Question about Intermatic Malibu 300W Power Pack Transformer ML300RTW

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I have Malibu 300W transformer. Photo cell turns lights on by 6 pm with little shade

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Photo cell has gone bad, or timer is wired incorrectly.
Open following link for correct wiring, and links to trippers and photo eye, plus troubleshoot steps:

If you need further help, I’m available over the phone at

Posted on Jun 25, 2012


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Posted on Jan 02, 2017



SOURCE: my malibu landscape 300w transformer does not want

Check that power pack is getting electricity.
Power pack should make a small humming sound when on.
Scratch a wire across both terminal screws and see if there is spark.
If a bulb burns out, and is not replaced, additional voltage 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.

Posted on Nov 23, 2010


SOURCE: I bought a Malibu 300W

I don't know if it burned out, but something is not right.
Malibu products come with 1-5 year warranty.
New product that stopped working should be exchanged for full replacement at place of purchase, except possibly the auction sites.
New Malibu product should work for many years.
Be sure to match bulb voltage with transformer voltage to avoid possible problems.
Mismatched bulb and transformer wattage should not affect a timer in short period such as 1 week.
Another thing to check is outlet polarity. Use circuit analyzer from home center to check outlet.

Posted on Jul 21, 2011

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1 Answer

Where can I buy a replacement photocell for my Malibu 300W low voltage landscape lighting transformer?

You can buy the Malibu Photocell Low Voltage sensor on eBay. Go to eBay and search "Malibu Photocell Sensor" and you should see it. Or search eBay item number 371829265599

Mar 26, 2016 | Intermatic Malibu 300W Power Pack...

1 Answer

We have an older Malibu 300w low voltage transformer that has a non-working timer and want to install a photo eye on it. The instructions for the photo eye as well as recent IFU from Malibu show 3...

How about this solution:
Don't use the photo eye from Intermatic, since unsure if older timers might not be made for that feature.
Instead, plug power pack into photo-eye timer.
Or plug power pack into ordinary wall timer:
Copy following links for resources:
Call Intermatic and they might have solution for photo eye.

If you need further help, I’m available over the phone at

Oct 06, 2013 | Intermatic Malibu 300W Power Pack...

1 Answer

Photo cell has short in wire,how do you repair

Splice the wire? Replace photocell?

What photo eye do you have? Intermatic ML series, or orher?
Where is the short?
What makes you think there is a short?
Have you tested the gfci?

If you need further help, I’m available over the phone at

Apr 06, 2013 | Intermatic Malibu 300W Power Pack...

1 Answer

Malibu Lighting ML300RTW Transformer Motor

Motor has gotten weak, and is overheating and soon will not work.
Some people report taking apart motor and cleaning gears.
Others report that they didn't record how the gears came off, and can not reassemble.
PB912M10 Clock module is not sold separately.

Switch power pack to override so lights are ON, and plug transformer into cheap wall timer.

Copy following link for tips to get power pack to last longer, troubleshoot, and warranty, etc.

If you need further help, I’m available over the phone at

Nov 04, 2012 | Intermatic Malibu 300W Power Pack...

1 Answer

What is the C for on the hookup?

The C terminal is for connecting a photo eye to power pack.

GotoGeek wrote answer for making the photo eye connection:

Malibu manual is missing details how to make this connection.

Dec 25, 2010 | Intermatic Malibu 300W Power Pack...

1 Answer

I have a Malibu ML88T timer on the garden lights. I guess the power pack is running can turn lights on off manually but the timer doesn't turn them off or on. Can this be repaired?

Is the timer wheel rotating - keeping time?
If so, are there pins for the wheel?
The other option is to purchase a photo sensor and let your lights stay on from dusk til dawn. The benefit of this arrangement is that as dusk changes across the seasons and daylight savings time, you don't have to keep adjusting on/off times.

Dec 01, 2010 | Intermatic Malibu 300W Power Pack...

1 Answer

Lights come on for about 2 min.and shut off. I turn off transformer for about 15 mins and turn on lights work for about 2 mins.

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:

Jul 03, 2010 | Intermatic Malibu 300W Power Pack...

1 Answer

On the malibu timer for outdoor lighting does not work

be sure that you have the AM/PM set properly. They are quite simple to use but this one can get you.

Feb 08, 2010 | Intermatic Malibu 300W Power Pack...

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