DarkBlack
Elite Member
That allows for neutral bonding, upstream of your panel, usually at your meter socket. Depending on jurisdiction , year done, and electrician , the bonding will be there or your panel, or both
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ultrarunner
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A lot of homes here date from the 1920's with no grounds or even a ground rod or bond to water pipe.
As long as it is in good as-built condition no code issues.
The problem comes when a 2 prong outlet is replaced with a 3 prong grounded outlet indicating ground where none exists...
Exception is GFCI can be installed where no ground exists.
As long as it is in good as-built condition no code issues.
The problem comes when a 2 prong outlet is replaced with a 3 prong grounded outlet indicating ground where none exists...
Exception is GFCI can be installed where no ground exists.
LittleBill21
Elite Member
that photo is not actually showing separate grounds, that's a shared neutral ground bar. a separate bus bar would be install if used as a sub panel, you can see the screw holes on the right side.
They only want one central ground to neutral point, deals with potential, they don't want current running over ground unless in safety as it reduces its safety as i "assume" the resistance is a bit higher when there is a current passing through it, that shouldn't be
MAX-24-Dean
Veteran Member
A place to purchase ground bars for electrical panel. Low priced factory original equipment.
shttps://www.simplybreakers.com/products/eaton-ground-bar-gbk14
WranglerX
Super Member
Any Lowes, Home Depot or ACE hardware should have ground bars....
grsthegreat
Super Star Member
In the panel pictured, there is a jumper connecting both of the side bars. On some brand panels you can remove this jumper and add a bonding screw to allow grounds to land on the right bar and neutrals to land on left. But what most electricians do is simply add separate ground busses to the can. In this particular panel, there are also neutral rails added for afci and gfci breakers, so you CANT remove the jumpers. There are pretapped holes for this and every brand of panel sells the buss bars.
This allows for a cleaner installation and ease of wiring.
WinterDeere
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Sub-panels can be ground-bonded, at least back when I learned NEC, and I would be surprised if that has changed. They are usually not, especially if within the same structure as the primary, but don't confuse convention with rules.
There are two ways to feed a sub-panel:
1. Bring ground + neutral from main panel, and remove the ground bonding tab in the sub-panel.
2. Bring only neutral from the main panel, and provide a new ground at the sub-panel, in which case you must ground-bond the neutral at the sub-panel.
Method 1 is generally used when staying within the same structure, method 2 becoming more common when feeding an external structure (pool house, garage, etc.), in order to save pulling a 4th conductor over longer distances.
What it comes down to is that the neutral tap on the transformer outside your house is floating, and must be tied to ground somewhere, lest any imbalance in loading the two hot legs causes the neutral voltage to drift away from ground. This all makes perfect sense when you consider the arrangement of the utility transformer, and the associated impedances, realizing that the neutral is only carrying any small difference in current between the loading of the two hots.
Put more simply, if you have 50A load on L1 and 35A load on L2, the neutral will see 15 amps of current. If the output impedance of the transformer runs around 2 ohms, then you're going to see the neutral floating up around 30 volts, without ground bonding.
As to why neutral is only grounded once at building entrance, and not duplicated at every panel, is about ensuring the neutral current on each branch circuit or feed stays on the neutral wire, and not the ground conductor. If you bonded them at every sub-panel, in case 1 above where you're running parallel conductors, then neutral current could flow on the ground conductor.
Personally, I think method 2 above is better for sub-buildings, and wouldn't be surprised at all if NEC heads (or already headed) this direction, for sub-panels in auxiliary structures. I say that because, when run over long distances, even neutral feeds can develop voltage, in proportional to the current flowing in that conductor.
There are two ways to feed a sub-panel:
1. Bring ground + neutral from main panel, and remove the ground bonding tab in the sub-panel.
2. Bring only neutral from the main panel, and provide a new ground at the sub-panel, in which case you must ground-bond the neutral at the sub-panel.
Method 1 is generally used when staying within the same structure, method 2 becoming more common when feeding an external structure (pool house, garage, etc.), in order to save pulling a 4th conductor over longer distances.
What it comes down to is that the neutral tap on the transformer outside your house is floating, and must be tied to ground somewhere, lest any imbalance in loading the two hot legs causes the neutral voltage to drift away from ground. This all makes perfect sense when you consider the arrangement of the utility transformer, and the associated impedances, realizing that the neutral is only carrying any small difference in current between the loading of the two hots.
Put more simply, if you have 50A load on L1 and 35A load on L2, the neutral will see 15 amps of current. If the output impedance of the transformer runs around 2 ohms, then you're going to see the neutral floating up around 30 volts, without ground bonding.
As to why neutral is only grounded once at building entrance, and not duplicated at every panel, is about ensuring the neutral current on each branch circuit or feed stays on the neutral wire, and not the ground conductor. If you bonded them at every sub-panel, in case 1 above where you're running parallel conductors, then neutral current could flow on the ground conductor.
Personally, I think method 2 above is better for sub-buildings, and wouldn't be surprised at all if NEC heads (or already headed) this direction, for sub-panels in auxiliary structures. I say that because, when run over long distances, even neutral feeds can develop voltage, in proportional to the current flowing in that conductor.
DarkBlack
Elite Member
I should have zoomed on the photo. That’s a PON panel. I’ve never played with PON breakers before. I think you can still use certain standard breakers with it too.
grsthegreat
Super Star Member
The option not to run a subpanel without also running a ground wire went away some time ago. Now you HAVE 2 run 4 wire subpanels, even within the same structure. I dont recall what nec revision this occured.
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Because the neutral at the sub-panel may not be at ground potential.
This would be true if the load on the two phases in the sub-panel is not equal, so there is some current flowing in the neutral. With current flowing, and some small resistance in the neutral conductor, there is a voltage difference between the neutral buss in the sub-panel and the one in the main panel. Probably small, but some.
You want the ground busses in all panels to be a ground potential.