EGC carrying current

[zcanyonboltz]

I'm an RW in an apprenticeship program learning to be an inside wireman. Any way... when does the EGC between two panels carry current? When operating normal or when there is a ground fault or short circuit or all the time?
Thanks

 

[jumper]

I'm an RW in an apprenticeship program learning to be an inside wireman. Any way... when does the EGC between two panels carry current? When operating normal or when there is a ground fault or short circuit or all the time?
Thanks

An EGC is supposed to only carry current under ground fault conditions.

 

[zcanyonboltz]

An EGC is supposed to only carry current under ground fault conditions.

Thanks, so then the grounding conductor only carries current under ground fault conditions as well.

 

[zcanyonboltz]

So the grounded conductor between two panels only carries current during normal operation, and not when there is a short circuit or ground fault? And a bit further the grounded conductor between the MBO and source of power can carry current during normal operation as well.

 

[user 100]

So the grounded conductor between two panels only carries current during normal operation, and not when there is a short circuit or ground fault? And a bit further the grounded conductor between the MBO and source of power can carry current during normal operation as well.

Yes, the grounded (neutral) conductor normally carries current-the egc doesn't and isn't supposed to during normal operation.

 

[jumper]

Lemme see if I can explain this coherently as I understand it.

Ground fault = Line/hot - EGC/grounding fault, EGC does not carry current during normal operation.

Short circuit = Line - Line or Line - Neutral/grounded fault

In general the neutral carries the imbalance of current between lines/hots/phases during normal operation, but will also carry current in a L-N fault.

I am not very good at explaining stuff, so I hope this some sense to you.

 

[ActionDave]

I am not very good at explaining stuff, so I hope this some sense to you.

That was pretty good.

 

[Carultch]

I'm an RW in an apprenticeship program learning to be an inside wireman. Any way... when does the EGC between two panels carry current? When operating normal or when there is a ground fault or short circuit or all the time?
Thanks

An EGC (green wire) should never carry current, except under fault conditions.
The ground-voltage conductor that should be carrying the normal operational return current, is the grounded conductor (aka neutral, the white or gray wire).

If you are counting current-carrying conductors for ampacity purposes, the EGC never counts. The neutral might or might not count, and there are specific reasons why it would. In general, neutral counts if it is a mandatory part of the return path of the current, or if significant harmonic loads accumulate onto it, causing it to generate heat.

In order to make sure that the EGC doesn't carry current, it should only be bonded to neutral at exclusively one location: at the main service disconnect.

 

[kwired]

Thanks, so then the grounding conductor only carries current under ground fault conditions as well.

You need to get terminology straight here. EGC and "grounding" conductor are the same thing, but equipment grounding conductor (EGC) is the more technically correct name for it.

Grounded conductor is a conductor that may or may not carry current during normal operations. Most of the time is also the neutral conductor of the system, but not always. Corner grounded delta systems have a grounded conductor but it is not a neutral conductor. Two wire systems - maybe a separately derived 120 volt control circuit, will have one conductor grounded, but technically that conductor is not a neutral though many will call it that.

 

[ATSman]

A matter of degree

A matter of degree

This is what I remember but someone can correct me if I am in error. Under normal conditions the EGC should not be carrying enough current to trip GFR devices to protect equipment. These devices should be set above this normal threshold. Because there is no such thing as a perfect insulator (including age of equipment, dirt, moisture, etc) the ERC will carry some current jn the real world. If my memory serves me the Westinghouse rule of thumb is the leakage current (measured in the neutral to ground strap) should be in the range of around 1% of the total load current (10 amps for a 1000A load.) With higher currents the wiring should investigated.

 

[zcanyonboltz]

You need to get terminology straight here. EGC and "grounding" conductor are the same thing, but equipment grounding conductor (EGC) is the more technically correct name for it.

Grounded conductor is a conductor that may or may not carry current during normal operations. Most of the time is also the neutral conductor of the system, but not always. Corner grounded delta systems have a grounded conductor but it is not a neutral conductor. Two wire systems - maybe a separately derived 120 volt control circuit, will have one conductor grounded, but technically that conductor is not a neutral though many will call it that.

Yea I always thought the EGC as the ufer,water pipe or ground rod ground and the grounding conductor was the ground in the actual branch circuit or feeder.
I do know from reading code for my RW license exam that the neutral is the grounded conductor and grounding conductor is the ground... so what you're saying is the ECG is the ground rod or ufer, water pipe etc. and the actual branch circuit or feeder ground that they're the same thing. For the vocab I'm getting used to code and school talk being bit different from job site talk.

Thanks everyone for the replies they make sense.

 

[jtinge]

Remember older dimmer switches that used the EGC to operate will be a source of neutral current on the EGC.


Sent from my iPhone using Tapatalk

 

[mbrooke]

ATSman I wonder the same. In any system a very small amount of current (relative to the phase and neutral conductors) is always present from capacitive coupling to anything bonded (grounded). Some equipment also naturally leaks like surge suppressors and VFDs if I am correct. When applying ground fault protection the GFP must take that into account.


However, outside of that no direct connections of neutral to ground can exist beyond the main bonding jumper.

 

[mbrooke]

Yea I always thought the EGC as the ufer,water pipe or ground rod ground and the grounding conductor was the ground in the actual branch circuit or feeder.
I do know from reading code for my RW license exam that the neutral is the grounded conductor and grounding conductor is the ground... so what you're saying is the ECG is the ground rod or ufer, water pipe etc. and the actual branch circuit or feeder ground that they're the same thing. For the vocab I'm getting used to code and school talk being bit different from job site talk.

Thanks everyone for the replies they make sense.

Wires running to say a ground rod or UFER are called "grounding electrode conductors" or GEC.

 

[kwired]

Yea I always thought the EGC as the ufer,water pipe or ground rod ground and the grounding conductor was the ground in the actual branch circuit or feeder.
I do know from reading code for my RW license exam that the neutral is the grounded conductor and grounding conductor is the ground... so what you're saying is the ECG is the ground rod or ufer, water pipe etc. and the actual branch circuit or feeder ground that they're the same thing. For the vocab I'm getting used to code and school talk being bit different from job site talk.

Thanks everyone for the replies they make sense.

EGC = equipment grounding conductor

GEC = grounding electrode conductor

they are not the same thing.

they both are supposed to be at ground potential

the GEC may have some current on it during normal operation - this will cause voltage drop and a voltage above ground potential in some situations.

They both get connected to the grounded conductor at the service, first disconnecting means or source of a separately derived system.

Any voltage drop on the grounded conductor at that point can easily raise the voltage to ground on the rest of the equipment grounding conductor network, and is not an abnormal condition - but still can cause problems.

 

[zcanyonboltz]

EGC = equipment grounding conductor

GEC = grounding electrode conductor

they are not the same thing.

they both are supposed to be at ground potential

the GEC may have some current on it during normal operation - this will cause voltage drop and a voltage above ground potential in some situations.

They both get connected to the grounded conductor at the service, first disconnecting means or source of a separately derived system.

Any voltage drop on the grounded conductor at that point can easily raise the voltage to ground on the rest of the equipment grounding conductor network, and is not an abnormal condition - but still can cause problems.

EGC GEC
Thanks, those are terms I was thinking as the same thing, I was not thinking of GEC .