NEC Access and 240V Question

[mustang68408]

Long time follower first time poster...

I have a town house in FL that I am currently investigating adding a 240v 30amp circuit and outlet in my garage to support some additional equipment for auto service. (i.e. air compressor, MIG welder, etc.)

I just want to add a single outlet. My fuse panel is located in my single car garage on the West wall. It's a flush mount and the garage was finished by the original home builder w/ drywall and baseboard (and it wasn't a model surprisingly enough). I am wanting to have my 240v outlet on the East wall. The garage has a bedroom above it so there is no attic so Romex is out of the question. I am considering running flexible conduit or PVC conduit with 8ga THHN wiring from the electrical panel to the outlet.

My questions are:
-Using conduit I assume I'm going to have to mate that to the electrical box so this will require me cutting drywall out to attach the conduit, correct?
-Can I run the conduit through the drywall and then secure the conduit with anchors or to the studs to run it up the wall, across the ceiling and down the other wall? (Putting in the correct 90 degree elbows when necessary)

This is probably more of a local law question, but if anybody in Tampa, FL is out there you might be able to answer:
-How about permitting? Do I have to get a permit to add an additional circuit since it wasn't installed when the house built before installation and/or inspection?
-Also, what's does the average electrical inspection cost? (Or is it necessary when I go to sell the house)

I am researching the NEC for this application and I'm a bit reluctant to spend 80-100$ (70$ digital) on a book and I am wondering if the nfpa.org website (requiring sign up of course) would give me access to the information about what I need to do to make this happen.

Thank you!

 

[Charles (in GA)]

Simply put, the NFPA is in the business of making money. Anyone who disputes that is not on their mailing list!. I am bombarded almost daily by mailings for membership, brochures for various fire safety and other courses they put on around the country, books they sell, and on and on. This is all the result of my purchasing the 2011 code book (thru Amazon) and then signing up with NFPA for a free digital copy (PDF) of the code, personalized with my name at the top of each page (so I cannot print it off or make a digital copy of it) to give to anyone else.

You would find the code, by itself, quite useless to you. It is not the easiest thing in the world to understand, until you have been through it many times.

My recommendation is to buy the code, and a book that explains the more important features of the code in a understandable way. My suggestion for an accompanying book is "Illustrated Guide to the National Electric Code" by Charles Miller. There are editions for all of the more recent versions of the NEC. And yes, Yikes!!! that stuff has become pricey. The Illustrated guide is $83.38 and the NEC in paperback is $89.50 plus shipping from NFPA. It appears that Amazon (themselves) no longer even carries the NEC, and I noticed that prices from other sources listed on Amazon had a note after them "price set by the publisher". Even more proof that the NFPA is simply after the money.

With all of that said, you need to find out for your locale, and I do mean the exact area you live in, such as the incorporated city, or the county if not in the city limits, when permits are needed and the particulars of them.

Not sure how you intend to get wire, conduit or anything else across the garage from one side to the other, if it is all sheetrocked. Do you mean you are going to run surface mounted conduit across the ceiling? Be aware, with an attached garage, you are dealing with firewalls. Probably double layer of sheetrock on the ceiling and any wall adjoining the house. Any penetrations of these walls needs to be properly fire sealed.

Easiest path would be to come out of the top of the circuit breaker panel, and then S the conduit thru the wall and exposed up the sheetrock, across the ceiling and then down the other side, all exposed. You would need to seal the opening where the conduit passes thru the sheetrock, and if you use PVC, you will need lots of mounting clamps as it is very prone to sagging, especially in the Florida heat.

Charles

 

[theoldwizard1]

First, if it is a townhouse, there are likely rules that would cover doing your own "home improvements". Check into that.

Technically you should pull a permit which will include the inspection. This could cost anywhere from $50-$200 depending on your town. If you are going to pull a permit, discuss your plans in details with an inspector (usually in the same office where you get your permit).

Code books are for professionals. Buy a "How To" book at your home improvement store.

