Electrical question neutral and ground.

[Fiveohhh]

Just curious wondering why the ground and neutral are seperate. Is the ground just there basically as a safety line? I'm talking about a basic 110v circuit.

 

[dighn]

yes ground is for safety

 

[Demon-Xanth]

Ground should NEVER be carring current. But if something goes wrong, that's why it's there. In a GFCI circuit, if ground IS carrying current, then the hot gets disconnected.

 

[AlienCraft]

Safety only.

 

[Fiveohhh]

Thanks for the info just did some googling and found out some more info.

 

[SlushieKen]

The 'ground' is typically grounded at your house (to a water pipe often times). It's purpose is a place for the electricity to go if it manages to reach the 'case' of the device.

IE if your dishwasher was to leak into the motor housing (motor housing and dishwasher itself are both grounded) it could allow electricity to reach the housing due to water conducting the charge. The ground on the dishwasher housing would give a path of less resistance (less than you anyways) to go to so you don't smoke yourself when you touch it.

The neutral is actually grounded I beleive at your local power reduction station, where the high power lines are dropped to 220 before they feed your neighborhood grid. It may also actually be closer, like your local transformer, but I understand the point is that it is supposed to be sufficiently distanced from the house ground point such that these cannot conduct to each other.

 

[AlienCraft]

Originally posted by: SlushieKen
The 'ground' is typically grounded at your house (to a water pipe often times). It's purpose is a place for the electricity to go if it manages to reach the 'case' of the device.

IE if your dishwasher was to leak into the motor housing (motor housing and dishwasher itself are both grounded) it could allow electricity to reach the housing due to water conducting the charge. The ground on the dishwasher housing would give a path of less resistance (less than you anyways) to go to so you don't smoke yourself when you touch it.

The housing of the motor is usually attached to the chassis of the Dishwasher and that is what conducts the electricity, not the water. The leaking is typically caused by deteriorating insulation on the motor windings.

The neutral is actually grounded I beleive at your local power reduction station, where the high power lines are dropped to 220 before they feed your neighborhood grid.

Actually the lines on the power pole are at a much highger voltage than 220. It is the transformer on the pole (or in the box above ground, depending on locality) that does the reduction to 220/240vAC for home consumption. Inside your service panel is a connection that bonds Ground to Neutral.

It may also actually be closer, like your local transformer, but I understand the point is that it is supposed to be sufficiently distanced from the house ground point such that these cannot conduct to each other.

Your understanding is incorrect. The transformer housing may be grounded, but the neutral lead is not grounded at the transformer.

 

[NogginBoink]

Neutral and ground are tied together at the breaker box.

It's illegal to tie them together anywhere else.

 

[DrPizza]

Originally posted by: Demon-Xanth
Ground should NEVER be carring current. But if something goes wrong, that's why it's there. In a GFCI circuit, if ground IS carrying current, then the hot gets disconnected.

Actually, the circuit is disconnected if the current in the neutral isn't almost exactly the same as the current in the hot. It doesn't matter if the ground is carrying the current or not, the GVCI doesn't check the ground wire.
(But, if the ground wire *was* carrying a current back, of course the neutral and hot would have different currents.) I can't recall the tolerance - how many milliamps apart they could be before it trips the GFCI

 

[RossGr]

Just an interesting ground story!

While installing my back yard sprinkler system last summer I discovered that the Satilite Dish installer used a PVC CONDUIT for safety Ground of our Satilite TV system!

Yes, I moved it to a real ground!

 

[Demon-Xanth]

Dr: iirc, 40mA