Please use voltage divider because esp8266 use 3.3V and you transmite from arduino 5V.
If you use adator in one line with the bulb, when the bulb on, the adaptor voltage rise more then 5V.
It can burn your esp8266.
It happend to me when I try using remote switch that use adaptor the same line with the bulb. The capasitor exploded.
So use separate line between adaptor and bulb, and use voltage divider.