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In the US, wall sockets deliver an electric potential difference or nominal voltage of 120V. Large machines, like refrigerators and washers, require standard line voltages and are plugged directly to power outlets. However, some electronic devices run on voltages much lower than the standard line voltage. To operate safely, they need to be attached to a low voltage transformer, which transfers and decreases the electric potential from one circuit to another.
Laptops, video cameras, and cellphones have low voltage transformers built into their chargers or power supply cables. On the other hand, lighting fixtures, doorbells, and thermostats must pass through low voltage transformers, which can either be hardwired in the circuit or plugged into a wall socket.
If you’re thinking about lighting up your garden or installing dimmable bulbs to your deck, make sure that your transformer meets all of your project’s power requirements. But how do you choose the best low voltage transformer that will work for your setup? Read our guide below to know how.
 |  |  |  |  | |
|---|---|---|---|---|---|
| Brand | Best Pro Lighting | Malibu C | Vista Pro | Lightkiwi | Light Tech |
| Output power type | AC | AC | AC | AC | AC |
| Tap type | multiple | Single | Single | Multiple | Single |
| Output voltage (Volts) | 12, 13, 14, 15 | 12 | 12 | 12, 13, 14, 15 | 12 |
| Size or capacity (Watts) | 300 | 300 | 300 | 300 | 150 |
| Exterior material | Stainless steel | Heavy-gauge plastic | Stainless steel | Stainless steel | Aluminum |
| Has dimming capability | ✖ | ✖ | ✖ | ✖ | ✓ |
| Has a photocell sensor | ✓ | ✓ | ✖ | ✖ | ✖ |
| Has a timer | ✓ | ✓ | ✓ | ✖ | ✖ |
| Warranty | Lifetime | 1 year | Lifetime | None | None |
| Our review | Review | Review | Review | Review | Review |
| Where to buy |
Choosing the Best Low Voltage Transformer
After designing the layout for your system, the next step is to find a low voltage transformer that matches it. To do that, you’ll have to consider the following aspects:
Size or capacity
The transformer’s size should always be greater than the total wattage of your lighting system. It is expressed in watts.
To compute the total wattage of your lighting system, take the sum of the wattage of all fixtures then add 10% allowance for voltage drop in the cables. You may go for a higher wattage than what your system requires but make sure that it doesn’t exceed 33%.
Power type
Verify the power input required by the bulbs and other fixtures in your system—whether AC or DC. Choose a transformer with the same power output type.
Low voltage transformers with AC output power typically have high capacity. For this reason, we recommend AC transformers for large landscape lighting projects. Most new models are built with timers or photocells that can be set to turn lights on and off automatically.
On the other hand, DC transformers are generally smaller both in physical size and capacity than AC transformers. They are best suited for LED lights which have low wattage. Most DC low voltage transformers work in tandem with dimming accessories to add special effects to your outdoor installations.
Type of outlet taps
Outlet taps or connectors can either be simple or multiple. Simple-tap transformers (also called single-tap) provide the same output voltage in all the taps on a strip (say, all taps supply 12V). Multiple-tap transformers have taps for a range of low voltage outputs, say 12V to 18V. Connect fixtures that are farther away from the transformer to the taps with the higher voltage to compensate for the voltage drop in long cable runs.
Safety features
The best low voltage transformers will have adequate safety features, including short circuit protection and thermal detection features. The transformer’s enclosure or box should be weather-proof and, possibly, lockable to protect from tampering.
Timers and photocells
These two features add convenience and functionality to your device. With the timer, you will be able to set the time for the transformer to turn on and off. With the photocell sensor, the device will be able to detect dusk and dawn and turn on or off accordingly. If they’re not part of the package, at least there should be ports for upgrading in the future.
Removable photocells are sometimes preferred over fixed types especially if you need to install the transformer where it’s difficult to detect dusk or dawn. This way, the photocell can be wired away from the box to where it can optimally detect ambient light.
Top 5 Best Low Voltage Transformers
1. Best Pro Lighting Low Voltage Transformer
- Output power type: AC
- Tap type: multiple
- Output voltage (Volts): 12, 13, 14, 15
- Size or capacity (Watts): 300
- Exterior material: Stainless steel
- Has dimming capability: No
- Has a photocell sensor: Yes
- Has a timer: Yes
- Warranty: Lifetime
Best Pro Lighting’s low voltage transformer is a toroidal magnetic transformer, which is typically the quietest and most durable of all types. It has a photo eye sensor to automatically turn the lights on at dusk and off at dawn. You may choose to override this auto on/off feature with the built-in timer. A digital display makes setting quick and easy. Look no farther for the best low voltage transformer. This Best Pro Lighting transformer will be perfect for all your indoor and outdoor low voltage lighting applications. It works for both LED and halogen bulbs.
- Easy to mount
- Setup is simple
- Has a solid build
- Very quiet
- Great timer flexibility
- Weather-proof
- UL-listed (UL 1838)
- Quite heavy
- Instructions are poor
- Can get hot
- Difficult to mount on a post
- Cannot be used with submersible fixtures
- Cannot be used with dimmers
2. Malibu C Outdoor Transformer
- Output power type: AC
- Tap type: Single
- Output voltage (Volts): 12
- Size or capacity (Watts): 300
- Exterior material: Heavy-gauge plastic
- Has dimming capability: No
- Has a photocell sensor: Yes
- Has a timer: Yes
- Warranty: 1 year
This low voltage transformer from Malibu C is fully equipped with a photo-eye sensor that turns it on at sundown and off at sunrise. Not only that, but it also has a timer that works with the photocell to tailor the automatic on/off feature to your requirements. For instance, you can set it to turn on at dusk and turn off at 4, 6, 8, or 10 hours later. You may also program the exact time you want it to turn on and off.
