Hello,

I am currently in the middle of digging a trench from my house to my garage, in order to wire the garage. What I would like to know is this: I live in NYC, which frowns upon the use of PVC in electrical work (i.e. no Romex, PVC boxes, non-metallic conduit, etc.), so I'm assuming I cannot do the run using Schedule 40 PVC; I will probably have to use conduit. What are the general requirements for running conduit underground? I have read the relative chapter/section in several different books about home wiring, and I'm getting mixed signals: some say rigid conduit only, while others say IMC is also acceptable; some say threaded fittings only, some say fittings with watertight bushings, etc. - you get the picture; it feels like a bunch of alphabet soup.

So what's the cheapest/easiest (note: "cheapest" is more important than "easiest", since I don't mind a little elbow grease if I can save a couple of bucks) way to do this? Can I use IMC, or do I have to use rigid conduit? What about threaded fittings: is there a way around using them? I'd hate to use threaded fittings, since that would mean having to get a store to cut and thread the conduit for me in advance, instead of being able to make this up as I go (and it will probably also be expensive to get them cut/threaded, too).

If I do have to use threaded RMC, here's another question: Lowe's sells 10' lengths of RMC with pre-threaded ends - one end has male threads, the other has female threads. Is this what I want? Also, how do I get them to thread it for me - should I take the pieces over to the area where they thread galvanized steel water pipes and black iron gas pipes (i.e. is it the same thread pattern)? That would make it a lot easier, since they claim that they cut and thread galvanized/black steel pipes for free, so maybe they'd do it for RMC, too.

And one more question (this one is probably only for those who are well-versed in the NEC): I have a document from the NYC Department of Buildings about the NYC Electrical Code. The document is formatted as follows: it is basically a listing of article numbers, and amendments to that particular article. Here's a random example:

110.31
Revise the second sentence of the second paragraph of section 110.31 to read as follows:
A fence shall not be less than 8 ft (2.44m) in height.

So can anyone please tell me the article number(s) in the NEC dealing with underground cable, so that I can look for any relevant amendments in this document? And while we're at it, how about the article number for the usage of different types of cable (metallic vs. non-metallic) - can you tell me that as well? It's well know that Romex may not be used in NYC, only BX; I'd like to track down exactly where it says it.

Thanks very much in advance,
Moishe

What, you can't read the code? Or understand it? Small illustration of what us electricians must do every day, read, understand, and implement the code, which reads like a law book, oh that's right, it is a law. Want to have some fun? Have an attorney read the code, what a hoot!


Never had a reason to view this code, NYC did a fine job of amending the NEC 2002 edition, which they currently adopt.

Permits? We dont need no stinking permits! as quoted by Lewis on the Drew Cary show.

However you need to have the actual NEC 2002 code book opened to understand what NYC is amending. So if I show you a section for a particular answer, the NEC code is not visible to you, only the NYC code.

And there is not one small section in the NYC code that explains what can and cannot be used, because they refer to each of the NEC articles they want to change. So each wiring method is a separate article, and that means someone must have the NEC book opened , and follow the NYC code to see what they change, add or delete.




Direct buried cable is not allowed as per text in bold:

300.5(A) Revise subsection 300.5(A) to read as follows:
51
(A) Requirements. Direct-buried cable or conduit or other raceways shall
Be installed to meet the minimum cover requirements of Table 300-5.
Direct buried cable shall not be installed except by special permission
from the Commissioner of Buildings.

AND

340.10(1) Revise the first sentence of subsection 340.10(1) by deleting the words "including direct burial in the earth."




This entire section explains where Romex can and cannot be used:

334.10 Revise section 334.10 to read as follows:
334.10 Uses Permitted. Type NM, Type NMC, and Type NMS cables
Shall be permitted to be used in the following:
(1) One- and two-family dwellings.
(2) Multifamily dwellings, except as prohibited in Section 334.12.
(3) Cable trays, where the cables are identified for the use.
52
FPN: See Section 310.10 for temperature limitation of conductors.
334.12(A)(1) Revise subsection 334.12(A)(1)to read as follows:
(1) In any multifamily dwelling exceeding three floors above grade
334.12(A)(11),(12) Add two new subsections 334.12 (A)(11) and 334.12(A)(12) to
Read as follows:
(11) In other than residential buildings of three floors or less.
(12) In commercial buildings.
334.30(C) Delete subsection 334.30(C) in its entirety.



