Insulating equipment grounding conductors

david

Senior Member
Location
Pennsylvania
551.80 Underground Service, Feeder, Branch-Circuit, and Recreational Vehicle Site Feeder-Circuit Conductors.
(A) General. All direct-burial conductors, including the equipment grounding conductor if of aluminum, shall be insulated and identified for the use.

There are several examples with- in the NEC where the equipment grounding conductor is required to be Insulated.

Here is one I found to be peculiar , I say that because it doesn’t fit the explanation I give when I am asked why the equipment ground has to be insulated. Or why can’t I use UF cable, NM cable or SER cable.

I know what my explanation is for why the insulation of the equipment ground conductor what’s yours ?
 

jap

Senior Member
551.80 Underground Service, Feeder, Branch-Circuit, and Recreational Vehicle Site Feeder-Circuit Conductors.
(A) General. All direct-burial conductors, including the equipment grounding conductor if of aluminum, shall be insulated and identified for the use.

There are several examples with- in the NEC where the equipment grounding conductor is required to be Insulated.

Here is one I found to be peculiar , I say that because it doesn’t fit the explanation I give when I am asked why the equipment ground has to be insulated. Or why can’t I use UF cable, NM cable or SER cable.

I know what my explanation is for why the insulation of the equipment ground conductor what’s yours ?
Don't generally get asked why but if I did I'd just tell em, because it says so in the code book.

JAP>
 

david

Senior Member
Location
Pennsylvania
When I started doing electrical inspections in 1990 I was at a mobile home park it was raining and I touched the metal siding of a mobile home and received a shock.

Later discussing the incident with the electrical inspector who was involved with the hiring of me, he said you could get shocked from touching a mobile home with the meter pulled, I looked a little confused and he said that’s one of the reasons they require an insulated equipment ground for the direct buried cable that supplies the mobile home.

Never forgot what he said, took me awhile to begin to understand why he said it.
 

david

Senior Member
Location
Pennsylvania
Don't generally get asked why but if I did I'd just tell em, because it says so in the code book.

JAP>
Yes that is technically correct, that it is because i understand the code to say so. And that is my Job to make that determination. However the installer / electrician is subjected to many different authorities and if he has a better understanding of why he/ she is being required to do something he is likely to remember to do it that way on other installations he is involved with or other times when inspections are not being required
 

Carultch

Senior Member
Location
Massachusetts
551.80 Underground Service, Feeder, Branch-Circuit, and Recreational Vehicle Site Feeder-Circuit Conductors.
(A) General. All direct-burial conductors, including the equipment grounding conductor if of aluminum, shall be insulated and identified for the use.

There are several examples with- in the NEC where the equipment grounding conductor is required to be Insulated.

Here is one I found to be peculiar , I say that because it doesn’t fit the explanation I give when I am asked why the equipment ground has to be insulated. Or why can’t I use UF cable, NM cable or SER cable.

I know what my explanation is for why the insulation of the equipment ground conductor what’s yours ?

You cannot use SER or NM cable underground, whether or not there is a conduit present. NM cable is off limits for all wet locations, and SER/SEU, while acceptable for wet locations, are not permitted underground with or without a raceway as indicated in the NEC uses not permitted section. UF should be precisely what you can use, as it stands for Underground Feeder cable.
 

Smart $

Esteemed Member
Location
Ohio
Note highlighted: "All direct-burial conductors, including the equipment grounding conductor if of aluminum, shall be insulated and identified for the use."

Required of an aluminum EGC solely for corrosion protection. If a direct buried aluminum EGC is not protected from corrosion, it will disintegrate in a relatively short matter of time after being buried... compared to copper. Has nothing to do with the insulative properties of the insulation. Properties for a cable to be rated direct-burial only have to do with the jacket and conductor insulation properties to protect conductors from the corrosive environment of being directly in contact with earth, especially damp earth.
 

jap

Senior Member
Yes that is technically correct, that it is because i understand the code to say so. And that is my Job to make that determination. However the installer / electrician is subjected to many different authorities and if he has a better understanding of why he/ she is being required to do something he is likely to remember to do it that way on other installations he is involved with or other times when inspections are not being required
So what's your answer as to why we are required to do so?


