Low Voltage lighting / transformer question

Factual Questions
1

6 fixture, containing 1 18W (12v) bulb each, no plan to add more.

Do I just add the wattage of all 6 bulbs (108 total) and get transformer rated that high, or higher?

For example, is this enough capacity?

Intermatic 121W Timer/Transformer for $31.49

Features include:
Powers all 12V Lighting systems up to 121W
Fully Programmable timer w/ two sets of on/off trippers
Heavy Duty Polymer Construction
Not Suitable for Use with Submersible fixtures or products

Technical Specifications:
121 Watt Timer
2 Sets of Trippers

All labeling of existing Intermatic transformer missing. It buzzes like crazy, always have and I want to replace it.

2

121 watt unit would be about right. To large and you waste power. To small and the transformer gets damaged.

You add all the bulb wattage together for 108 watts. Add about 10% for a good buffer amount. You get 118 watts for target size of the transformmer.

3

Thanks for the advice.

4

Yeah, your proposed transformer will do the job. If I were doing it for myself I would go the next larger size though. You say you don’t intend to add to the system. I’ll lay odds you will want to at some time.

One thing you might check on the nameplate data. Do they give a temperature rise? That’s the rise at full load and it shouldn’t exceed about 40 C.