Transformer Tip - 12v Light


line in the header graphics


Pool Gallon Calculator

Liquid Calculator


Chemical pH Chart



Salt Levels for Pools

Sand Qty For Filters

Stabilizer Levels


Industry Terminology


MSDS Data Sheets

Product Support

Balboa Ref Cards

Error Codes - Balboa

Error Codes - Others

Manuals / Installation


Heater Element Ohms

Thru-bolt Types

Transformer Tip


12 Volt Light Transformer, Wire Identification Tip


   This tip addresses how to identify the wires running in and out of a unmarked 12volt AC light transformer. It does not attempt to educate you on transformers, spa lights, electricity or how to use or read a electrical meter.

        It is critical that a transformer be wired correctly. If a transformer is wired backwards it will burn up. A spa light transformer takes voltage from a incoming power source, let's say 115 volts or 230 volts and steps-down that voltage so it can be used to operate a low voltage light bulb, lets say 12 volts. A transformer normally has two wires coming into one side of the transformer and two wires coming out of the transformer on the opposite side.

    The question at hand is, which two wires are hooked to the incoming power source and which two wires should go to the spa light?

By using your test meter and testing for Ohms, you can determine the answer. The pair of wires with the highest Ohms reading are the wires which are to be connected to the incoming power supply. The smaller Ohm reading are the pair of wires which will run to the spa light. Do not concern yourself with the actual Ohm reading, it will vary from transformer to transformer, just remember, the pair of wires with the highest Ohm reading connects to the power source.


Left pair of wires test out at

 K Ohms
(to power)

     Right pair of wires test out at 
 K Ohms
(to light bulb)

Also Note that where each pair of wires come out of the transformer does not determine which connects to power or which connects to the spa light.



Sorry, we are not a retailer. We sell wholesale to businesses associated with the Pool / Spa and Water Industries only.

2015 H2O Company Inc.