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I have 240v over Hot-Hot-Ground which is feeding to a sub-panel for a pool.
Sub-panel will have a 30amp 2-pole breaker for the pool pump and a 15amp breaker for the lights.

I need 120v for the pool lights, but I do not have a neutral.

I found a Square D 50SV1A step-down transformer which will convert the 240v to 120v and provide the needed neutral.
I am going to supply the transformer the 240v using a 2-pole 15amp breaker.

I need to bond the ground lug in the transformer to the ground in the sub-panel. In addition, I also need to bond the neutral leg from the transformer to the ground in the sub-panel.

Is this a correct way to get 120v neutral from 240v?
The answers to other questions suggest this type of fix is expensive, but the transformer is relatively inexpensive compared to opening the walls for new wires.
Can I pull 120v outlets from a 220v box with no neutral?
Case 4: Transformer and subpanel

Edit: (not enough reputation to answer comments)
I didn’t notice that the transformer was only 50w. The lights are about 500w and I’d be driving 2, so that isn’t going to work. I think the lights are about 30 years old. They are incandescent.

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    Um, that transformer is only good for 50 watts. It's barely larger than a $13 thermostat transformer which is 40 watts.
    – Harper - Reinstate Monica
    Jun 4, 2021 at 22:34
  • What are you using for pool lights? You'd be insane to be feeding 120V directly to them...any modern system is going to either run at ~12VAC or ~12VDC
    – ThreePhaseEel
    Jun 4, 2021 at 23:36
  • Is replacing the pool lights an option? It sounds like you have a quite obsolete and hazardous system that needs to be replaced for safety's sake...
    – ThreePhaseEel
    Jun 5, 2021 at 13:29

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20 years ago, you needed 120V in the US/Canada for lighting unless you went "industrial". That is absolutely not the case any more. (You do still need 120V if you want to have a standard convenience receptacle for ordinary household stuff.)

Most lighting now (or most that you should use anyway) uses LEDs. LEDs don't work on 120V. LEDs don't work on AC. They work on low-voltage DC. The result is that there are two types of lighting fixtures available (in most places) - some with built-in drivers (to get from high-voltage AC to low-voltage DC) and LEDs and others with ordinary sockets (e.g., Edison base) that accept LED "bulbs" that include drivers. All you need to do is find a fixture that is designed either for 240V or for a range (typically something <= 120V to something >= 240V). In a quick search I found one at Home Depot that states:

Multi-volt LED driver operates on any line voltage from 120-277-Volt

and I am sure you can find more without too much trouble.

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