Change the ceiling light and it's not as bright.

I changed ceiling lights in a bed room and in a hallway.

When I flick the switch, they actually take time to get bright. Especially the one in the hallway, takes about a sec to actually get turned on after I flick the switch. They are very dimmed for the first a couple of minutes, then finally gives out full brightness....

I checked the voltage and it's only about 18.7v...shouldn't it be full 110V just like regular electrical outlets?? (I'm in Canada by the way..)

Please help me and thanks in advance!!

Allen