4 ms·
" There's 3 prongs arranged in a triangle, each of equal length" No, the earth pin is noticeably longer. This serves two purposes - first, to ground the device
by sc00ter 14y ago
" There's 3 prongs arranged in a triangle, each of equal length"
No, the earth pin is noticeably longer. This serves two purposes - first, to ground the device being plugged in before it is live; second, to retract the mechanical barriers that are ordinarily across the entrance to the power pins, in order that the plug can be inserted, but stray fingers, paperclips, keys, or other conductive items cannot (without some effort and intent).
As an aside - as a result of the mechanical barrier across the power pins, the plastic socket safety inserts that parenting stores sell are completely redundant, and arguably a scam.
- TazeTSchnitzel 14y agoOh, I notice the Earth pin is longer now that you mention it, you're right. Makes sense, considering it retracts the flaps.
- brudgers 14y agoIt's simultaneous pressure on the two live prongs which allows the plug to enter the receptacle - a two pronged plug still works. See: http://www.nfpa.org/itemDetail.asp?categoryID=1508&itemID=36117&URL=Safety%20Information/For%20consumers/Causes/Electrical/Tamper-resistant%20electrical%20receptacles&cookie_test=1 http://www.nfpa.org/itemDetail.asp?categoryID=1508&itemI...
- quarterto 14y agoWe're talking about UK plugs here. It's impossible to insert a plug without the ground pin entering first. I've had a few double-insulated AC adaptor where the dummy plastic ground pin has broken off (in the socket!) rendering the plug unusable in most sockets.
- brudgers 14y agoMost receptacles [in the US] do not have flaps or any other mechanical part. If they had the sort of contraption described, ungrounded plugs would not work and there would be a significant risk due to failure. The ground pin is longer because it is far safer to ground first before running current, and to continue to ground after disconnecting the current.
- ars 14y agoNot anymore. All new receptacles in the US have a protection that will not allow you to insert anything into just one side. You have to insert prongs into both sides of the outlet at the same time in order for it to release. http://en.wikipedia.org/wiki/NEMA_5-15#Tamper-resistant_receptacles http://en.wikipedia.org/wiki/NEMA_5-15#Tamper-resistant_rece...
- marshray 14y agoI've never seen one of these things, not even at Home Depot.
- ars 14y agoLook again - I had a hard time finding anything else last time I went. They are labeled with "TR". (There is also WR for water resistant, and of course TR and WR together, sigh. Prices are going up since now stores need to stock 4 times as many types.)
- btgeekboy 14y agoThey exist, but they sell them alongside the normal ones at an additional cost.
- icarus_drowning 14y agoI live in an older home (1955), but when we bought it in 2010 we had the original owner do electric work that had failed inspection-- as a result (and due to the local laws here), this is the only kind of socket we have.
- 14y ago