brightidea
Member
- Location
- Ontario Canada
Is it called a ?U? ground plug or a three pronged plug and/or receptacle?
Since I have been alive and from what I have noticed at least in my area, most 120 volt 15 amp receptacles are placed in the position with the ground prong towards the bottom, looking at it from the front it could somewhat resemble a frowned face, that is an inverted U-ground towards the bottom.
In Canada we have the ULC/CSA pictorial diagram in our code book, ( I?m not sure with the NEC) with the ground at the top U-ground up, but almost all installations are with the U ground down below the Hot and Neutral prongs entering the receptacle actually resembling an ?n? rather than a ?u?.
When I took my masters course the debate arose, and the class was divided on which way a 120v/15A receptacle should be placed, ground up or ground down.
A reasonable explanation was given, ground on top because it is safer than the ground on the bottom. If anything fell in contact with a plug that is partially engaged/energized and partially disengaged/exposed, that objects falling by gravity would hit the ground prong first. Evidentially the code book shows the UL-ULC/CSA diagram as a ?u? ground and not an ?n? ground.
For the horizontal position the recommended safest way to install receptacles is to have the grounded neutral conductor on top with the wide flat prong over the narrow flat prong which is connected to the live conductor. The provided explanation used the same reasoning as above; in the case of accidental contact with energized and exposed prongs.
Also, in the vertical position with the ground at the bottom, using polarized plugs, the neutral prong is positioned slightly higher than the hot prong because the neutral is wider than the hot. So it is also more probable for falling objects to come into contact with the neutral first, but can still cause a short circuit across both prongs.
The rest of the class stood by the, stay with what is common, and continue to do what was done in times past, as most installers have the ground at the bottom. The way they have always ever done or most commonly seen.
Perhaps this could be a result of one the first journeyman electricians that figured the most logical way to install them was to have receptacles look like the face of a person, with the two prongs being eyes, and the third as the nose and mouth. Or he thought the ground should point towards the ground. GROUND to GROUND?
I?m not sure and I don?t know, I can only speculate at this time. I am curious to know such history and the true story of the receptacle. If I don?t find out soon, I won?t sleep properly at night. Please help me, or I will be forced to surf the web endlessly until I find it, and my wife will end up pulling the plug. One way or another, and in more than one way, let?s share our knowledge. I have heard there is more than one way to skin a cat.
Trivia Time. Do you know?
What are the metals used for the green grounding screw, the white wire screw and the hot wire screw? Anyone with knowledge in metallurgy?
How about the materials specifications and dimensions for the most common receptacle in the world? Who makes it and how many are sold world-wide each year?
When u get into 90 degree plug heads, it could be decided which way is best depending on your cord routing, from my experience in most cases the 90 degree head should be down with cord towards the ground, leaving the ?u? ground as an ?n? ground viewing it with your head up over your shoulders and two feet on the ground.
I believe that at least in North America that the Electrical manufacturers association is standardized on this issue, but there does seem to be some controversy to ground up or ground down.
Finally, is it ?u? or ?n??
By,
Bright Idea
Since I have been alive and from what I have noticed at least in my area, most 120 volt 15 amp receptacles are placed in the position with the ground prong towards the bottom, looking at it from the front it could somewhat resemble a frowned face, that is an inverted U-ground towards the bottom.
In Canada we have the ULC/CSA pictorial diagram in our code book, ( I?m not sure with the NEC) with the ground at the top U-ground up, but almost all installations are with the U ground down below the Hot and Neutral prongs entering the receptacle actually resembling an ?n? rather than a ?u?.
When I took my masters course the debate arose, and the class was divided on which way a 120v/15A receptacle should be placed, ground up or ground down.
A reasonable explanation was given, ground on top because it is safer than the ground on the bottom. If anything fell in contact with a plug that is partially engaged/energized and partially disengaged/exposed, that objects falling by gravity would hit the ground prong first. Evidentially the code book shows the UL-ULC/CSA diagram as a ?u? ground and not an ?n? ground.
For the horizontal position the recommended safest way to install receptacles is to have the grounded neutral conductor on top with the wide flat prong over the narrow flat prong which is connected to the live conductor. The provided explanation used the same reasoning as above; in the case of accidental contact with energized and exposed prongs.
Also, in the vertical position with the ground at the bottom, using polarized plugs, the neutral prong is positioned slightly higher than the hot prong because the neutral is wider than the hot. So it is also more probable for falling objects to come into contact with the neutral first, but can still cause a short circuit across both prongs.
The rest of the class stood by the, stay with what is common, and continue to do what was done in times past, as most installers have the ground at the bottom. The way they have always ever done or most commonly seen.
Perhaps this could be a result of one the first journeyman electricians that figured the most logical way to install them was to have receptacles look like the face of a person, with the two prongs being eyes, and the third as the nose and mouth. Or he thought the ground should point towards the ground. GROUND to GROUND?
I?m not sure and I don?t know, I can only speculate at this time. I am curious to know such history and the true story of the receptacle. If I don?t find out soon, I won?t sleep properly at night. Please help me, or I will be forced to surf the web endlessly until I find it, and my wife will end up pulling the plug. One way or another, and in more than one way, let?s share our knowledge. I have heard there is more than one way to skin a cat.
Trivia Time. Do you know?
What are the metals used for the green grounding screw, the white wire screw and the hot wire screw? Anyone with knowledge in metallurgy?
How about the materials specifications and dimensions for the most common receptacle in the world? Who makes it and how many are sold world-wide each year?
When u get into 90 degree plug heads, it could be decided which way is best depending on your cord routing, from my experience in most cases the 90 degree head should be down with cord towards the ground, leaving the ?u? ground as an ?n? ground viewing it with your head up over your shoulders and two feet on the ground.
I believe that at least in North America that the Electrical manufacturers association is standardized on this issue, but there does seem to be some controversy to ground up or ground down.
Finally, is it ?u? or ?n??
By,
Bright Idea
