120 VAC socket and switching question

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Discussion Overview

The discussion revolves around questions related to 120 VAC sockets, specifically focusing on the identification of hot and neutral pins, the appropriate wiring practices for AC connections, and the specifications for AC socket modules used in monitors and PCs. The scope includes technical explanations and practical applications related to household wiring and embedded projects.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Experimental/applied

Main Points Raised

  • One participant inquires about the identification of hot and neutral pins on AC sockets found on monitors and PCs.
  • Another participant clarifies that on a standard 3-prong AC socket, the narrower hole is the hot and the wider hole is the neutral, suggesting a visual analogy to help remember this.
  • There is a discussion about the IEC 320 socket module and how to verify the hot and neutral configuration using a multimeter.
  • Some participants mention that different colored terminals are often used to distinguish hot and neutral connections in sockets with screw terminals.
  • There is a question regarding whether to switch the hot or neutral wire when controlling a light bulb with a relay, with multiple participants asserting that the hot should be switched to remove power completely from the circuit.
  • One participant expresses uncertainty about their previous assumption regarding the wider pin being hot and confirms their understanding of the correct configuration.

Areas of Agreement / Disagreement

Participants generally agree that the hot wire should be switched in a circuit and that the wider terminal is the neutral. However, there is some uncertainty expressed by participants regarding the identification of hot and neutral in different contexts, and no consensus is reached on all points raised.

Contextual Notes

Some participants note that their understanding is based on common practices and may vary depending on specific socket designs or manufacturer conventions. There is also mention of a specific application for an embedded project, indicating that the discussion may have practical implications beyond standard household wiring.

Sparky_
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Greetings –

I have 5 (somewhat related) questions –

1) Regarding the AC “socket” with the male pins that are on the back of most monitors and PCs – which pin is the hot and which is the neutral?

2) I could plug an AC cord up to the socket and if I do this – on a standard male plug that plugs into a wall outlet which of those 2 pins are the hot and neutral?

3) essentially the same question as 2) on an AC plug that plugs into the wall that has 1 pin that is slightly wider than the one beside it (that won’t plug into the female side of Christmas lights  ) is the slightly wider pin the hot?

4) How do I call out the simple AC socket found in the back of monitors and pcs? I have searched digi-key and thus far the closest I’ve found is a module with the socket but also with a switch and fuse for around 8 to 9 dollars. I would like the simple socket for cheap.

5) If switching something on 120 VAC household wiring – light bulb for example – would you switch the hot or the neutral? I’m guessing the hot.

Thanks
Sparky
 
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Sparky_ said:
Greetings –

I have 5 (somewhat related) questions –

1) Regarding the AC “socket” with the male pins that are on the back of most monitors and PCs – which pin is the hot and which is the neutral?

2) I could plug an AC cord up to the socket and if I do this – on a standard male plug that plugs into a wall outlet which of those 2 pins are the hot and neutral?

3) essentially the same question as 2) on an AC plug that plugs into the wall that has 1 pin that is slightly wider than the one beside it (that won’t plug into the female side of Christmas lights  ) is the slightly wider pin the hot?

4) How do I call out the simple AC socket found in the back of monitors and pcs? I have searched digi-key and thus far the closest I’ve found is a module with the socket but also with a switch and fuse for around 8 to 9 dollars. I would like the simple socket for cheap.

5) If switching something on 120 VAC household wiring – light bulb for example – would you switch the hot or the neutral? I’m guessing the hot.

Thanks
Sparky

It's called an IEC 320 socket module:

http://www.google.com/images?hl=en&...cket+module&gbv=2&aq=f&aqi=&aql=&oq=&gs_rfai=

On the standard 3-prong AC socket (the female, like on a power strip), the narrower hole is the Hot, and the wider hole is the Neutral. If you look at the socket and it looks like a face looking at you, the face's right eye is the wider Neutral, the face's left eye is the narrower Hot, and the mouth is the ground hole.

I'm not sure how this translates to the IEC 320 socket module, but you can beep out a 3-prong power cord (that ends in the female IEC 320 connector) to be sure. You may be able to find the Hot/Neutral spec in the IEC 320 socket module datasheets as well.
 
Thanks

Yes I can buzz out the socket with a cable plugged up to it.

(I guessed wrong - I guessed the wider would be the hot.)

Thanks for the part number also!
 
if the socket you get has screw terminals, a common way makers distinguish hot and neutral is different colored terminals. the hot will be darker than the neutral (usually copper finish vs aluminum finish). if not i would just wire it so that if you are looking at it head on with the ground (middle offset prong) down, the hot on the left and neutral on the right (inverse of your wall outlet).
 
Regarding which to switch -

would you switch the neutral or the hot - say through a relay going to a light bulb?

Thanks again
 
The wide terminal is the neutral. And you always want to switch the hot leg which removes the power completely from the circuit.
 
Also, the live leg should be the fused one, for the same reason.
 
dlgoff said:
The wide terminal is the neutral. And you always want to switch the hot leg which removes the power completely from the circuit.

Thanks!

(sort of what I thought but wanted to be sure). I have nto done many household wiring projects.

This is not for the house - I have a little embedded project where I will have a 120 VAC light bulb turn on and off as a demonstration.

Thanks again - very helpful
 
Sparky_ said:
Thanks

Yes I can buzz out the socket with a cable plugged up to it.

(I guessed wrong - I guessed the wider would be the hot.)

Thanks for the part number also!

sparkey said:
if the socket you get has screw terminals, a common way makers distinguish hot and neutral is different colored terminals. the hot will be darker than the neutral (usually copper finish vs aluminum finish). if not i would just wire it so that if you are looking at it head on with the ground (middle offset prong) down, the hot on the left and neutral on the right (inverse of your wall outlet).

Yikes! We have two Sparkys! :bugeye:
 
  • #10
its an invasion, look out!
 
  • #11
sparkey said:
its an invasion, look out!

:)

You will be assimilated

Resistance is futile –

(unless it’s less then 1 ohm)

Thanks again for the advice
 

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