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Author Topic: Grounded and Grounding.  (Read 8135 times)

Phil Graham

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Re: Grounded and Grounding.
« Reply #10 on: November 20, 2013, 12:57:01 pm »

Please dont kill me for asking.

My understanding so far, Grounded is the Neutral. The grounding cable (green) is a dedicated backup cable also connected to the Neutral at the service entry, in case of the equipment chassis going live, this cable will carry voltage/current back to the neutral.

So where and why, is the actual earth connection (a rod going into the soil) ?

This is with regard to single phase systems only.

Sidhu,

You've got the concepts correct, which is more important than the terminology. But we could chat about the official definitions more if you are interested. I know you are in India, so our US nomenclature might not be of much practical use to you. The following definitions are quoted from the 2013 draft of the proposed 2014 NEC as a couple points of interest:

Quote
Neutral Conductor. The conductor connected to the neutral point of a system that is intended to carry current under normal conditions.

Neutral Point. The common point on a wye-connection in a polyphase system or midpoint on a single-phase, 3-wire system, or midpoint of a single-phase portion of a 3-phase delta system, or a midpoint of a 3-wire, direct-current system.
Informational Note: At the neutral point of the system, the vectorial sum of the nominal voltages from all other phases within the system that utilize the neutral, with respect to the neutral point, is zero potential.

Because the neutral and the green wire (EGC in NEC terms) are physically connected to the earth (GEC + grounding electrode in the NEC) by the bonding of all three systems (neutral + EGC +GEC) for the typical single phase system, both the green wire and the neutral are grounded (physically linked to earth) in this case.

As you correctly assert, the current returns to the panel via the neutral point. This neutral point in the panel is typically then connected to a center "tap" on a transformer's secondary at the supply. This center tap is physically linked to the high voltage point by the secondary winding, completing the current path of the circuit.

In the case of a fault, the green (EGC) carries the current back to the neutral/green/ground rod bonding point. Here, a current divider is formed between the neutral and the ground rod. Because the secondary winding of the supply is very low impedance, the vast majority of the current returns via this path.

If there happens to be a current path between the grounding rod of the panel, and the grounding point of the supply center tap, then a current can flow back to the supply by this other, typically high impedance, path. Sometimes this panel -> ground -> ground -> supply center tap path exists, and sometimes it doesn't.

A ground rod's purpose for our pro audio purposes is to hold the green and neutral wires near the local voltage potential of the planet. A secondary purpose is to provide an anchor voltage point. A ground rod also has limited capacity to store electrical energy electrochemically in the soil.

Hopefully this is helpful to you.
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Nitin Sidhu

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Re: Grounded and Grounding.
« Reply #11 on: November 23, 2013, 02:29:21 pm »

Hello Phil!

Getting the concept right is what im studying towards. Terminology is cause I am currently educating myself on primarily American forums, and reading American literature. My understand of the bonding, and other elementary electrical concepts, come from a recommendation on this forum, Wiring Simplified, 43rd Edition. 2011 NEC code.

While it may not apply to India, I am not aware of any code by the Bureau of Indian Standards that is easily accessible. Even though I am sure there is, and it is probably a copy of the British code from the 50's or something.

My goal here is not to follow code, but to follow safe Practices. Which I am sure are constant. Most of you here would be harrowed by how callously we take electricity around these parts.

Ill be reading you post over and again, it is a bit of jargon for me yet, and revert with any further queries. I can only thank you all for helping me understand AC better.

Regards,
Sidhu

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Lyle Williams

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Re: Grounded and Grounding.
« Reply #12 on: November 24, 2013, 03:53:27 am »

Quote from: Nitin Sidhu
My goal here is not to follow code, but to follow safe Practices. Which I am sure are constant.

The code does attempt to capture safe practices.  The problem with following "safe practices" rather than the code is that an individual's electrical knowledge is probably centred around the idea that everyone else's work has been done properly and that nothing breaks or goes wrong.  Electrical codes capture the real world faults and errors that occur.
« Last Edit: November 24, 2013, 04:24:54 am by Lyle Williams »
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John Roberts {JR}

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Re: Grounded and Grounding.
« Reply #13 on: November 24, 2013, 10:43:58 am »

The code does attempt to capture safe practices.  The problem with following "safe practices" rather than the code is that an individual's electrical knowledge is probably centred around the idea that everyone else's work has been done properly and that nothing breaks or goes wrong.  Electrical codes capture the real world faults and errors that occur.
While it has been my experience that code here is safe practice, I would not make ASSumptions that code always is in other cultures. One would ASSume that the British left behind some discipline in such regulatory matters. I would expect more variability in the execution and enforcement.

At the same time I would advise caution before ASSuming that code is not safe practice unless you understand how and why that questionable code came to be. Even if you do not understand the why behind some code, unless you see that it is creating some obvious hazard, try to follow it.

JR
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Jonathan Johnson

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Re: Grounded and Grounding.
« Reply #14 on: November 24, 2013, 08:43:17 pm »

While it may not apply to India, I am not aware of any code by the Bureau of Indian Standards that is easily accessible. Even though I am sure there is, and it is probably a copy of the British code from the 50's or something.

It appears that there is such a code. I found this:

IS SP 30: National Electrical Code (2011); Bureau of Indian Standards
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Nitin Sidhu

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Re: Grounded and Grounding.
« Reply #15 on: November 24, 2013, 09:38:16 pm »

It appears that there is such a code. I found this:

IS SP 30: National Electrical Code (2011); Bureau of Indian Standards

haha! Than you Jonathan! As embarrassing as you finding it and not me is!

Regards,
Sidhu
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ProSoundWeb Community

Re: Grounded and Grounding.
« Reply #15 on: November 24, 2013, 09:38:16 pm »


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