimmer, go ahead and add the other 4 lights. Using a heavier (12 gauge) wire will help a lot. You'll want the 12 ga. to start at the transformer, preferably running the whole length. Also, using a smaller watt bulb will help.

If you have a 120 volt outlet near the approximate middle of the new (total 150 ft.) run, you could relocate the transformer to that location and have two 75 ft. runs in 2 directions.

You checked that power pack is getting electricity.
Scratch a wire across both terminal screws and see if there is spark.
If a bulb burns out, and is not replaced, additional power can burn out other bulbs.
Power pack should be unplugged if bulbs are not burning since that can burn out power pack.
Change out a couple bulbs and then plug-in power pack.
Check connections where lights tie into wire.

My power pack was doing same thing, I bought another power pack from Home Depot to check my lights. All but 2 bulbs were burned out. I replaced bulbs and returned new power pack.. and then power pack quit for good a month later.

I found tips to preserve power packs:
1) Match wattage of bulbs with wattage of power pack
-15 each X 20 watt bulbs = 300 watts, so install 300Watt power pack
2) Installing a 500W power pack on 300W of bulbs will burn out bulbs and power pack.
3) Replace bulbs as soon as they burn out or other bulbs will burn out and power pack will burn out.
4) When working on bulbs, unplug power pack or it may burn out.
http://www.malibulights.com/guides_support/low_voltage_planning_guide/select_your_power_pack

Unfortunately when the power pack stops working there is no solution.
Your power pack has electricity so that is not the problem.
The bulbs turn on, so the bulbs are ok.
That means the power pack has malfunctioned, and needs to be replaced.

I did find some tips to help folks preserve their power packs:
1) Match wattage of bulbs with wattage of power pack
-15 each X 20 watt bulbs = 300 watts, so install 300Watt power pack
2) Installing a 500W power pack on 300W of bulbs will burn out bulbs and power pack.
3) Replace bulbs as soon as they burn out or other bulbs will burn out and power pack will burn out.
4) When working on bulbs, unplug power pack or it may burn out.
http://www.malibulights.com/guides_support/low_voltage_planning_guide/select_your_power_pack

There is a break in the main wire between the 2nd and 3rd lights. Has anyone been digging or working in the yard lately?
While the transformer is fully loaded, six 20 watt bulbs won't overload it.

Unless you have the optional photo cell, I'd imagine you are overloading the transformer. Total up your lamp wattage and be sure it is less than the 300W rating of the transformer. The lights usually range from 10 to 50 watts, so you could have 30-10watt lamps or 6-50 watt lamps. The other possibility is that you have a short in your wiring or fixture. In either case if you overload the transformer it should cycle off to protect from overheating, and when it cools, it will restart. Try connecting just one luminaire to the transformer and see if it works. See link:http://www.malibulights.com

There are two sets of terminals on the 600 watt x-former. If you have two 300 watt circuits, use one 300 W circuit on one output, and the other 300 W circuit on the other output. Use terminals A & B on each side. Each circuit will have 12 volts.

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