Building Ground Question

[tricountytrail]

Wondering how and if anyone grounds the metal (skin) of the building or is this is required?

Lighting protection?
Insulate a potential hot wire from electrical wiring from energizing metal and becoming a shock hazard?

 

[Norcal]

If it was metal framing and the panel was attached to metal framing it will all be bonded together.

 

[hermetic]

The UK has a regulation which states that all extraeneous metalwork must be earthed. It would be normal practice to earth the metal frame of the building, and by attaching metal siding to the frame, it would also be earthed. Any metal construction that has electrical equipment attached to it, or running inside it should be earthed, in the same way that a metal conduit is earthed. Even if you use metal conduit bolted to the frame of a building, which would earth it, still best to have a seperate heavy earth cable attached to a ground electrode or grid. In this way any circuit protection fuses or breakers will be instantly activated if the electrical potential of the building rises above 0V due to a fault.
YMMV!

 

[wyliesdiesels]

Wondering how and if anyone grounds the metal (skin) of the building or is this is required?

Lightening protection?

Insulate a potential hot wire from electrical wiring from energizing metal and becoming a shock hazard?

Any metallic pathways that should not be energized are required to be bonded to prevent becoming energized.

What kind of framing do you have?

Lightening protection is done with ground electrodes or UFERs...

 

[tricountytrail]

Any metallic pathways that should not be energized are required to be bonded to prevent becoming energized.

What kind of framing do you have?

Lightening protection is done with ground electrodes or UFERs...

It is a normal 6x6 wood pole barn with metal siding and roof.
Electric service is 4 conductor ( 2 hots neutral and ground) sub panel from main box. So question it to bond the metal of the outside of building (to panel box or to its own earth ground with ground rod and bonding wire)

 

[wyliesdiesels]

It is a normal 6x6 wood pole barn with metal siding and roof.
Electric service is 4 conductor ( 2 hots neutral and ground) sub panel from main box. So question it to bond the metal of the outside of building (to panel box) or to its own earth ground with ground rod and bonding wire)

It needs to be bonded to the panel.

You should already have 2 grounding electrodes connected to the panel ground bar. Or a UFER electrode.

A grounding electrode will not provide a low impedance fault current pathway. Do not confuse grounding electrodes and equipment grounding conductors. Theyre 2 different animals.

Also you do no want an isolated grounding electrode...

 

[ard]

I recalled that metal siding only needs to be bonded if it MAY BECOME ENERGIZED. Not 'all metal siding must always be bonded'. No?

 

[wyliesdiesels]

What defines may become?

 

[tricountytrail]

It needs to be bonded to the panel.

You should already have 2 grounding electrodes connected to the panel ground bar. Or a UFER electrode.

A grounding electrode will not provide a low impedance fault current pathway. Do not confuse grounding electrodes and equipment grounding conductors. Theyre 2 different animals.

Also you do no want an isolated grounding electrode...

You should already have 2 grounding electrodes connected to the panel ground bar.
The ground for this subpanel is at the main panel 150 ft away 2 ground rods and tied to main water line (which is code) This is the ground for the electric panel and all wiring which is isolated from the metal roof and siding for the most part. Concern would be if building got struck by lighting or hot leg of power energized the metal roof or siding.

 

[tricountytrail]

I recalled that metal siding only needs to be bonded if it MAY BECOME ENERGIZED. Not 'all metal siding must always be bonded'. No?

Looking for a little more detail?
I don't recall this being addressed anywhere?

 

[mcbane]

STRUCTURAL metal needs to be bonded if it may become energized, and metal siding is typically not structural. But some cities and counties require siding to be grounded anyway. As a practical matter, any metal that is exposed and will ever be near an electrical circuit or temporary extension cord may become energized and you might want to consider grounding it, even if not required to do so by NEC.

 

[tricountytrail]

STRUCTURAL metal needs to be bonded if it may become energized, and metal siding is typically not structural. But some cities and counties require siding to be grounded anyway. As a practical matter, any metal that is exposed and will ever be near an electrical circuit or temporary extension cord may become energized and you might want to consider grounding it, even if not required to do so by NEC.

and metal siding is typically not structural
Thanks the outside outlets are gfi and the building is spray foamed and the inside metal is not exposed so I believe I'll call it good.

 

[Cmreschke]

For those saying to bond the skin of the building, got an nec article number? Do you guys also bond aluminum siding, window trim, and gutters?

The skin does not require a bond, imo.

 

[Stuart in MN]

For those saying to bond the skin of the building, got an nec article number? Do you guys also bond aluminum siding, window trim, and gutters?

The skin does not require a bond, imo.

I don't have my current edition of the NEC at home, but this is from the 2008 edition, Article 250.116 FPN: "Where extensive metal in or on buildings may become energized and is subject to personal contact, adequate bonding and grounding will provide additional safety."

The way I interpret that is it may not be necessary, but it's not a bad idea to do so, plus it should be simple enough to accomplish.

edit: bonding structural metal is covered in Article 250.104, along with metal piping.

 

[Cmreschke]

I don't have my current edition of the NEC at home, but this is from the 2008 edition, Article 250.116 FPN: "Where extensive metal in or on buildings may become energized and is subject to personal contact, adequate bonding and grounding will provide additional safety."

The way I interpret that is it may not be necessary, but it's not a bad idea to do so, plus it should be simple enough to accomplish.

FPN's were not ever enforceable, and the term has been changed to informational note. So you're right, not necessary.

 

[fitter30]

Have a metal roof on a stick built house which each side of this modified A frame is 24x50 should this be grounded?