Polarity - light socket

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hardworker

Senior Member
What does code say about porcelain light sockets and polarity? I notice the older sockets have the same color terminal screws. Unless you look closely, you will not know which terminal feeds the tongue and which one feeds the shell.

Please comment.
 

charlie b

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When screwing a light bulb in or out, especially when taking out a broken bulb, you want to keep your hand as far away as possible from the hot conductor. Normally, people don't turn off the circuit breaker just to replace a light bulb. And since the light is not working, it will be difficult to tell whether the switch is turned on or off. So if you got the wiring wrong and connected the hot wire to the shell, and if the light was turned on but the bulb broken, there would be a shock hazard to the person replacing the bulb.
 

Dennis Alwon

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Many people will actually be touching the shell of the bulb when unscrewing a bulb. If they touch the shell and are grounded they can get a shock if the switch is on.
 

hillbilly1

Senior Member
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North Georgia mountains
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Owner/electrical contractor
There are exceptions, but those have to do with HID fixtures (except Canada), but that is another subject that I do not believe your asking at this time!
 

kwired

Electron manager
Location
NE Nebraska
The shell does not have to be connected to a grounded conductor. If a grounded conductor is connected to the lampholder it must be connected to the shell.

410.90 Screw Shell Type. Lampholders of the screw shell type shall be installed for use as lampholders only. Where supplied by a circuit having a grounded conductor, the grounded conductor shall be connected to the screw shell.
 

hardworker

Senior Member
I understand the polarity issue and the reason code states the designated terminals screws. I see all new porcelain sockets have the terminal screws marked with black/white color or brass/white color. The porcelain sockets of the 50's and 60's had no designation.

I see these sockets still in use from that era and they may or may not be polarized correctly.

Apparently code did not rule this issue in that era.

Am I correct?

If so, when did the code change?
 

kwired

Electron manager
Location
NE Nebraska
Very correct as there are many 240 volt Mogul base lamps still in use and still available.:thumbsup:

There are 230 volt medium base lamps also. Then there is HID's that may have an ungrounded conductor connected to shell in both medium and mogul.
 

Dennis Alwon

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Location
Chapel Hill, NC
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The shell does not have to be connected to a grounded conductor. If a grounded conductor is connected to the lampholder it must be connected to the shell.

The question was reverse polarity. Of course, it doesn't matter with a 240V socket but then we would not have reverse polarity. I answered the question given.
 

kwired

Electron manager
Location
NE Nebraska
The question was reverse polarity. Of course, it doesn't matter with a 240V socket but then we would not have reverse polarity. I answered the question given.

The words "reverse" and "neutral" or "grounded" are not in the OP or any posts that he followed up with:p
 

Dennis Alwon

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The words "reverse" and "neutral" or "grounded" are not in the OP or any posts that he followed up with:p

So he was asking about polarity of a 240v circuit-- come on- you really are being contrary here. The fact is he talks about the color screw, which one feeds the shell, and polarity. I guess I was way off base.
 

kwired

Electron manager
Location
NE Nebraska
So he was asking about polarity of a 240v circuit-- come on- you really are being contrary here. The fact is he talks about the color screw, which one feeds the shell, and polarity. I guess I was way off base.

Don't take it so seriously. Just trying to enlighten those that may not realize there isn't necessarily a grounded conductor run to all lampholders, the :p was just for a little fun, it does have a smile after all, if I was attacking you I could have used the:dunce:. :angel:

I think OP's question was still answered here.
 

hardworker

Senior Member
Does anyone know when the code changed? I think it would be interesting to know the year. I am guessing in the 60's ??

Any code historians out there?
 

480sparky

Senior Member
Location
Iowegia
The screw-shell requirement goes back to at least back to 1937 (Art 2008.g). The NEC was renumbered in that addition, so finding it before that may prove tricky, if it pre-dates '27.
 

ActionDave

Chief Moderator
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Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
If I could find my 1923 I would. Even worse, I have 2!!!!:weeping:
Hang on there you. Leave the code history to 480. You stay on grammer, which by the way you have been slacking on. I know because you have not been correcting any of my post and I have been intentionally been misusing "there" when it should have been "their".
 
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