JAP>
 

jap

Senior Member
Note highlighted: "All direct-burial conductors, including the equipment grounding conductor if of aluminum, shall be insulated and identified for the use."

Required of an aluminum EGC solely for corrosion protection. If a direct buried aluminum EGC is not protected from corrosion, it will disintegrate in a relatively short matter of time after being buried... compared to copper. Has nothing to do with the insulative properties of the insulation. Properties for a cable to be rated direct-burial only have to do with the jacket and conductor insulation properties to protect conductors from the corrosive environment of being directly in contact with earth, especially damp earth.
:thumbsup:
 

david

Senior Member
Location
Pennsylvania
So what's your answer as to why we are required to do so?


JAP>
The example I started with was insulating alum conductors in direct buried applications, that would be one example to protect the alum from the effects the soil would have on the alum conductors itself.

But I was really thinking of the other several examples of when an equipment ground conductor are required to be insulated.

One example would be a feeder from a central distribution to a agriculture building

547.9 Electrical Supply to Building(s) or Structure(s) from a Distribution Point. (D) Direct-Buried Equipment Grounding Conductors. Where livestock is housed, any portion of a direct-buried equipment grounding conductor run to the building or structure shall be insulated or covered copper.

In this example you could use UF cable because the copper equipment ground is allowed to be covered as opposed to being required to be insulated.

In this example seems to exclude alum equipment grounding even if it was insulated

Other examples would be equipment grounding in portions of article 680 along with

552.43 Power Supply.
a continuous green color or a continuous green color with one or more yellow stripes for use as the
552.43 Power Supply.power-supply cord
be identified by a continuous green color or a continuous green color with one or more yellow stripes.
(1) insulated, color-coded feeder conductors, one of which shall be an equipment grounding con four insulated, color-coded conductors
555.15 Grounding. (B) Type of Equipment Grounding Conductor. The equipment grounding conductor shall be an insulated copper conductor \
(C) Size of Equipment Grounding Conductor. The insulated copper equipment grounding conductor shall be sized in accordance with 250.122 but not smaller than 12 AWG.
(C) Size of Equipment Grounding Conductor. The insulated copper equipment grounding conductor shall be sized in accordance with 250.122 but not smaller than 12 AWG.
(D) Branch-Circuit Equipment Grounding Conductor. The insulated equipment grounding conductor for branch circuits shall terminate at a grounding terminal in a remote panelboard or the grounding terminal in the main service equipment.
(E) Feeder Equipment Grounding Conductors. Where a feeder supplies a remote panelboard, an insulated equipment grounding conductor shall extend from a grounding terminal in the service equipment to a grounding terminal in the remote panelboard.
 

Smart $

Esteemed Member
Location
Ohio
In most all cases with underground, direct buried or raceway method, where the EGC is required to be insulated it mostly has to do with corrosion protection than insulative properties. Earth can be and salt water is corrosive to copper... just not as fast-acting as with aluminum.

In the remaining cases, I do not know why an insulated EGC is required.
 

jap

Senior Member
The example I started with was insulating alum conductors in direct buried applications, that would be one example to protect the alum from the effects the soil would have on the alum conductors itself.

But I was really thinking of the other several examples of when an equipment ground conductor are required to be insulated.

One example would be a feeder from a central distribution to a agriculture building

547.9 Electrical Supply to Building(s) or Structure(s) from a Distribution Point. (D) Direct-Buried Equipment Grounding Conductors. Where livestock is housed, any portion of a direct-buried equipment grounding conductor run to the building or structure shall be insulated or covered copper.

In this example you could use UF cable because the copper equipment ground is allowed to be covered as opposed to being required to be insulated.