Article 300 of the NEC is what dictates general methods and includes a depth chart. Article342 is IMC, Art 344 is RMC, Art 352 is RNC or PVC conduit and these are not amended by NYC.

So, seems that PVC installed min 18" deep is allowed. Sch 80 PVC is considered as tough as RMC, and is used in high traffic areas. Other wise for a residential application in a lawn with no traffic, SCH 40 is allowed, min 18 " deep.

So, I see that RMC, IMC, and PVC is allowed for underground installations, and no UF cable is allowed , ever, at all, anywhere.

I think I addressed most of your concerns, if I missed something, let me know.

Quote:

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Originally Posted by tkrussell

NYC did a fine job of amending the NEC 2002 edition, which they currently adopt.

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I guess that's easy for you to say, since you don't work in NYC. :D:D:D
I have heard more than one professional electrician complain about how lousy the NYC local codes are. But that's just their two cents...

Quote:

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Originally Posted by tkrussell

Permits? We dont need no stinking permits! as quoted by Lewis on the Drew Cary show.

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I know, I'm not planning on getting a permit. But I want to do it right anyway for two reasons: 1) I don't want anybody getting hurt or killed after the next rainfall due to my work; and 2) in case something bad happens, I don't want the insurance company to be able to say "it wasn't done according to code! We're not paying! Nyah, nyah nyah nyah, nyah!!!!"

Quote:

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Originally Posted by tkrussell

However you need to have the actual NEC 2002 code book opened to understand what NYC is amending. So if I show you a section for a particular answer, the NEC code is not visible to you, only the NYC code.

And there is not one small section in the NYC code that explains what can and cannot be used, because they refer to each of the NEC articles they want to change. So each wiring method is a separate article, and that means someone must have the NEC book opened, and follow the NYC code to see what they change, add or delete.

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That's not a problem; once I have the right article numbers, I can write them down and proceed to the reference section at my local library.

Quote:

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Originally Posted by tkrussell

Direct buried cable is not allowed as per text in bold:

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Yeah, I already found that part; that's why I only mentioned PVC and metallic conduit in my first post, and not UF.

Quote:

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Originally Posted by tkrussell

This entire section explains where Romex can and cannot be used:

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I found that also, and that part puzzles me: it is a well-known fact (almost an urban legend) that Romex + PVC boxes cannot be used in NYC. Everyone who's the least bit handy knows this; employees at the local electrical supply stores will tell you this; and the local Lowe's and Home Depots don't even carry Romex cable by the foot like other wire (although they do have a couple of shrink-wrapped, precut rolls for sale in case you need it for whatever reason). Additionally, in all the houses I've worked on (quite a few), I have NEVER seen Romex being used (no matter how old or new the house was, and no matter how many or how few stories tall it was) - it's always either BX or conduit, and (obviously) always metal boxes. So something doesn't seem to add up here. Am I missing something?

Quote:

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Originally Posted by tkrussell

So, seems that PVC installed min 18" deep is allowed. Sch 80 PVC is considered as tough as RMC, and is used in high traffic areas. Other wise for a residential application in a lawn with no traffic, SCH 40 is allowed, min 18 " deep.

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Strange... like I said, I've never seen or heard of PVC being used, but if you say so, then SCH 40 it is (it's going in my backyard).

Quote:

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Originally Posted by tkrussell

I think I addressed most of your concerns, if I missed something, let me know.

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Thanks for all your help so far. Now that I know I can use PVC, it's easier on the wallet (and thus, on the mind ;)). This raises a couple of questions though:

1) Is there a specific size of PVC I should be using?
2) How do I run the wires: individually, directly in the PVC? Using Romex? BX? O should I just run a piece of inexpesive EMT inside each piece of PVC? I'm a little worried about the PVC not being grounded, y'know - in case a wire breaks and/or water somehow does get into the pipe, it can result in some nasty circumstances.
3) Do I connect the PVC the same way I would for plumbing drainage, or is there a special breed of fittings/connectors for electrical runs?
4) When considering conduit, I had planned on using LB fittings when coming out of the ground and into each building. How do I make the transition from under the ground to inside the building if using PVC?

