the bullet-proof transformer

[sitelights]

We have installed a few tons of Acme Pool & Spa low voltage lighting tranformers; the workhorse of choice when you want a bare-bones unit with just the right specs: stainless steel R3 housing, fully potted in a sand/epoxy mix, auto-reset thermal circuit breaker on the primary side, Faraday shield, a sturdy grounding lug, 12, 13 and 14v secondary leads, 4 1/2" knockouts (2 per side) and quite good regulation (the ability of the transformer to deliver its secondary output under load compared to similar units). We've lost a few to lightning strikes but otherwise have never had a unit fail. On the minus side, the 500w T-79105SR/SL (the SR has primary leads on right; SL on left, to me pointless feature that merely doubles their inventory problems...more below*) is shipped with numerous sharp (razor sharp) edges around the wiring compartment. I have never encountered a T-79105 that did not leave me bloodied but unbowed. The wiring compartment is accessed by removing a unplated phillips-head self-tapping screw that is invariably "cammed-out" at the factory; the only screw to be removed and you need vise grips to get it out. This is a stainless steel case so why not a stainless steel screw? The secondary leads are 12 gauge wire and since we use nothing but 10 gauge for main supply cable it always seemed odd but, I guess no more odd than the systems I've seen that feed 8 gauge from 12 or 10 gauge (!). This "bottleneck" does not seem to impair the unit's performance (the leads are only about 8" long) but how can you check with a fully potted coil? This particular unit will not mount on a 4"x4" post because the flanges used for mounting extend out of the sides (like ears) rather than from the top and bottom. Go figure. This very industrial looking unit (the mill finsih case looks a bit battle-scarred right out of the box) cleans up nicely with a green ScotchBrite(r) pad. The label, a quaint '50s look, is printed either on foil (the USA unit) or laser printed (Mexico) peels off quite cleanly with care (a separate code-required label on the side is not ugly) and the wiring label is inside the swing-down access cover. This is a hefty unit that would anchor a small dinghy so be careful when mounting on those stucco-over-styrofoam trophy houses prevalent in today's throwaway market. We trigger these items with a 12v/120v relay but that is another topic.

*Acme (800.334.5214) makes a bewildering number of transformers for low voltage outdoor lighting. They recently left me (my supplier) dangling over a quick ship because the computer inadvertantly ordered 4 of the SL which was back-ordered while they were sitting on thousands of SR types. Did you ever pay to have 4 500w transformers shipped overnight? The T-79105SL/SR is stainless steel; the T-1-79105SL/SR is mild steel painted grey and not significantly cheaper. This item is also available in 100w and 300w spec but they all pretty much look and cost the same. Acme Transformer, Lumberton, NC, a Division of Acme Electric Corporation is not affliliated with the Acme of Road Runner and Wiley Coyote fame.

[sitelights]

The Acme transformer reviewed in the previous post does not comply with the UL 1838 standard for low voltage outdoor lighting systems. There is no provision for overload protection on the secondaries (a thermal overload switch on the primary side does however turn the unit off if it overheats) and it allows a more than 300w lamp load. The manufacturer's statement about the ampacity of the secondary cable should be complied with under all circumstances.

[landscapelight]

I have a thought on these units, does the transformer come with any type of secondary fuse? I believe that all transformers no matter their purpose should have some form of built in secondary protection. It provides the contractor with piece of mind and the homeowner with safety. I believe that you can add secondary protection but for the first time installer most of them may not think of it.

[sitelights]

The Acme units do not have circuit breaker(s) on the secondary side but a dead short will cause overheating which will trip the thermal breaker (auto-reset) on the primary side. With a bit of effort the Acme P & S can be retrofited with secondary protection using automotive hardware to add a fusible link to the low voltage ie. secondary wiring within the case. Nightscaping used screw-in household fuses in their early transformers. The real danger lies in using a buck-boost without any protection. The buck-boost types are very cheap and I have seen many of them used on projects that I am called in to fix. UL 1838 has addressed this issue.

[landscapelight]

Have you seen the PX Series from FX Luminaire? We have just started selling them on the West coast and cannot sell them out of our designated territory(one things I wish other manufacturers would do too) and I have to say that they are one of the best thought out and well built transformers I have seen, big lugs, removable cover, UL1838 the whole nine yards. It may sound like I am trying to sell you one but I cannot, if anyone can find a distributor for fx in their local state it is well worth the time to look at one. It was a difference between night and day when I put one next to all the others, it is well built and strong.

[landscape liter]

Landscape light, interesting side note. The F/X transformer is UL 1838 certified not by UL but by ETL to UL 1838 specs. Some manufacturers like to play fast and loose with ambiguity when it comes to UL certification. I wonder why it doesn't carry the certification from UL. What I don't like about the unit is it's small wiring compartment, 120V photocell wires together with 12V ones. 120V terminal block in line with 12V ones. The latch is pretty flimsy to boot. Other than that it's a pretty nice unit like you said.