7 Tips for Choosing a Step-Down Transformer

Step-down transformers allow any electrical product to be installed on 347V circuits, which is why many electrical contractors keep a few in their car stock. Selecting the correct step-down transformer ensures the physical dimensions of the transformer are as small as possible to fit easily in the junction box while keeping costs as low as possible. Here are our tips on selecting the best step-down transformer for your job.

1) Check the input voltage on the electrical product.
While some electrical products accept only an input voltage of 120V, many take universal inputs of 120-277V. In the latter cases, selecting a step-down transformer that only brings the voltage down to 240V instead of 120V will mean a smaller transformer that costs less.

2) Minimize the transformer power where possible.
If your electrical product uses 40W, using a 50W step-down transformer is always better than using a 100W version. Once again, this makes installation easier since the transformer is smaller, and will cost less for the same result.

3) Verify the efficacy of your step-down transformer.
For example, Arani’s step-down transformers have an efficacy of 89%, meaning on a 50W transformer, you should not install a product of higher than ~44W. Always give a bit of safety allowance by not maxing out the effective power to ensure the transformer does not fail.

4) Check the physical dimensions of the box/housing as compared to the step-down transformer.
If your application does not have much room to house the transformer, the dimensions of the transformer are crucial to stay compliant to code. Refer to tips 1 and 2 to minimize the physical size of the transformer.

5) Keep the step-down transformers physically protected.
Step-down transformers consist primarily of coils of wire and magnets, and as such have an extremely low rate of failure. However, they are still susceptible to physical damage if left in unprotected environments.

6) When installing a lighting fixture, verify the dimming requirements of your application.
For 0-10V dimming, a step-down transformer will not affect the dimmability of a lighting fixture. However, for regular dimming, after installing a step-down transformer, the fixture will no longer be dimmable.

7) Calculate your total costs before assuming step-down transformers are right for your application.
While step-down transformers are convenient and effective, in certain cases, it may be cheaper to simply change the circuit voltage at the panel from 347V to 120V.

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