In this example seems to exclude alum equipment grounding even if it was insulated

Other examples would be equipment grounding in portions of article 680 along with

552.43 Power Supply.
a continuous green color or a continuous green color with one or more yellow stripes for use as the
552.43 Power Supply.power-supply cord
be identified by a continuous green color or a continuous green color with one or more yellow stripes.
(1) insulated, color-coded feeder conductors, one of which shall be an equipment grounding con four insulated, color-coded conductors
555.15 Grounding. (B) Type of Equipment Grounding Conductor. The equipment grounding conductor shall be an insulated copper conductor \
(C) Size of Equipment Grounding Conductor. The insulated copper equipment grounding conductor shall be sized in accordance with 250.122 but not smaller than 12 AWG.
(C) Size of Equipment Grounding Conductor. The insulated copper equipment grounding conductor shall be sized in accordance with 250.122 but not smaller than 12 AWG.
(D) Branch-Circuit Equipment Grounding Conductor. The insulated equipment grounding conductor for branch circuits shall terminate at a grounding terminal in a remote panelboard or the grounding terminal in the main service equipment.
(E) Feeder Equipment Grounding Conductors. Where a feeder supplies a remote panelboard, an insulated equipment grounding conductor shall extend from a grounding terminal in the service equipment to a grounding terminal in the remote panelboard.
I know what my explanation is for why the insulation of the equipment ground conductor what’s yours ?

I don't see where 547.9 above would exclude an aluminum equipment grounding conductor if it was insulated.


JAP>
 

david

Senior Member
Location
Pennsylvania
In most all cases with underground, direct buried or raceway method, where the EGC is required to be insulated it mostly has to do with corrosion protection than insulative properties. Earth can be and salt water is corrosive to copper... just not as fast-acting as with aluminum.

In the remaining cases, I do not know why an insulated EGC is required.
Utilizing insulation on an equipment ground for other than environmental effects would seem to target unintentionally elevating current on the equipment ground ( picking up stray current ) contact with a neutral bar in a sub-panel. Contact with other bare equipment grounds. An attempt to isolate a particular circuits equipment ground from being part of another circuits fault clearing path
 

david

Senior Member
Location
Pennsylvania
I know what my explanation is for why the insulation of the equipment ground conductor what’s yours ?

I don't see where 547.9 above would exclude an aluminum equipment grounding conductor if it was insulated.


JAP>
well, a insulated direct buried conductor might be USE and a covered direct buried conductor might be UF cable the section says insulated or covered copper

Edit if there was a comma after insulated it could read insulated conductor or covered copper, I'm I reading it wrong?
 

jap

Senior Member
well, a insulated direct buried conductor might be USE and a covered direct buried conductor might be UF cable the section says insulated or covered copper

Edit if there was a comma after insulated it could read insulated conductor or covered copper, I'm I reading it wrong?
What if the feed to the barn was single phase and I installed 3 Xhhw for the 2 hots and Neutral and a 4th for the EGC.
Would you fail me?


JAP>
 

david

Senior Member
Location
Pennsylvania
What if the feed to the barn was single phase and I installed 3 Xhhw for the 2 hots and Neutral and a 4th for the EGC.
Would you fail me?


JAP>
Are you saying all four conductors are insulated alum for a direct buried application?
Does the section say insulated or covered copper?
 

Smart $

Esteemed Member
Location
Ohio
Utilizing insulation on an equipment ground for other than environmental effects would seem to target unintentionally elevating current on the equipment ground ( picking up stray current ) contact with a neutral bar in a sub-panel. Contact with other bare equipment grounds. An attempt to isolate a particular circuits equipment ground from being part of another circuits fault clearing path
I considered that reason... and it truly does not hold up in most cases. Could be it's in the Code because others think of it same as you. The only time it holds up is when an isolated ground is justified. We see how that concept of IG receptacles has been relegated practically to dust, but there are still a few justifiable cases.
 

jap

Senior Member
Are you saying all four conductors are insulated alum for a direct buried application?
Does the section say insulated or covered copper?
I am, and, it does, so

so when you mentioned quote "In this example seems to exclude alum equipment grounding even if it was insulated".

????

JAP>
 

jap

Senior Member
yes I would read the section as requiring a copper equipment ground
547.9 Electrical Supply to Building(s) or Structure(s) from a Distribution Point. (D) Direct-Buried Equipment Grounding Conductors. Where livestock is housed, any portion of a direct-buried equipment grounding conductor run to the building or structure shall be insulated or covered copper.



Where in this sentence does it say it has to be copper?


JAP>
 
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