The tricky part is the transition between the conduit mounted to the wall and the drywall and short wiring behind the dry wall.

Install an "old work" electrical box in the same stud bay as your panel. This will alo be flush to the drywall. You will need a cover like the one below to attach the conduit to. Feed one end of your NM (Romex) wire (10/2 w/ground) through the cover and the old work box into the breaker box (with an appropriate clamp). Connect an entrance elbow with a ****** to the cover. Use sweeps to make the corners at the ceiling.

Plastic conduit usually takes more "brackets" to support it on horizontal runs.

Likely your compressor and your welder will have different plugs. NEMA 6-30 would be reasonable.

 

[Mustang51js]

All you need to do is run a peice of romex up the wall a foot from the box inside the wall, put a junction box on outside of Sheetrock, from there you can run pipe up and over to other side. I would just do it and if there's an issue when you sell just take it back out. If your in over your head just call a local electrician to do it, prob cost you $300

 

[mustang68408]

All great information, thanks for the NFPA heads up and I'll check out my local hardware store.

I've seen the various NEMA plugs on the hardware and the thought never ran across my mind...

All you need to do is run a peice of romex up the wall a foot from the box inside the wall, put a junction box on outside of Sheetrock, from there you can run pipe up and over to other side. I would just do it and if there's an issue when you sell just take it back out.

Not a bad idea, this isn't a permanent residence for me anyway but I'm trying to make the auto repair I do a lot easier. Turning wrenches isn't all that fun in 90+ degree heat 6 months out of the year, trying to make life easier w/o sacrificing safety and potential resale of the property.

 

[Charles (in GA)]

Aw, come on guys, what you are suggesting is to put Romex in pipe.......... someone will come along any time now to tell us that you cannot do that but if you know the code, you know its OK to pipe Romex, so long as you respect fill requirements.

Charles

 

[mustang68408]

Aw, come on guys, what you are suggesting is to put Romex in pipe.......... someone will come along any time now to tell us that you cannot do that but if you know the code, you know its OK to pipe Romex, so long as you respect fill requirements.

Charles

I think down here you have to pipe THHN and Romex can only be routed through attic areas or behind sheetrock... at least that was said at the electrical supply store I visited.

 

[theoldwizard1]

Aw, come on guys, what you are suggesting is to put Romex in pipe.......... someone will come along any time now to tell us that you cannot do that but if you know the code, you know its OK to pipe Romex, so long as you respect fill requirements.

Charles

Yeah, I was wondering if I would get away with that !

What size conduit is required for 10/2 Romex. 3/4 or 1" ?

 

[Beemer533]

I'm not sure if he was suggesting running Romex the whole way.. Just run the romex as said into the surface mounted Junction box, then from there pull THHN to the outlet.

Connect the romex and THHN with wirenuts and you are done.

Just don't forget to seal any penetration with the appropriate fire rated caulk.

For what it is worth, I would use 3/4 emt, not pvc; less clamps means less holes. Assuming you have a clear shot and don't need to bend anything like saddles to go around obstacles it will be pretty straightforward.

 

[mustang68408]

I'm not sure if he was suggesting running Romex the whole way.. Just run the romex as said into the surface mounted Junction box, then from there pull THHN to the outlet.

Connect the romex and THHN with wirenuts and you are done.

Just don't forget to seal any penetration with the appropriate fire rated caulk.

For what it is worth, I would use 3/4 emt, not pvc; less clamps means less holes. Assuming you have a clear shot and don't need to bend anything like saddles to go around obstacles it will be pretty straightforward.

Yeah I was pricing out the 3/4 emt and yes it's a straight shot. I would install the 90 degree couplers such as

where the wall meets the ceiling.

Yeah plus I agree with the previous poster about the PVC it gets pretty warm and I don't want it to sag.

Anything special with the wire nuts and connecting the Romex to THHN? Or just the plane jane nuts and twist

 

[Beemer533]

Yeah I was pricing out the 3/4 emt and yes it's a straight shot. I would install the 90 degree couplers such as

where the wall meets the ceiling.

