"Works like a charm" as a former colleague used to say. I tested two 100-bulb strings and ran out of replacement bulbs, over a dozen "bum" ones at least! I made another trip to Rona (Walmart was sold out) to buy more replacements. My enthusiasm for putting up those outdoor lights has waned somewhat though. During the course of the day the temperature has plummeted from near 0°C this morning to -9°C this evening.