Bonding EGC and neutral at load-centers

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mobo

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MO USA
OK, let's say you come off your main panel in your house to feed a load-center out in your shed. The load-center will be 120 volts, so of course will only accommodate single-pole breakers. Let's say I run 2C/with grd UF cable to this loadcenter. The load-center only has one ground-bar in it. So, of course I wire the black wire from this UF cable to the hot lug in the load-center, but in light of not bonding the neutral(grounded conductor) and the EGC in sub-panels, what do I do with the white wire (neutral) and the bare wire (EGC), what with there only being one ground-bar in this load-center?
 
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don_resqcapt19

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You have to add an equipment grounding bar. If the supply is a feeder and not just a branch circuit, you will also have to add grounding electrodes at the second building.
 

Smart $

Esteemed Member
Location
Ohio
If there is no neutral bar (isolated from the enclosure) in the panel then it is likely only rated for use as service equipment. You cannot use it as a subpanel unless there are listed modifications to make it into a non-service panel.
 

mobo

Member
Location
MO USA
If there is no neutral bar (isolated from the enclosure) in the panel then it is likely only rated for use as service equipment. You cannot use it as a subpanel unless there are listed modifications to make it into a non-service panel.



Let's say it is a neutral bar and isolated from the enclosure....do you land both the white wire and bare wire on this neutral bar? As well as the white wires and bare/green grounding wire from the branch circuits exiting the load-center?
 

Smart $

Esteemed Member
Location
Ohio
Let's say it is a neutral bar and isolated from the enclosure....do you land both the white wire and bare wire on this neutral bar? As well as the white wires and bare/green grounding wire from the branch circuits exiting the load-center?
If it is a neutral bar (isolated from enclosure), then you need to do as Don said... add an equipment grounding bar. Neutrals to neutral bar. EGC'c to EGC bar.
 

mobo

Member
Location
MO USA
If it is a neutral bar (isolated from enclosure), then you need to do as Don said... add an equipment grounding bar. Neutrals to neutral bar. EGC'c to EGC bar.

Thanks!

One more question.... what if there is no EGC in the cable/wires feeding the load-center, just a hot wire and neutral? What do you do with the branch ckt. EGCs?
 

GoldDigger

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Thanks!

One more question.... what if there is no EGC in the cable/wires feeding the load-center, just a hot wire and neutral? What do you do with the branch ckt. EGCs?

You pull an EGC, since the configuration you hypothesize is not permitted under any current code versions.
 

infinity

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New Jersey
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OK, let's say you come off your main panel in your house to feed a load-center out in your shed. The load-center will be 120 volts, so of course will only accommodate single-pole breakers. Let's say I run 2C/with grd UF cable to this loadcenter. The load-center only has one ground-bar in it. So, of course I wire the black wire from this UF cable to the hot lug in the load-center, but in light of not bonding the neutral(grounded conductor) and the EGC in sub-panels, what do I do with the white wire (neutral) and the bare wire (EGC), what with there only being one ground-bar in this load-center?

mobo is this all hypothetical? Why would someone want to install a subpanel is this fashion?
 

GoldDigger

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mobo is this all hypothetical? Why would someone want to install a subpanel is this fashion?

And, getting directly to the point, if you bring one hot, one neutral and one EGC to a panel that feeds line to neutral loads (duh), you must have separate bars in the panel. The neutral and the EGC are both required and cannot be bonded to each other.

If instead you bring two hots and an EGC (from a 120/240 source) and feed only line to line loads, you do not need a place to land the neutral since you do not need the neutral in the first place.
 

mobo

Member
Location
MO USA
mobo is this all hypothetical? Why would someone want to install a subpanel is this fashion?

I actually came across this.

They ran two hots and the neutral to the loadcenter to feed it. They ran a #6 grd to a grd rod from the loadcenter and landed that grd to the one neutral bar in the loadcenter. And the 4 ckts that they ran out of the loadcenter they landed all the white wires and EGC wires to the lone neutral bar. There are no other bars in the loadcenter.
 

GoldDigger

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I actually came across this.

They ran two hots and the neutral to the loadcenter to feed it. They ran a #6 grd to a grd rod from the loadcenter and landed that grd to the one neutral bar in the loadcenter. And the 4 ckts that they ran out of the loadcenter they landed all the white wires and EGC wires to the lone neutral bar. There are no other bars in the loadcenter.
Not compliant with current codes if the panel is a sub panel rather than a service panel. Not tremendously unsafe, but not the best and not allowed currently.
 

Smart $

Esteemed Member
Location
Ohio
Not compliant with current codes if the panel is a sub panel rather than a service panel. Not tremendously unsafe, but not the best and not allowed currently.
It used to be compliant for a subpanel in a separate building or structure. I believe it was prior to 2005 and Code still has an exception for existing installations.
 

GoldDigger

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Thanks for your replies.

What exactly do you mean by service panel?
A service panel is where the service conductors from POCO first encounter a disconnect and overcurrent protection.
The NEC rules on service conductors are quite strict since the fire and other damage risks are much higher since POCO does not effectively protect the circuit from faults.
Often before overcurrent protection at the transformer kicks in the wires (or their terminations) melt.
But at the same time POCO does not run an EGC separate from their neutral. The neutral is grounded at the transformer secondary (not NEC) and at the customer end (NEC).

Sent from my XT1585 using Tapatalk
 

ActionDave

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Durango, CO, 10 h 20 min from the winged horses.
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I actually came across this.

They ran two hots and the neutral to the loadcenter to feed it. They ran a #6 grd to a grd rod from the loadcenter and landed that grd to the one neutral bar in the loadcenter. And the 4 ckts that they ran out of the loadcenter they landed all the white wires and EGC wires to the lone neutral bar. There are no other bars in the loadcenter.

If it was wired before 2005 was adopted and there are no other metallic paths connecting the two buildings then it's a legal install and not unsafe.
 

mobo

Member
Location
MO USA
If it was wired before 2005 was adopted and there are no other metallic paths connecting the two buildings then it's a legal install and not unsafe.

So if they changed the code on it in 2005 i have to ask..... was it because it "was" considered unsafe? But they now just want all new installations/upgrades done under the 2005 restrictions?
 

winnie

Senior Member
Location
Springfield, MA, USA
Occupation
Electric motor research
The goal of the electrical code is 'practical safeguarding', not _perfect_ safety.

As the code evolves, what is considered 'practical' changes.

First equipment changes, which makes some forms of safety much cheaper (consider GFCI devices).

Second our understanding of risks changes (unintended current flow on non-electrical metallic components such as water pipes).

Third the economy changes (while copper wire is expensive, human labor is relatively much more expensive these days).

Finally there is a significant amount of politics involved, with people (manufacturers??) working to convince the code panel that the latest and greatest hardware really is practical and should be mandated.

Taken together, this means that something considered 'safe enough' under some old version of the code is generally permitted to remain until changed. Sometimes 'grandfathering' is not permitted, if the old allowed approach really presents an immediate hazard under our current understanding.

The use of the neutral current carrying conductor as the equipment grounding/bonding conductor is a very common example of something that is not considered 'safe enough' for a new installation, but which was permitted in the past and is permitted to remain if it had been installed properly.

-Jon
 

ActionDave

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So if they changed the code on it in 2005 i have to ask..... was it because it "was" considered unsafe? But they now just want all new installations/upgrades done under the 2005 restrictions?
There is an exception in the code, 250.32 Exception no. 1, that permits existing installations to remain unaltered.

There was no justification for the change based on safety. I suppose the reason for the change was to get rid of exceptions where the grounded conductor was allowed to do double duty as the equipment grounding conductor.
 
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