Hi Is it a problem to have a number of 20amp receptacles on a 20amp circuit-breaker like a number of 15amp receptacles on a 20amp circuit? Or should a 20amp circuit have only one 20amp receptacle? I have read numerous electrical books looking for this answer and not see it [if it is there] Thanks for your help. Frank
The only reading you need to do is NEC Article 210. Specifically Article 210.21(B) (1) which states that if there is only one receptacle on a 20A circuit it must be 20A. Also 210.21(B)(3) and Table 210.21(B)(2) which tell you you can use 15A receptacles on multiple outlet 20A circuits.
Hope this helps.
First, the one-socket rule: If a circuit powers one socket, and it‘s a one-eye "simplex", then the socket amp rating and breaker must match exactly, except for 40A.
The common plug found in American houses is a "duplex" - it has two sockets. Very important.
A 15, 20 or 30A circuit can have any number of same size sockets. *
There is a special exception in NEC that allows 15A sockets on 20A circuits. That is a mate to another regulation (in product safety codes, not in the NEC) that requires all 15A sockets must be rated for 20A passthrough.
That's how we get here. Remember the 1-socket rule still applies, so a lone 15A socket on a 20A breaker is no-go.
* There are other rules in NEC or building codes which, in some cases, limit how many receptacles you can have on one circuit.
Is it a problem to have more 20 amp receptacles on a 20 amp circuit?
No it is not a problem at all. With residential there is not a true limit to the number unless local jurisdiction limits the number. Most of the time only 15 amp outlets are used on 20 amp circuits with a minimum of 2 but usually many more. Most folks don't spend the extra on 20 amp outlets because when was the last time you actually saw a 20 amp cord connected device (fairly rare) with the exception of roasters or other large kitchen appliances so we use 15 amp outlets most of the time.