Pls explain hot, neutral, and ground in layman's terms

[avash]

Originally posted by: iamwiz82
Neutral completes the circuit. Think of them as one way streets. Hot is going out from the circuit breaker, and the neutral is the return. A ground is seperate from the system, and, obviously, grounds it. A neutral can be a ground, a ground can never be neutral

+1, best response for layman's terms.

 

[AlienCraft]

Originally posted by: spidey07

Originally posted by: AlienCraft

Originally posted by: Special K
When current flows through the ground wire, is it literally being diverted to the ground? Do buildings use their own frame and the surrounding earth as a conductor?

Yes, rebar embedded in the foundation is also used as a grounding element.

And in sensitive communications systems there is a common ground to with all communication cabling and active equipment is attached. Data centers have a real problem with grounding if you don't follow specs. You wouldn't believe how many problems are caused by improber grounding in data centers. It can reak havoc.

Data and Audio (which is now just data in most instances ) both have sensitivities to grounding anomalies that are very noticeable and can be mission critical.

The building which housed the offices of BAM magazine in San Rafael subdivided and rented to some friends of mine who ran a rehearsal studio. The "buzz" from all those computers during business hours ruined their plans to just move in and start recording and webcasting. It took a Furman Balanced Power rig that I had built to quiet the ground noise.

It's called CMR = common mode rejection.

 

[futuristicmonkey]

Originally posted by: JEDI

Originally posted by: futuristicmonkey
Neutral wire is only a method to divide the 240 volt service from your local transformer into two 120v lines. Some circuits may have only hot wires..google search '3 phase delta'. A ground wire is used as a low-impedance path for fault current; it serves two purposes. One, if the metal case of a refridgerator comes into contact with a live wire, the current will pass through the ground wire back to the source of electricity....not through you, if you were to touch the fridge and were grounded. Second, because it is (normally -- only talking residential stuff here) low impedance (resistance) it will allow enough current to flow to trip the circuit's breaker. The ground wire should never be used as a current-carrying wire. Never.

so if i'm standing in a puddle of water and touch a 'live' fridge, nothing would happen because the fridge is grounded? or would something happen, and the breaker trips, thus saving my ass?

if so, how does the ground trip the breaker?

Despite the more serious answers...you'd better hope to hell the resistance of the ground wire is much less than that of you+the puddle

 

[spidey07]

Originally posted by: AlienCraft
It's called CMR = common mode rejection.

All to familiar with it. Seen grounding problems cripple the largest of data communication systems.

You oughta see the busbars and mesh grounds in a "built correctly" data center.

By busbar, I really mean a hunk of copper the size of a bus.

 

[AlienCraft]

Originally posted by: spidey07

Originally posted by: AlienCraft
It's called CMR = common mode rejection.

All to familiar with it. Seen grounding problems cripple the largest of data communication systems.

You oughta see the busbars and mesh grounds in a "built correctly" data center.

By busbar, I really mean a hunk of copper the size of a bus.

mmmmmmmmm copper </homer simpson>

 

[spidey07]

Originally posted by: AlienCraft
mmmmmmmmm copper </homer simpson>

I've got plenty of stories. We should start a thread about "what NOT to do in a data center". First point being "so you decided to not ground that rack/equipment eh? And you're wondering why you're having weird problems? hmmmm. Did we decide the manual wasn't worth reading? codes/standards aren't meant to be followed? hmmm, you go cowboy"

 

[bobsmith1492]

Heh, we had a piece of test equipment at work that, when you turned on the main power, killed all AM radio signals in all five buildings. It diminished slightly after tying the chassis to nearby water pies and dropping an 8' ground rod next to it, but never went away...

On a side note, it seems no one understands what "ground" means, electrically. I can't stand it when someone says "Well I can't be shocked; I'm grounded." ??!?

 

[LordMorpheus]

Hot alternates between +120 V and -120 V for home outlets, at 60 cycles per second. Neutral is the wire that is the zero for this measurement. These wires give you the standard home AC circuit that all your ****** runs on.

Ground is a wire that runs out of your house and into, aptly enough, the ground. This is usually connected to the metal case of your DVD player and so forth as a protection, so if something goes bad and you get stuff arcing to the case it runs out of the house and into the ground instead of through your cat, Mittens. Sometimes this will trigger a fault detection circuit that will shut the outlet down (I think its in most building codes that any outlet near a sink/bathtub has this kind of fault protection) if this happens.

 

[Special K]

Originally posted by: LordMorpheus
Hot alternates between +120 V and -120 V for home outlets, at 60 cycles per second. Neutral is the wire that is the zero for this measurement. These wires give you the standard home AC circuit that all your ****** runs on.

Ground is a wire that runs out of your house and into, aptly enough, the ground. This is usually connected to the metal case of your DVD player and so forth as a protection, so if something goes bad and you get stuff arcing to the case it runs out of the house and into the ground instead of through your cat, Mittens. Sometimes this will trigger a fault detection circuit that will shut the outlet down (I think its in most building codes that any outlet near a sink/bathtub has this kind of fault protection) if this happens.

Actually it alternates between +170 V and -170 V. 120 V is the RMS measurement, which is equal to Vpeak/sqrt(2).