Attaching MC cable to steel building

[jgorm]

What kind of fasteners are you guys using to attach MC cable to the girts? I read on one thread that MC is no allowed from 0-8' above the floor. Is that true? I saw these magnet things (mag daddy) at the electrical supply house and they seem cool, but expensive.

Can I use sticky tabs that accept zip ties?
Should I use screw in holders with sheet metal screws?

Is there any NEC rules that say when I need to use a metal box vs a plastic box for light switches and plugs? I bought a number of each because the nail in plastic will work where I have wood framing, but I'd like to mount a plastic box for my light switches because I use Insteon switches and metal will eliminate their RF function. The metal boxes look cooler and I like the screw wire clamps better than the plastic box pinch clamps.

If they say i need GFCI in the garage, do I need them on the ceiling that controls my lights too? Seems a bit crazy to me, but it wouldn't surprise me.

 

[zmaxmotorsports]

Buy some emt and a bender,start practicing box offsets and 90s.Unless you want to frame everything in wood.

 

[rockwithjason]

Mc must be protected from physical damage where Exposed. Height makes no difference. Zip ties and sticky backs wont cut it as the cable must be securely fastened. Terminating mc in a plastic box must be done i accordance with the boxes listing. Most arent listed to terminate mc.

 

[Stuff]

MC is not OK for when exposed to physical damage. Rules vary by locations - up to the inspector.

It is close to impossible to find a plastic box that will work with with MC or EMT.

GFCI protection is required for all receptacles. If you have plug-and-cord connected ceiling lights then put a GFCI blank face next to the switch that feeds it.

 

[jgorm]

Awesome info! Thanks a ton. It seems like MC really doesn't have any advantage over NM-B wire, maybe just the disadvantage of being harder to work with. I'll feed the lights off a GFCI that I was going to put next to the switch.

What are the rules for the plastic flex conduit? I have a ton of that from a previous project. Is that equivalent to EMT as long as it's properly secured? I know it wont look as nice, but I'm already WAY over budget and that's why I have to do the electrical myself.

 

[_Dock_]

You can run mc in the ceiling and most inspectors won't have a problem with it, then transition to a 4" box then run straight down with emt. If you use Minnie's then your offsets will be limited.

If it was me I would just use emt, buy a 1000 foot spool of #12 b,w,g and have at it. Run a half loop trunk line going each direction from your panel then branch off with T's for your lighting and receptacles. Just be careful and make sure you are meeting the fill and derating requirements.

 

[Norcal]

NM & MC both have the same limitation requiring protection from physical damage. Is the " plastic flex conduit" ENT, AKA "Smurf tube"?

ENT = Electrical Non-Metallic Tubing.

ENT is IMHO a PITA & can be a ****** to get a fish tape through, there are other reasons not to use it.

 

[rockwithjason]

Ent is not equivalent to emt. Is must also be protected from physical damage and will is generally not compatible with the plastic nail on boxes you want to use. What is killing you is the need for the plastic box. Mc with steel boxes is easy. Romex with plastic boxes is easy. Mix and match is harder

 

[jgorm]

Mc with steel boxes is easy. Romex with plastic boxes is easy. Mix and match is harder

Thanks guys. This is my new plan. Metal boxes with MC in the shop area, and romes and plastic in the finished office.

 

[jgorm]

I returned my roll of 12/2 MC and bought 10 sticks of 0.5" EMT, 10 sticks of 0.75", a ton of fittings, 500' of each color 12g, and metal boxes. Tack on another $500 in materials! At least it will look more professional. I'm keeping the 14/2 MC for the lights and transitioning on my girt about 10' off the ground. This will make things easier for future expansion. I already had a 0.5" bender and now I need to get the .75" bender.

The "protected from physical damage" clause always gets me. Does that include ramming with 1000lb carts full of metal, pushed at full speed? Ax swinging mad men?

I dont need any type of wire clamps going into and out of the panel or metal boxes when using EMT right? I just install the EMT screw clamp and I'm good to go?

 

[alfredeneuman]

I dont need any type of wire clamps going into and out of the panel or metal boxes when using EMT right? I just install the EMT screw clamp and I'm good to go?

You'll need a strap within 3' of any termination (box, panel, or fitting such as an LB), and then one every 10' feet thereafter.

 

[jgorm]

You'll need a strap within 3' of any termination (box, panel, or fitting such as an LB), and then one every 10' feet thereafter.

But nothing inside the junction boxes to clamp the wires?

So on a 10' run from j-box to j-box I would have to strap the EMT within 3' of each box, but nowhere else?

 

[alfredeneuman]

But nothing inside the junction boxes to clamp the wires?

So on a 10' run from j-box to j-box I would have to strap the EMT within 3' of each box, but nowhere else?

Nothing inside the boxes to clamp the wires.......... and yes

 

[jgorm]

Great! Thanks for all the help. I want the inspector to come in and think, that guy did it right and sign off on everything.

 

[gs8212]

I'm planning power in my own homeowner garage and have clarifying questions. Assume everything will be GFCI protected.

1. So, as long as the wire is in the walls and ceiling of the home garage, I should use NM and plastic boxes because the wall is my protection?

2. But if I run power say exposed on the ceiling of the garage it needs to be protected by running it inside EMT?
3. Is that gray plastic tubing acceptable or is that a question for the inspectors?

Thanks much. The GJ is an I credible resource. Wish I had some knowledge to contribute. [emoji4]

 

[Alchymist]

I use metal boxes wherever possible. Why? Where is the most likely hot spot if a problem occurs? That's right, wire nut or other termination. Where are the wire nuts & other junctions? Right again - in the box.What happens? The bad junction gets hot. Plastic doesn't like heat.... draw your own conclusions.

PS: Plastic boxes won't cause a breaker trip if a wire comes loose and touches, a properly grounded metal box will.

 

[gs8212]

PS: Plastic boxes won't cause a breaker trip if a wire comes loose and touches, a properly grounded metal box will.

Excellent advice Alchymist. I'm a believer in not being pennywise and pound foolish. I also like to do it right and forget it, if at all affordable. Metal versus plastic seems very prudent without a lot of addition cost IMHO.

Is my assumption correct regarding inside the wall considered protected?

Greg

 

[rockwithjason]

1. So, as long as the wire is in the walls and ceiling of the home garage, I should use NM and plastic boxes because the wall is my protection?

yes, the wall serves as the protection

2. But if I run power say exposed on the ceiling of the garage it needs to be protected by running it inside EMT?

emt is one way to go, another is mc cable

3. Is that gray plastic tubing acceptable or is that a question for the inspectors?
where pvc conduit is used for physical protection it must be schedule 80. emt is often easier to get, easier to work with and looks much better
Thanks much. The GJ is an I credible resource. Wish I had some knowledge to contribute. [emoji4]

in the future, be cautious of hijaking a thread. if you only have a few related questions as in this case then you are probably ok but if you get too far away from the op's topic you need to start your own thread. you will get better answers that way too.

 

[gs8212]

.....be cautious of hijaking a thread...... [emoji481]

Will do. [emoji4]