It's July. Short of living on a mountain top or within shouting distance of the Arctic circle no one in the northern hemisphere should be needing to use a 250 watt bulb for only a handful of chicks.
There is no set wattage to use for brooding. It all depends on your local ambient temperature, how many chicks you are brooding, the size of their brooder, and the nature of the airflow within it.
Go by the behavior of the chicks to determine if they are too hot or cold. They'll tell you what you need to know.
This is what you are looking for:
Chances are a 100w bulb or even smaller will get the job done for you. You'll soon figure it out.