12V AC garden light transformer woes

[dave163]

I have a few 12V AC garden lights, wired in parallel to a 240V transformer which is plugged into a wireless-operated switch which is plugged into a standard plug socket in rhe garden shed. The shed is properly wired to the house (shielded cable, fitted by electrician etc) and a wireless switch by the back door of the house turns them on or off. The kit is all that standard black modular low voltage garden stuff, with waterproof two pin connectors and the transformer is IP rated for tolerating damp outdoor sheds. Power rating 30W, and running 4x4W LED bulbs.

So far so good. Except the transformers last a few months (and a few hours of lighting on, all said) before they conk out. Sometimes taking the RCD with them. Tonight it tripped the fuse, and when I tried it again it offered a few minutes of occasional feint flashing garden lights before giving up the ghost.

Nothing else electric in the shed is causing me any issues.

But it's a pain to now on probably my fourth dead garden light transformer in a couple of years. And they are £30+ each so starting to mount up. Different brand and supplier each time, always well above power margin. Are low voltage AC garden lights just best avoided, is it reasonable for transformers to blow this often and have to replaced? If not, what is the solution?

 

[SUNRAY]

I'd like to find some more (better quality) 12V garden lights, I find the plastic fails after 5-10 years.

Mine started out as a set of 2x 21W about 2ft high with 5A transformer then added 2 sets of 4x 8W about 1ft high with 3A transformer - 7 used) However I'm using a 110VA transformer from a microfiche reader. That has been in service for >25 years. In the early days those lights would have been on for probably 5 hours a night so all had lots of use.
As plastic broke up and landscaping changed we now have 17 1ft bollards with a mix of 3W LEDs and 8W halogen purchased as 2 sets of 10 but all 'spares' now used up due to UV damage.

At one stage I was using one of the transformers that came with the lights but soon extended the other system to feed those lights when a second transformer failed. My experience seems to match yours so my suggestion is to get a 12V transformer that is better quality than the garden products.

 

[dave163]

Thanks, I looked up the latest transformer's supplier as it may still be under warranty and was reading reviews last night. All very positive, yet several mentioning they had to regularly replace the transformers! What's up with these things, is low voltage garden lighting just impossible to design to last more than a few months?

I wouldn't mind quite as much but the shed from where the lights come is itself supplied by a spur off the kitchen ring main so when the transformer fails it shuts the kitchen down, off goes the freezer and it's hunt the dodgy appliance until I check and find the garden lights are off.

 

[ericmark]

Wire wound transformers last for decades, but switch mode power supplies have electrolytic capacitors in them which have a limited life.

 

[SUNRAY]

Do you feel confident and competant enough to fit a transformer such as this

in an enclosure and wire it up safely

https://cpc.farnell.com/multicomp/mcta030-12/30va-toroidal-2x12v/dp/FF01542?CMP=CPC-ebooks-BIGBOOK2019

 

[dave163]

No I don't, nor do I want to blow up the house!

Is it just a fact of life that garden 12VAC transformers conk out and need replacing every few months? Reading some of the reviews I'm leaning towards "yes" but that just doesn't feel right. Are there any decent ones out there?

 

[SUNRAY]

No I don't, nor do I want to blow up the house!

I appreciate the definitive honesty

Is it just a fact of life that garden 12VAC transformers conk out and need replacing every few months? Reading some of the reviews I'm leaning towards "yes" but that just doesn't feel right. Are there any decent ones out there?

Sorry I can't help with that, I don't use them.

 

[FrodoOne]

I have a few 12V AC garden lights, wired in parallel to a 240V transformer which is plugged into a wireless-operated switch which is plugged into a standard plug socket in rhe garden shed. The shed is properly wired to the house (shielded cable, fitted by electrician etc) and a wireless switch by the back door of the house turns them on or off. The kit is all that standard black modular low voltage garden stuff, with waterproof two pin connectors and the transformer is IP rated for tolerating damp outdoor sheds. Power rating 30W, and running 4x4W LED bulbs.

4 x 4W LEDs means 16 W supplied by a 30 W transformer - 1.3 Amps at 12 V.

A "Power" rating of 30 A is quite low for even a few LED Garden Lights.

But it's a pain to now on probably my fourth dead garden light transformer in a couple of years. And they are £30+ each so starting to mount up. Different brand and supplier each time, always well above power margin. Are low voltage AC garden lights just best avoided, is it reasonable for transformers to blow this often and have to replaced? If not, what is the solution?

At £30+ each. it may be that you are getting "ripped off".
(See https://www.bunnings.com.au/hpm-12v-60w-garden-light-transformer_p4374665
When you convert the Currency, this is half the price for twice the Wattage/Current.)

I suggest that you should invest in a higher Wattage Transformer - from a cheaper "source" - for the Supply.



IN ADDITION,
D0 you have an "in-line" fuse (rated at 2 A or 3 A) on the secondary (12 V) side of the transformer.

You wrote
"Tonight it tripped the fuse, and when I tried it again it offered a few minutes of occasional feint flashing garden lights before giving up the ghost."

Was the fuse mentioned in the 230 V supply to the Primary?
It sounds as though you may have an intermittent short-circuit in your "Garden Wiring".