while working on a remodel home I came across an outlet which had two seperate hot conductors with the tab still intact. I am an apprentice so I am learning. If each conductor were a seperate phase would the potential be 240VAC, and if they are the same phase would there be adverse effects if both sides of the outlet were being used. Thanks in advance.
improper half switced outlet?
- Thread starter kvl
- Start date
- Status
- Location
- Illinois
- Occupation
- retired electrician
Re: improper half switced outlet?
Don
The potential would be zero. This would be a bolted fault and open the OCPD (overcurrent protective device).
Don
charlie
Senior Member
- Location
- Indianapolis
Re: improper half switced outlet?
kvl, welcome to the forum.
If the tab were still intact, the only thing I can imagine is that the receptacle has a feed into it and out of it. In other words, the receptacle is used to continue the circuit and the tab is carrying the full circuit load of everything downstream from it. Anything else would be a dead short and nothing would work.
kvl, welcome to the forum.
If the tab were still intact, the only thing I can imagine is that the receptacle has a feed into it and out of it. In other words, the receptacle is used to continue the circuit and the tab is carrying the full circuit load of everything downstream from it. Anything else would be a dead short and nothing would work.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: improper half switced outlet?
</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Whether one or both receptacles are used doesn't matter. . . the total amount of the connected load does. I'll guess that what you saw was a 15 amp duplex receptacle. Also, I'll guess that two different 20 amp overcurrent protective devices (OCPD) had to be shut off before the receptacle was de-energized. 20 + 20 = 40 amps possible through one receptacle. That's a formula for a receptacle fire.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">I'll guess that the original installation was a multiwire small appliance circuit with two different 20 amp circuits connected to the duplex receptacle. I'll guess that someone replaced the duplex device with a new devuce and didn't understand the breakout tab. To stop the OCPD blowing, one OCPD was moved from its original bus to the same bus as the other OCPD. This sums the neutral current from the two circuits on the multiwire single neutral. That's a formula for a very hot neutral.</font>
charlie
Senior Member
- Location
- Indianapolis
Re: improper half switced outlet?
WOW! I had not even considered a miswired receptacle. Great catch Al.
WOW! I had not even considered a miswired receptacle. Great catch Al.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: improper half switced outlet?
Thanks Charlie.
It came to mind 'cause of a troubleshooting run that I made at a widow's home a few years back. The kitchen outlets were blowing circuit breakers.
The house had been rewired 30 years ago. Three duplex receptacles in the kitchen had been split wired on a 20 amp small appliance multiwire. . .two 20 amp small app circuits.
I found one circuit breaker tripped. I reset it, got a really sharp report and it tripped back, along with another breaker.
Then I noticed the original tripped breaker was not seated all the way down on the bus. I pulled it loose, and saw a lot of arc weld pits on the bus and that most of the contact on the breaker was burned away.
I analyzed the circuit and found a breakout tab on a duplex receptacle still intact.
The widow said hubby had replaced that one outlet 12 years ago and, until he died a year ago, had always taken care of the "mechanical things".
She had simply overloaded the one connected 20 amp breaker. When that breaker tripped on a running overload, she had reset all the breakers. When she came to the burned one, the one hubby had pretty much destroyed, her resetting it pushed it down enough to make contact, creating a 240 volt short and scaring the bejeebers out of her.
She actually kept the breakout tab after I removed it from the device!
Edit to clarify last sentence.
[ December 28, 2004, 02:00 PM: Message edited by: al hildenbrand ]
Thanks Charlie.
It came to mind 'cause of a troubleshooting run that I made at a widow's home a few years back. The kitchen outlets were blowing circuit breakers.
The house had been rewired 30 years ago. Three duplex receptacles in the kitchen had been split wired on a 20 amp small appliance multiwire. . .two 20 amp small app circuits.
I found one circuit breaker tripped. I reset it, got a really sharp report and it tripped back, along with another breaker.
Then I noticed the original tripped breaker was not seated all the way down on the bus. I pulled it loose, and saw a lot of arc weld pits on the bus and that most of the contact on the breaker was burned away.
I analyzed the circuit and found a breakout tab on a duplex receptacle still intact.
The widow said hubby had replaced that one outlet 12 years ago and, until he died a year ago, had always taken care of the "mechanical things".
She had simply overloaded the one connected 20 amp breaker. When that breaker tripped on a running overload, she had reset all the breakers. When she came to the burned one, the one hubby had pretty much destroyed, her resetting it pushed it down enough to make contact, creating a 240 volt short and scaring the bejeebers out of her.
She actually kept the breakout tab after I removed it from the device!
Edit to clarify last sentence.
[ December 28, 2004, 02:00 PM: Message edited by: al hildenbrand ]
karl riley
Senior Member
Re: improper half switced outlet?
And don't forget to break off the neutral tab also when you break off the hot one. Otherwise neutral current splits and goes back in two circuits. Big magnetic field. Heating.
Karl
And don't forget to break off the neutral tab also when you break off the hot one. Otherwise neutral current splits and goes back in two circuits. Big magnetic field. Heating.
Karl
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: improper half switced outlet?
Karl,
On a multiwire there is only one neutral.
Karl,
On a multiwire there is only one neutral.karl riley
Senior Member
Re: improper half switced outlet?
Right, Al. I read the postings too fast.
Karl
Right, Al. I read the postings too fast.
Karl
- Status