Article 210.21(B) (2)

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donf

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I am preparing to teach a Commercial Services class this week. The topic, while not new to me, is one I have not had to teach in several years.

The last time I had to look at this code citation, it stated that a "Multi-outlet" branch circuit (cord and plug) could not be loaded to an amount greater than 80% of the OCPD. On a 20A circuit, the load could not be more than 16 Amps.

When I researched that using the 2017 code, I discovered that it reads, "...a receptacle shall not supply more than …." The 20 Amp receptacle lists 16 Amp in the table.

Here's my concern with my interpretation. As I read that citation, (in a commercial) environment, I could have several receptacles in a 20 amp circuit supplying loads of 12 Amps each, just for arguments sake, and still have a code compliant branch circuit.

I grant you that there is no way we can ever guarantee what load gets plugged into the receptacle, but am I reading and understanding this citation correctly?
 
It is saying that no one receptacle can supply a load over 16A on a multi receptacle circuit. IMO, one of the stupidest rules as there is no way to check or enforce it.
 
Well, let's look at 210.21(B)(2)
Total Cord-and-Plug-Connected Load. Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord-and-plug-connected load in excess of the maximum specified in Table 210.21(B)(2).

TABLE 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle
Circuit Rating (A) Receptacle Rating (A) Maximum Load (A)
15 or 20 15 12
20 20 16
30 30 24
Click to expand...

Notice this is for two OR MORE receptacles on the same circuit. Nothing is said of a MWBC but that wouldn't change anything. Note also that a duplex receptacle counts as two receptacles.

Now, if you only had one SINGLE receptacle on a dedicated circuit, a 15A receptacle on a 15A circuit could be loaded to 100%. Likewise a 20A receptacle on a 20A circuit could have a connected load of 20A.

-Hal
 
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hbiss said:
Well, let's look at 210.21(B)(2)


Notice this is for two OR MORE receptacles on the same circuit. Nothing is said of a MWBC but that wouldn't change anything. Note also that a duplex receptacle counts as two receptacles.

Now, if you only had one SINGLE receptacle on a dedicated circuit, a 15A receptacle on a 15A circuit could be loaded to 100%. Likewise a 20A receptacle on a 20A circuit could have a connected load of 20A.

-Hal
Click to expand...

Who mentioned a MWBC?
 
Little Bill said:
It is saying that no one receptacle can supply a load over 16A on a multi receptacle circuit. IMO, one of the stupidest rules as there is no way to check or enforce it.
Click to expand...

Well that's true. But for design purposes where you know the receptacles in an area might have large connected loads, like a kitchen countertop, keep it in mind. Don't go Code minimum with only two SABCs if you happen to know there are going to be several countertop appliances that draw close to 16A. If you need to justify the extra cost to the customer quote the Code article.

-Hal
 
"Well that's true. But for design purposes where you know the receptacles in an area might have large connected loads, like a kitchen countertop, keep it in mind. Don't go Code minimum with only two SABCs if you happen to know there are going to be several countertop appliances that draw close to 16A. If you need to justify the extra cost to the customer quote the Code article".

Hal, you just hit my point of confusion. You said, "​
if you happen to know there are going to be several countertop appliances that draw close to 16A". You are looking at the total load on the circuit. The code is saying, "A Receptacle" not the total load on the circuit, that's if I am correct in my understanding.

Supose the customer connects two 15 amp print stations on the same 13 receptacle 20 amp BC. Dumb, yes. But according to the veribage in 210.21 (B) (2) it is code compliant cicuit..​
 
Before you get to 210.21, you should back up to 210.19. That is where it tells us not to overload circuits.
 
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