Subject: Switched receptacle. For reasons unnecessary to go into the engineer shows a switched receptacle in a being fed from 2 separate circuits (not a mulit-wire branch circuit, but 2 separate 12/2 circuits; the hot and neutral tab on the receptacle will be removed). The circuits ordinate in separate panels. I told the engineer this was not legal but can?t find where it is against the NEC. Is this a violation, and if so, what section? Thanks!!
Switched receptacle
- Thread starter wyboy
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This is from NEC 2011
210.7 Multiple Branch Circuits
Where two or more branch circuits supply devices or equipment on the same yoke, a means to simultaneously disconnect
the ungrounded conductors supplying those devices shall be provided at the point at which the branch circuits originate.
210.7 Multiple Branch Circuits
Where two or more branch circuits supply devices or equipment on the same yoke, a means to simultaneously disconnect
the ungrounded conductors supplying those devices shall be provided at the point at which the branch circuits originate.
hillbilly1
Senior Member
- Location
- North Georgia mountains
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- Owner/electrical contractor
Being fed from two different panels would make it hard to comply with 210.7. If it was two seperate, single receptacles, not on the same yoke, but can be in the same box, then it could legally be done
iMuse97
Senior Member
- Location
- Chicagoland
Why would they even need to be the same box? Is it one of those cases where one can be supplied by a Standby Power source? Just install separate yoke devices and be done with it. That's why engineers sometimes get a bad rep: Some of them never read the code, much less understand it. 
(With due regards for all our fellow engineers on this forum.) I had one thinking about sizing #6 wire for a 30A/277V run, because it was 225 ft.?? The concern was magnified because once (s)he had been caught with too small a wire for the load and the distance, so apparently now everything has to be oversized.
(With due regards for all our fellow engineers on this forum.) I had one thinking about sizing #6 wire for a 30A/277V run, because it was 225 ft.?? The concern was magnified because once (s)he had been caught with too small a wire for the load and the distance, so apparently now everything has to be oversized.And the OP has to comply with 406.5(G)
Voltage Between Adjacent Devices.
A receptacle shall not be grouped or ganged in enclosures with other receptacles, snap switches, or similar devices, unless they are
arranged so that the voltage between adjacent devices does not exceed 300 volts, or unless they are installed in enclosures
equipped with identified, securely installed barriers between adjacent devices.
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
The OP said 12/2 which would be normally 20A 120V and 406.5(G) (2011) 406.4(G)-2008) wouldn't apply here because he would not be exceeding 300V between devices.
I am not sure on this so please correct me if i am wrong, :? if we have two separate circuit we could potentially have 240V between the conductors. And with 240 V doesn't that mean that we may have a peak to peak measurement of 339 Volts?
Twoskinsoneman
Senior Member
- Location
- West Virginia, USA NEC: 2020
- Occupation
- Facility Senior Electrician
I pretty sure the code never deals in peak voltages.
NEC def
Voltage (of a circuit). The greatest root-mean-square (rms)
(effective) difference of potential between any two conductors
of the circuit concerned.
Switched receptacle
This is more of a question than actual knowledge, wouldn't the rating of the receptacle come into play?
I know that when you break the tabs that only 120v will be going through each receptacle but unless the two circuits are on the same phase you would be getting 240 volts. If the receptacle is rated for 120v then wouldn't this be a violation?
This is more of a question than actual knowledge, wouldn't the rating of the receptacle come into play?
I know that when you break the tabs that only 120v will be going through each receptacle but unless the two circuits are on the same phase you would be getting 240 volts. If the receptacle is rated for 120v then wouldn't this be a violation?
A duplex receptacle is two receptacles on one yoke, neither receptacle will have more than its rated voltage.
210.7 is the deal breaker for the engineer
Roger
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Thanks Twoskins..., that would have been my answer. BTW, I wasn't implying that the installation that the engineers wanted in the OP was compliant, just that the adjacent voltage rule (300V) didn't apply.
copper chopper
Senior Member
- Location
- wisconsin
do this
do this
just put in 2 single recepticales in a 2 gang box.
do this
just put in 2 single recepticales in a 2 gang box.
captainwireman
Senior Member
- Location
- USA, mostly.
UL listing
UL listing
I am certain the UL listing would come into question here.
UL listing
I am certain the UL listing would come into question here.
That's why engineers sometimes get a bad rep: Some of them never read the code, much less understand it.
I also calculate #6 AWG wire is required for a 225-foot run of a 30 amp circuit, assuming VD was being limited to a maximum of 3% and conductors are copper.
CM = 2 x K x I x D/VD
K = 12.9 ohms
I = 30 amps
D = 225 feet
VD = 277*.03 = 8.31 volts
CM = 2 x 12.9 x 30 x 225/8.31 = 20956.7 cmils.
A #8 AWG conductor has an area of 16510 cmils, which would result in a 10.5 volt drop (3.8%). The #6 conductors result in a 6.6 volt drop (2.4%).
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