- Can be used with submersible fixtures
- Easy to install, program, and use
- Photocell connects with a removable wire
- Equipped with a digital timer
- Runs cool
- Heavy-duty
- Has many on/off timing options
- ETL-listed (UL 1838)
- Cannot be used with dimmers
- For outdoor use only
- Outputs 12V only
- Does not have a circuit breaker
- Needs to be plugged into a GFCI receptacle
- Quite noisy
3. Vista Pro Low Voltage Transformer with Mechanical Timer CTS 300T
- Output power type: AC
- Tap type: Single
- Output voltage (Volts): 12
- Size or capacity (Watts): 300
- Exterior material: Stainless steel
- Has dimming capability: No
- Has a photocell sensor: No
- Has a timer: Yes
- Warranty: Lifetime
Vista Pro’s low voltage transformer is designed for use in landscape lighting projects, but it can also be installed for pools and spas. Its exterior is durably constructed of gauge 20 stainless steel, smudge-proofed with powder coating, and sealed from moisture and debris.
- Has multiple 12V connectors
- Suitable for pool use
- Can be used with submersible fixtures
- Has louvered vents to prevent heating up
- UL-listed (UL 1838)
- Water-resistant casing
- Lockable latch
- Equipped with auto thermal shutoff
- Slightly noisy
- Not ideal for long cable runs
- Quite expensive
- Timer is not as accurate as the digital type
- Cannot be used with dimmers
- Not equipped with photocell sensor
4. Lightkiwi W9715 Low Voltage Transformer
- Output power type: AC
- Tap type: Multiple
- Output voltage (Volts): 12, 13, 14, 15
- Size or capacity (Watts): 300
- Exterior material: Stainless steel
- Has dimming capability: No
- Has a photocell sensor: No
- Has a timer: No
- Warranty: None
This multi-tap low voltage transformer is from Lightkiwi, a reputable company specializing in landscape lighting devices. Lightkiwi’s W9715 transformer is suitable for both indoor and outdoor applications. Like most quiet and long-lasting low voltage transformers, W9715 has a toroidal magnetic core. It is sturdily built of stainless steel and has ports for a timer and a photocell sensor.
- Has built-in circuit breaker
- Suitable for indoor and outdoor use
- Operates quietly
- Outputs up to 15V for long cable runs
- Has a locking latch
- ETL-listed
- A timer is not included
- A photocell is not included
- Has many sharp edges
- Wobbles because there’s only one attachment point
- Has no warranty
- Maximum load is only 70%
5. Light Tech LET-151 Electronic Low Voltage Transformer
- Output power type: AC
- Tap type: Single
- Output voltage (Volts): 12
- Size or capacity (Watts): 150
- Exterior material: Aluminum
- Has dimming capability: Yes
- Has a photocell sensor: No
- Has a timer: No
- Warranty: None
So far, we’ve featured magnetic low voltage transformers that are not designed to work with dimmers. If your project includes a dimming device, you may want to consider Light Tech’s LET151, an electronic low voltage transformer. It is small in size and easy to conceal or tuck away in tight spaces. If your installation requires something like that, then look no farther. LET151 could be what you’re looking for, so check out its specs which are listed below.
- Can be used with a dimmer
- Has an auto-reset short circuit protection
- Has an auto-reset thermal cutoff
- UL and cUL-listed
- Water-resistant
- Solid build
- Not suitable for LED bulbs
- Must be hardwired not plugged to an outlet
- Will not work if the load is less than 50W
- Must not be exposed to direct heat or sunlight
- Loads must be within 25 feet of the transformer
Conclusion
Finding the best low voltage transformer is relatively simple if you have a working knowledge about this device and you know what your design requires. If you need something quiet, long-lasting, and with high load capacities, then choose the magnetic toroidal type. Magnetic transformers, however, tend to be large and must be mounted on walls or posts. Massive landscaping lighting systems utilize commercial type magnetic transformers.
If you prefer something small and one that you can conceal behind plants or underground, we recommend electronic low voltage transformers. Dimmable transformers are of this type. Take note, though, that they have low wattage and are heat-sensitive. You must also locate them away from direct sources of heat. Electronic low voltage transformers are generally cheaper than their magnetic counterpart but are not as long-lasting.
As mentioned earlier, the total design load must be less than the wattage of the transformer that you’re going to buy. Even for the best low voltage transformers, the rule of thumb is to never load up to 100% of the maximum capacity rating. Check the product details and specs for the percentage of allowable load. Different brands and models will have a different limit, but it’s usually within 70%-80% of the transformer’s capacity rating.
Transformers won’t always work for all types of bulbs and fixtures. Light Tech’s LET151, for instance, won’t work for LED lighting. The reason for this is that most LEDs have very low wattage. If the total load does not reach the minimum load required, the transformer will not work properly. Some fixtures also have built-in transformers, in which case, you won’t need transformers for them.
There you have it—our brief guide and review of the top 5 best low voltage transformers that you can buy for your lighting projects.
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