Thanks again,
Moishe

1.Conduit size will depend on size and quantity of wire pulled through.

2.After the conduit system is all installed, fittings and all, then pull through individual wires, typically THHN/THWN or XHHW insulated wire.

3.Electrical PVC conduit is gray and must be UL listed. There are all the fittings necessary for a complete raceway. Be sure to use electrical sweeps, not plumbing 90 deg fittings, or any plumbing fittings at all.. All the parts are glued use PVC cement.

PVC is plastic, it does not need to be grounded. You will pull through a separate green ground wire to continue the ground to the device in the garage. And no matter what you do, water will collect in the conduit. Because of this the code requires that weep holes be drilled into the conduit at low points to allow water to drain. And the wires must be with insulation rated for wet locations, such as THHN/THWN and XHHW. The W represents for wet locations.

4.Not sure I understand, an LB is used to make a hard 90 deg turn. If you use one to aim the conduit down into the ground, once it rises, use one to trun 90 deg into the building. Once inside the building, the conduit can continue to its destination, or stop at a junction box and change over to cable.

As far as I see the code is as I explained. Not to say if you were to speak with an inspector that he may impose his own interpretation. And most contractors may not want to argue with him.

Arguing with an inspector is like wrestling with a hog in mud, after a while you realize the hog loves it.

The insurance company will come down on just as hard once it is learned that the installation was not permitted, and if any losses are incurred the installer becomes completely liable, for civil and criminal charges.

Print out the entire NYC code amendment and bring it along with you to the library, find the NEC 2002 edition, and follow it through article by article. Having the code open is the only way to read this document.

Quote:

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Originally Posted by tkrussell

1.Conduit size will depend on size and quantity of wire pulled thru.

2.After the conduit system is all installed, fittings and all, then pull thru individual wires, typically THHN/THWN or XHHW insulated wire.

3.Electrical PVC conduit is gray and must be UL listed. There are all the fittings necessary for a complete raceway. Be sure to use electrical sweeps, not plumbing 90 deg fittings, or any plumbing fittings at all.. All the parts are glued use PVC cement.

PVC is plastic, it does not need to be grounded. You will pull thru a separate green ground wire to continue the ground to the device in the garage. And no matter what you do, water will collect in the conduit. Because of this the code requires that weep holes be drilled into the conduit at low points to allow water to drain. And the wires must be with insulation rated for wet locations, such as THHN/THWN and XHHW. The W represents for wet locations.

4.Not sure I understand, an LB is used to make a hard 90 deg turn. If you use one to aim the conduit down into the ground, once it rises, use one to trun 90 deg into the building. once inside the building, the conduit can continue to its destination, or stop at a junction box and change over to cable.

As far as I see the the code is as I explained. not to say if you were to speak with an inspector that he may impose his own interpretation. And most contractors may not want to argue with him.

Arguing with an inspector is like wrestling with a hog in mud, after a while you realize the hog loves it.

The insurance company will come down on just as hard once it is learned that the installation was not permitted, and if any losses are incurred the installer becomes completely liable, for civil and criminal charges.

Print out the entire NYC code amendment and bring it along with you to the library, find the NEC 2002 edition, and follow it thru article by article. having the code open is the only way to read this document.

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nyc only allow metal (not emt) pipe in burial... only see them use gavl or alum and romex is not allow only use bx

Quote:

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Originally Posted by caibuadday

nyc only allow metal (not emt) pipe in burial.... only see them use gavl or alum and romex is not allow only use bx

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Yes, I know all that. My question is (a) why does NYC have to adopt a "holier-than-thou" approach and make electricians' lives more difficult, and (b) how come it doesn't say anything about that in the document I mentioned?

Quote:

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Originally Posted by PalmMP3

Yes, I know all that. My question is (a) why does NYC have to adopt a "holier-than-thou" approach and make electricians' lives more difficult, and (b) how come it doesn't say anything about that in the document I mentioned?