Yeah plus I agree with the previous poster about the PVC it gets pretty warm and I don't want it to sag.

Anything special with the wire nuts and connecting the Romex to THHN? Or just the plane jane nuts and twist

Not really, I would look, but I think you might need the red wirenuts. They will tell you the allowed capacity (how many wires of what AWG allowed per wirenut) on the package.

Also, since you will be using metal now, make sure you connect the ground conductor in each box..

Those elbows are fine, they'll keep the conduit tight to the ceiling in the corners. Assuming you aren't using a bender, I would pick up an offset for each box so the conduit will lay flat.

 

[mustang68408]

Not really, I would look, but I think you might need the red wirenuts. They will tell you the allowed capacity (how many wires of what AWG allowed per wirenut) on the package.

Also, since you will be using metal now, make sure you connect the ground conductor in each box..

Those elbows are fine, they'll keep the conduit tight to the ceiling in the corners. Assuming you aren't using a bender, I would pick up an offset for each box so the conduit will lay flat.

Ah good point on the offset, I was considering the bender, but I think the straight piping will be cleaner.

I'll make note of the ground connector...

Thanks!

 

[bczygan]

Free 2011 NEC online. Download the PDF file.

https://archive.org/details/gov.law.nfpa.nec.2011

Read the 2014 edition online free (NFPA70):
https://www.nfpa.org/Login

 

[mustang68408]

Thank you, might as well peak through it even though it may read like Japanese

 

[theoldwizard1]

I'm not sure if he was suggesting running Romex the whole way.. Just run the romex as said into the surface mounted Junction box, then from there pull THHN to the outlet.

Your ARE pemitted to run Romex inside of conduit as long as you do NOT exceed the fill requirements.

 

[mustang68408]

Your ARE pemitted to run Romex inside of conduit as long as you do NOT exceed the fill requirements.

Ah cool, thanks for clearing that up...

 

[Charles (in GA)]

To determine fill, you need to take the cable being used and measure its diameter. If it is oval rather than round, use the MAJOR diameter and assume it is round, calculate the area in square inches using the old "pie are square" formula (or a calculator on the internet) and then look at tables that list the max fill for various sizes and types of conduits.

(9) A multiconductor cable or flexible cord of two or more conductors shall be treated as a single conductor for calculating percentage conduit fill area. For cables that have elliptical cross sections, the cross-sectional area calculation shall be based on using the major diameter of the ellipse as a circle diameter

Max fill percentage is 53% for one conductor (if you are using a Romex type cable) or 31% for two conductors, or 40% for more than two conductors.

A couple of examples are EMT (Electrical Metalic Tubing) ½" 53% fill is .161 sq/in and ¾" 53% fill is .283 sq/in.

Schedule 40 rigid PVC conduit has slightly lesser max fill at .151 sq/in and .269 sq/in for ½ and ¾ respectively.

Three quarter conduit should work fine for the installation in using 10/2 w/grd Romex®

Charles

 

[Beemer533]

Your ARE pemitted to run Romex inside of conduit as long as you do NOT exceed the fill requirements.

This is true, I guess I just try not to make it a habit.. I prefer pulling THHN through conduit anyway...

 

[theoldwizard1]

This is true, I guess I just try not to make it a habit.. I prefer pulling THHN through conduit anyway...

If you have it on hand, sure. It is probably a bit easier to pull and you might be able to go down a size on the conduit.

If you are buying wiring for the job, why buy 2 different kinds for an install like this ?

 

[Beemer533]

That does make sense.. I guess not everyone has a few thousand feet of THHN hanging around their garage

 

[Charles (in GA)]

If you are planning on using THHN and EMT, there is no reason to use anything larger than ½". You can put up to five 10 gauge THHN conductors in a ½ EMT conduit.

If you have it on hand, sure. It is probably a bit easier to pull and you might be able to go down a size on the conduit.

If you are buying wiring for the job, why buy 2 different kinds for an install like this ?

Not to mention the extra splices/wirenuts are simply another place to have problems.

Charles