in a electrical plug...which one is the ground wire?
the one with a big copper head or the small one?

neither. grounded plugs have a 3rd prong on bottom.

Actually, the small one is the ground one in a two-prong plug.

In plugs, the big one is "Hot", the little one is "Neutral", and if there's a third one, the third prong on the bottom which is cylindrical, is "Ground". Ground and Neutral actually go to the same place in an electrical circuit box (i.e. they're tired together) so they're both ground. The difference is that the Ground prong is usually tied to the device's case so that if you're working inside of it, you're less likely to electrocute yourself. Devices that don't have the Ground prong don't have that protection.

i'm confused. you said the small one is the ground and then you said it was the neutral(what i said).

Ground and Neutral are both the same thing. They're tied together. They're different types of ground. In a two-prong outlet that doesn't have a Ground prong, the Neutral acts as the ground, i.e. current flows out from the Hot one and into the Neutral one.

For example, if you have a 2-prong lamp and a 3-prong heater both plugged in, the fan's neutral prong will be at the same voltage as the heater's neutral AND the heater's ground prong.

Electrically, Neutral and Ground are the same node.

ya i just always separate them into neutral and ground in my head. no use in calling them the same thing when they serve different functions is all i'm saying.

Larger Prong is the Neutral, Smaller one is the "Hot" connection. Technically Neutral and Ground are NOT the same thing, but in typical home wiring they behave similarly "Unless" you have a parallel circuit and then they are absolutely NOT the same (Per Electrical Code they are absolutely NOT the same). If you have a parallel circuit and do not keep your Neutral and Grounds separated, it could prove dangerous and even deadly. While it is true in your main Electrical Box the Neutral and Grounds are on the Same Bus, in an auxiliary Box they MUST Remain Separate (Floating Neutral bus) until they join in the main bus so as to avoid Voltage in the Neutral on Parallel circuits. In a proper Circuit the Neutral and Ground should carry "Zero" voltage.

In your illustration, there is no Ground connection.

Remember, electricity is not a hobby, leave it to someone who knows what they are doing........


This post was edited by FullArcFG on Oct 4 2011 06:58pm

reminds me, need to revise some electricity physics