ECN Forum Forums General Topics of the Trade General Discussion Area 15Amp GFCI on 20Amp Circuit?

No offence taken - I should get a copy of the NEC for reference.
I find it odd that the NEC allows this? Can you use a 20amp receptacle on a 30a circuit, or a 30a receptacle on a 40a circuit? Or is there a code just for the t-slot GFI's.
Can you use regular 15amp receptacles on a 20amp circuit? Can you use t-slots on a 15amp circuit?