light, candlepower
燭 centers on a light source, specifically a candle or its light. The meaning 'candlepower' is an extension of that idea, referring to the brightness of a candle.
燭 combines 火 (fire) with 蜀, which likely contributes the sound. The character originally referred to a torch or candle, a light source using fire.
The left side is fire 火, and the right side 蜀 looks like a container with a wick. Picture a candle with a flame burning brightly.
For ソク, imagine a sock catching fire from a candle: sock -> ソク, and the candle's flame lights the sock.
candle
candlestick; candlestand
light; lamp
sea bilberry (Vaccinium bracteatum)
portable candlestick
candelabra; candelabrum; girandole
candlepower
holding a lamp in one's hand
bright light
wedding ceremony
wick of a candle
naked candle; uncovered candle; unshaded candle