Steel Trusses and Conductors

[Mathew Hawley]

I was inspecting a steel frame home. While in the attic space i noticed the electrical conductors for the house lying along the edges of the steel trusses.

My thoughts were that if one was in the attic and stepped on a wire just right and sliced it it would charge the whole attic.
When running wires in attics with steel frame trusses is there anything required to protect conductors from getting damaged/cut

[gbeaumont]

Hi Matthew,

Yes those conductors should be protected from any potential damage with either, bushings, conduit or a nailer attached to the steelwork. As you have stated this setup has the ability to energize the framing.

Regards

Gerry

[Mathew Hawley]

Thanks Gerry

[Speedy Petey]

First off, metal framing should be bonded. This will prevent any chance of "energizing" it.

Second, yes, if passing through holes in the framing there must be protection. If the cables are just laying across the outside of the framing, and they are well away from the scuttle hole, and clear of being stepped on, there is no protection required.

[tdietrich1]

Is the attic designed to be commonly accessed?

tom

[Marc D. Shunk]

Got any pictures? I'd like to see what the attic of a steel framed dwelling might look like.

[Mathew Hawley]

I do not have pictures, however there were wires at the scuttle entrance and around the air handler unit.

I was also given this information:

250.104 Bonding of Piping Systems and Exposed Structural Steel.
- - (C) Structural Steel. Exposed structural steel that is interconnected to form a steel building frame and is not intentionally grounded and may become energized shall be bonded to the service equipment enclosure, the grounded conductor at the service, the grounding electrode conductor where of sufficient size, or the one or more grounding electrodes used. The bonding jumper(s) shall be sized in accordance with Table 250.66 and installed in accordance with 250.64(A), (B), and (E). The points of attachment of the bonding jumper(s) shall be accessible.

Thank you all for your replies.

[Barry Adair]

Metal framing is an excellent conductor of electricity. Therefore extra caution shall be observed too avoid contacting energized electrical conductors (wiring) when entering or working in the subject property attic space for equipment servicing or other purposes. Never install service or storage platform materials atop the electrical wiring.

If anyone is dumb enough to directly contact, step on or stand on wiring, no matter the location they may deserve the consequences.

Thinning of the gene pool is necessary in certain cases.

[tdietrich1]

Found this: http://www.mikeholt.com/videodisplaynew.php?pageid=4328

250.104(c) There is a comment about metal studs, and requirements.

tom

[Greg Fretwell]

Florida has added bonding steel studs to the building code but the NEC does not require it.
I can see where it would be likely that an inspector would require all RX in the attic of a steel framed building to be secured. They are pretty conscientous in this county about making sure ALL wiring in the attic is secured before the ceiling drywall goes up. If you see loose RX it was put there after the FEPAC. Steel trussers are still pretty rare here so the wiring is going to be laying on wood truss chords. Where it comes through the steel wall members it is required to be in grommets and also draft stopped.

[Greg Fretwell]

Steel studs are not "structural" steel. They have virtually no load bearing capability in the guage you see in residential construction. A load beraring wall will still be wood.

[Mathew Hawley]

Thomas,
very helpful video.

Thanks everyone for your input.

[Mathew Hawley]

Here is a intresting video/story

http://www.local6.com/money/7302637/detail.html

[Barry Adair]

Originally Posted by Greg Fretwell

Steel studs are not "structural" steel. They have virtually no load bearing capability in the guage you see in residential construction. A load beraring wall will still be wood.

Check IRC R603

I think that disputes your statement and the home in my photos complies, no wood except for blocking or backing.

[Mathew Hawley]

Hello Greg,

I looked at the home under construction next to the one i inspected. It was steel frame all the way around, including all interior walls. The only wood was the roof sheathing.