How to check if panel grounded?

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Old 11-04-18, 09:35 PM
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How to check if panel grounded?

I know that if I use a multimeter to check a receptacle between hot and ground I can check if it's grounded but does this just mean grounded to the panel or is it grounded all the way to earth?
I've seen 3 panels I'm checking,
one I can find the ground wire in the crawl space but it's connected to the neutral bar in the panel,
One seems to have a cut ground wire in crawl space but could be old since receptacles are showing grounding,
The third I cannot find the ground wire in crawl space but receptacles are measuring grounded.
 
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Old 11-05-18, 12:44 AM
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Receptacle grounding is via a wire or other path such as conduit
back to the panel (EGC) and can be good even if the panel isn't grounded to earth.

but it's connected to the neutral bar in the panel,
Connection to the "neutral" bar would be correct of of it is the first panel with a fuse or breaker. Ground and neutral are combined at the first panel.

The third I cannot find the ground wire in crawl space but receptacles are measuring grounded
If it is fed by a panel with a GEC (earth ground) and is in the same structure no GEC is required.

EGC is a low resistance path for clearing shorts to a metal equipment housing and is the ground slot on a receptacle.

GEC is a wire from the panel to earth to help balance atmospheric charges. It can not be used as an EGC.
 

Last edited by ray2047; 11-05-18 at 05:09 AM.
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Old 11-05-18, 05:02 AM
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How do I check if the panel is grounded properly to an earth rod or metal pipe?
 
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Old 11-05-18, 05:29 AM
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"How do I check if the panel is grounded properly to an earth rod or metal pipe? "

Visual inspection.

Dada dada #4 copper connected to the cold water pipe within 5 feet of where it exits the house undeground dada dada ...

The "first" panel in any given building is connected to the grounding electrode system.
 
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Old 11-05-18, 06:46 AM
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I cannot find the grounding locations for 2 of the panels. With a meter, is there a way to check the panel is grounded?
the panels are right next to the main service meter - could the grounding be in the service meter?
 
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Old 11-05-18, 07:48 AM
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Are they on seperate buildings? As repeatedly stated if in the same building only the first should have a ground rod (GEC). the other two only an EGC from the first.panel.
 
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Old 11-05-18, 09:09 AM
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Same building but 3 separate panels with 3 separate meters and service points.
Would they all use the same ground wire?

Is there no other way to check for grounding than by viewing? What if the wire is broken somewhere - how would you know?
 

Last edited by qwertyjjj; 11-05-18 at 10:56 AM.
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Old 11-06-18, 02:13 PM
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Can't be done with a meter?
 
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Old 11-07-18, 10:38 AM
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Can't be done with a meter?
No, not without disconnecting everything.

There are often multiple paths to ground which your meter won't differentiate. A garbage disposal connected to metal piping might be a path. Or your furnace connected to a gas pipe - which may be bonded out at the street somewhere. Or a metal sheathed cable (AC/MC) touching a plumbing pipe.

NEC has specific bonding/grounding methods to make it easy to visually inspect your grounding methods. Unfortunately there's no good way to test an earth ground in a fully-connected electrical system.

(There are tools to test a specific earth ground - as in how effective a ground rod is, but that's much more specialized and doesn't seem to be your question.)
 
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Old 11-07-18, 01:22 PM
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Same building but 3 separate panels with 3 separate meters and service points.
BHut is it a single drop from the pole?
 
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Old 11-07-18, 07:20 PM
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There's 3 conduits entering the building from the electric pole. 1 service entrance from the front to ground then the 2nd and 3rd floors have their service from a different pole at the back of the house.
 
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Old 11-07-18, 10:31 PM
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Suggest you call an electrician out to evaluate the situation. Multi family installations should be evaluated by a pro.
 
 

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