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safety... safety safety... safety safety ( like altenate parking; does any other city have that)... I havenot come across bury emt or plastic... you could do rigid pipe with compress /thread fitting

tkrussell,

Long story, made short, I've decided to go with ½" rigid metallic conduit, despite the fact that it is more expensive. Can you advise me on this, please? For starters, to I have to use use threaded fittings, or can I use some type of compression fittings? If I use threaded fittings, should I put teflon tape on the threads for some added insurance? And what about moisture in the line - does RMC require something like the "weep holes" you mentioned? And can I get away with a shallower trench (location is residential backyard, little or no foot traffic)?

Also, some general questions about the project: does the underground run have to be GFCI protected before leaving the house, or can I put in GFCIs where it enters the garage? And once inside the garage, can I use EMT and regular boxes, or am I still confined to using "outdoor" materials?

Thanks again,
Moishe

Quote:

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Originally Posted by caibuadday

safety.....safety safety.....safety safety ( like altenate parking; does any other city have that)....

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Yeah, I know, alternate side parking is a load of BS, not unlike many regulations in NYC. Although I HAVE seen alternate side parking in other cities as well.

Quote:

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Originally Posted by caibuadday

i havenot come across bury emt or plastic........ you could do rigid pipe with compress /thread fitting

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I know. EMT can never be used; plastic is hit or miss, depending on local codes. Since plastic seems to be so controversial around here (not to mention that the local stores around here don't sell RNC unless you special-order it), I'm sticking with RMC for now.

tkrussell,

One more thing: the run is about 40 feet long. It starts by exiting the side house, makes an immediate 90 degree turn toward the backyard, goes about 22 feet, makes another 90 degree turn, and then goes another 17 feet or so, at which point it hits the garage. So my question is: I'm assuming that it's better to use sweeps for the two underground turns, correct? Even though using pull-elbows might make it easier? Also, a friend of mine has a ½" conduit bender that he uses for EMT; will that bender work for RMC as well, or does RMC require a special bender?

Thanks again,
Moishe

Seems I missed one of your posts, so I will answer here and catchup.

Do not use pulling ells underground, these must be accessible, and are not rated to be buried.

The path you explain, if I understand correctly, will use 4 - 90 Deg sweeps. This is the maximum of bend in one conduit , point to point, box to box, etc. 360 Degrees is the max.

When pulling wire through, use an approved wire lube, or "soap" to reduce the friction of the wire inside the pipe. Do not use motor oil, laundry soap, or Palmolive.

You can fit a max of 9-#12 THHN/THWN wires in this pipe. Sounds as if you are only installing one circuit, needs 3 #12 wires. If you need more than 5 or 6 wires ,I would be using a larger conduit, as the more bends in a conduit causes more friction, and allows for easy pulls.

Use only stranded wire, take my word for it, you will find soild wire a few pennys cheaper, once you pull solid you will wish you splurged for stranded.

A larger conduit will allow for any added expansion later, this is up to you and if there is any remote chance you may need more circuits or power later.

Thread as many couplings and fittings that you can. Make all wrench tight. At the points threading is difficult, then you can use rigid threadless compression connectors or couplings, again wrench tight. Do not use pipe dope or teflon, this will break the continuity of the conduit.

Take note, if this conduit is for only 1 residential circuit, at a max of 20 amps 120 volts, and does not cross paved areas, you can use an exception to bury the conduit 12 inches.

Weep holes are much more difficult with rigid steel conduit, because of the burrs the drill will leave inside, and will cut the insulation on wire. For this installation I would not worry about weep holes, only with large conduits or very long runs.

A 1/2 " EMT one shot bender will only fit 1/2" EMT. Generally speaking the next size larger of EMT benders fit rigid conduit, so you will need a 3/4" EMT one shot bender for 1/2 " Rigid. You may even note on the bender it will state this. A true rigid hand bender is called a "Hickey", and looks more like a hook, and takes some training and knack to use, as a Hickey bends small amounts at one time, you must bend a little move the bender and bend some more, until your bend is complete. Full 90 D sweeps can be made with any size radius, but does take time to learn. Use the factory sweeps for this.

