Code explanation for single 20a receptacle on 20a circuit

Just making sure I understand correctly, if you have a dedicated 20a circuit with one receptacle on it, code states that single receptacle has to be a 20a receptacle, correct? If so, why? I understand the theory (why run a 20a line if you only plan on pulling a max of 15a), but how is this a safety hazard? Why does code care about something such as this where there won't be anything potentially dangerous now or in the future (or am I missing the danger)? Seems like the only danger here is wasted money.

As a side note, if running a dedicated 20a circuit to a bathroom, it's code to have 2 15a duplex receptacles on the circuit, correct? One receptacle would be GFCI, with the other receptacle being downstream. Is there any added benefit to adding a 20a receptacle to the bathroom?

 

The thought is that if there is only one single place to pull power from on the circuit that it must be able to safely handle the load. A standard duplex receptacle counts as two places.

The receptacle requirements for bathrooms require a GFI protected receptacle within 36" of the outside edge of the bowl or bowls. More are allowed.

There is no benefit to using the 20 amp T-slot device. You will not find anything in a standard house that has the T-slots on the cord.

 

While I don't disagree and I'm merely asking questions to get a better understanding, doesn't this set a precedence that the user is purposely attempting to pull up to 20 amps of current out of a 20 amp circuit? If I want to run a dedicated 20a circuit for a 15a orientated window A/C unit, it would be against code to put a single (and only)15a receptacle on the circuit? The 20a circuit is merely insurance and for future upgrading, I don't see the safety issue, especially since any 15a orientated appliance shouldn't be pulling more than 15 amps. A 20a orientated plug wouldn't even fit into a 15a receptacle, so there's really no safety issue. Again, I'm not challenging, just attempting to gain an understanding.

 

Technically yes. The counter argument is why would you install a 20A breaker when it is only possible to pull 15A through the (weakest link) receptacle? The safer choice would be the smaller 15A breaker to protect the 15A load and receptacle.

It is a very minor one in the scheme of things. I'd probably even say it's more a consistency issue than safety.

 

I've seen a/c's, treadmills, copymachines, and something that I have no clue what it does have 20A plugs. A 20A receptacle has different contacts in it than a 15A receptacle, even a quality one. I have also had problems with a/cs on 15A breakers as when the compressor starts, the breaker would trip. Never have this problem with 20A breakers.