| (1) Single Receptacle on an Individual Branch Circuit. A single receptacle
| installed on an individual branch circuit shall have an ampere rating not
| less than that of the branch circuit."
| A 20 ampere receptacle cannot be installed on a 30 ampere individual branch
| circuit when it is the only receptacle. Every dryer circuit that I have
| seen in many years is on an individual branch circuit.
| Exceptions do not apply.
But if it is NOT the ONLY receptacle, then it isn't an exception, as the
rule you quote specifically does not apply.
If a receptacle is constructed with the ability to handle a total of 40
amps between the 2 NEMA 5/6-20R outlets, it seems it would be connectable
with up to 40 amp OCP, assuming the wiring handles it, too. You could
plug in 2 separate appliances using 16 amps each (under the 80% rule) and
pull 32 amps, if the OCP is 40 amps.
We already allow 15 amp devices on a 20 amp circuit because the devices
really are rated 20 amps anyway. The 15 is just the plug configuration.
So as long as the receptacle device and the wiring to it can handle it,
what is the TOTAL branch circuit amperage limit involved?
So back to the OP's idea. He wants to make that 30 amp branch circuit
have TWO outlets, a 10-30R and a 6-20R. How is the rule violated.
Suppose his circuit was already 4-wire (e.g. separate ground properly
wired in) with a 14-30R for the dryer. Could he now connect a 6-20R
on the same branch circuit? How is the rule violated if not?
|> The question of the ground vs. neutral is a question of semantics, not
|> safety. In the case of the dryer outlet reguardless of what you call it,
|> this is a single wire that connects back to the ground/neural bus in the
|> service entrance panel and nothing else.
| The ground verses the neutral is not a question of semantics, and is
| precisely a question of safety. First off, residential 240/120 volt
| circuits do not have a neutral but a grounded conductor.
It's certainly not neutral if there is voltage present due to an
| Secondly, the grounded conductor is for carrying current under normal
| operating conditions. The equipment grounding conductor is for carrying
| current under abnormal conditions. They serve two entirely different
| functions and have two entirely separate sets of safety rules in the NEC..
|> In this particular case the last post from the person asking the
|> question indicates that there may be an air conditioning compressor
|> piggybacked onto the dryer circuit. If this is the case *that* is
|> illegal and needs to be resolved.
|> Pete C.
| What is illegal about it? (Your turn)
I don't know what he is referring to. There seems to be a perception
that the dryer must have a dedicated branch circuit. I don't know that
this is the case at all. I don't know what rule would apply. Doing
load calculations could consider that the dryer and compressor will
intentionally never be used at the same time ... is that a valid way
to do the load calculation? If so, then piggybacking them together
might be fine, if the 30 amp OCP on 6-20R and the grounded conductor
issues were resolve.
This would have been an entirely different thread had the OP had a 4-wire
branch circuit and 14-30R on the dryer and wanted a 2nd 14-30R or 6-30R
for the compressor that was designed to be connected to a 30 amp circuit.
| Phil Howard KA9WGN | http://linuxhomepage.com/ http://ham.org/ |
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