If you use manufactured sweeps, and all other runs are straight, you can do this with out the need to bend. All depends on the planning of your run.

The wiring in the pipe does not need to be GFI protected, so use the GFI receptacles at the garage. And once inside, EMT or cable will be fine, no need for rigid here.

I thnk I have addressed all your concerns, if I missed something, get back and we can go from there.

Quote:

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Originally Posted by tkrussell

The path you explain, if I understand correctly, will use 4 - 90 Deg sweeps. This is the maximum of bend in one conduit , point to point, box to box, etc. 360 Degrees is the max.

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That's correct - two sweeps where the path of the circuit turns, and (obviously) another one at each building penetration (where the conduit goes from vertical to horizontal). Just curious, though: supposing I needed to make more turns underground; how would I beat the 360 degree limit?

Quote:

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Originally Posted by tkrussell

When pulling wire thru, use an approved wire lube, or "soap" to reduce the friction of the wire inside the pipe. Do not use motor oil, laundry soap, or Palmolive.

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How much lube do I put on? Do I put lube only on the end of the wires, or do I squirt it all along the entire wire, or what?

Quote:

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Originally Posted by tkrussell

You can fit a max of 9-#12 THHN/THWN wires in this pipe. Sounds as if you are only installing one circuit, needs 3 #12 wires.

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Actually, I'm planning on at least two circuits (it can't hurt to have the lights and receptacles on separate circuits, especially since we may someday decide to add a motorized garage door opener; besides, if they're on opposite legs, they can share a neutral). I was even toying with the idea of running #10 (or even #8, although it probably wouldn't fit too well) wire and making a little subpanel for the garage circuits inside the garage.

Although I'm puzzled by your statement "one circuit, needs 3 #12 wires." Shouldn't it need only two wires (hot and neutral), since the conduit body acts as the ground?

Quote:

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Originally Posted by tkrussell

Use only stranded wire, take my word for it, you will find soild wire a few pennys cheaper, once you pull solid you will wish you splurged for stranded.

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A pity - I have two 100-foot rolls of #12 solid that I'm trying to get rid of. :( I guess I'll have to try the harder way first; if it doesn't go, I'll have to splurge on stranded.

Quote:

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Originally Posted by tkrussell

Thread as many couplings and fittings that you can. Make all wrench tight. At the points threading is difficult, then you can use rigid threadless compression connectors or couplings, again wrench tight.

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Can I use any couplings marked "Rigid Conduit" and "Compression", or do I have to pay through the nose for the kind marked "Liquid-Tight", with the rubber/plastic pieces inside?

And now, some additional questions:
1) Can RMC be cut with an ordinary pipe cutter, or do I have to use something more serious like a hacksaw or Dremel?
2) Is there an inexpensive do-it-yourself method for threading conduit, or am I stuck paying $80 for a hand-held threader set, or paying a store to do it for me?

Thank you once again for your patience. I really appreciate it!
Moishe

Let me preface by saying, I run electricians now, and I am passing the everyday practices we normally do for a quality installation that is practical and reasonable cost, and either meet or exceed code.


Ok, here in order:

1.You don't beat it, ever. UG installations are difficult. Commercial work we set down a handhole, those flat plates you see that say Electric, or rise on a wall or pole and install a junction box. This rule is never bypassed. Try pulling wire through more than 360 d , believe me I have seen it done, by intention and accident. You can pull the conduit out of the ground there can be that much friction.

2. There is no measured amount, try to coat the wires evenly as it enters the conduit, squirt some down at the entrance.

3. #8 is out can only fit 3 wires in 1/2 " can fit 6- #10. But 1/2 " is only used for 3-6 #12, more than that we use larger conduit.

4. For a quality circuit, at .04 per ft for wire, a separate supplemental ground/green wire is now pulled by most contractors.

5.Any fitting must be metal and is only for rigid conduit. Liquidtite is a flexible raceway.

6. You can use a pipe cutter, you must absolutely ream each cut end very well to remove the burr.

7.No short cut to threading, only threadless fittings. They are costly but sometimes really need them or for a run that can benefit from using a few to not need to thread, but in any case it is expensive.