Garage and service upgrade rough inspection questions

WillK · 05-25-2011, 12:55 PM

Okay, so the inspector gave me a trench only so I can at least get my wife off my back about the trench, but I didn't get my service entrance approved. My mast out of rigid is not in his opinion adequately supported because he goes by the height of the weatherhead, not the height of the cable attachment LIKE THE POCO's MANUAL SAYS.

Fine, I'll brace it. I can figure that out.

His other complaint was that my XHWN feeder for the garage has to be in conduit all the way to the subpanel.

I am absolutely certain that code says it only needs conduit to the building entrance, he says that doesn't apply on individual conductors. This makes for a huge pain in the ass for me, can anyone give me some code references for if I'm right or he's right?

junkcollector · 05-25-2011, 01:12 PM

Quote:

Originally Posted by WillK

His other complaint was that my XHWN feeder for the garage has to be in conduit all the way to the subpanel.

I am absolutely certain that code says it only needs conduit to the building entrance, he says that doesn't apply on individual conductors. This makes for a huge pain in the ass for me, can anyone give me some code references for if I'm right or he's right?

XHWN conductors cannot be installed underground without a raceway. The only NEC compliant conductors are the ones that are also labeled USE. (UF cable also). Notice that it has to have a U in it for underground. The XHWN has a W in it, so it is listed for wet locations but not direct burial underground. You can find this info in article 310.13 (A) table- Conductor applications and insulations

busman · 05-25-2011, 01:49 PM

The correct question to answer is, "What Chapter 300 wiring method are you using?" A conductor is not a wiring method. For instance, UF cable can be installed as NM cable, but then it has to meet all the NM section requirements. XHWN is a conductor type, not a wiring method.

Mark

WillK · 05-25-2011, 04:20 PM

Quote:

Originally Posted by junkcollector

XHWN conductors cannot be installed underground without a raceway. The only NEC compliant conductors are the ones that are also labeled USE. (UF cable also). Notice that it has to have a U in it for underground. The XHWN has a W in it, so it is listed for wet locations but not direct burial underground. You can find this info in article 310.13 (A) table- Conductor applications and insulations

That's not the question, it is in 2" rigid conduit in the trench with a long radius elbow for the riser on each end going into a 2" LB fitting and then a 5" nipple to pass through the wall.

The question is about requiring the conduit to continue after enterring the building until it is inside the service panel.

So this presents a problem because inside my 2" conduit I have 3 conductors at 1/0 for the subpanel feeder, also I will have 3 conductors of 14 ga. THHN for my 3-way switch. I don't need these to go into the subpanel, but I guess if I have to do that and it's allowed I can.

For that matter, am I allowed to splice the 14 ga. THHN into NM-B cables inside the service panel, and if so is it okay to bond the NM to the service panel ground on each end even though same circuit but one would be bonded to a service panel other than the one from which the circuit originates? I mean, all the grounds are connected...

The problem is I can get my THHN for the run in 50' spoools, so 3 spools will be $33. If I have to get UF-B, I have to get it at $2.05 to buy by the foot and 50 feet is going to be $100+ or I get a 250' spool at $160.

Another question, I'm assuming this is yes, once I'm in the house if I have to run conduit, am I allowed to transition to EMT?

Edit to update: confirmed with AHJ (it's his office hours right now) that these are acceptable.

As for the service mast bracing, I'm planning to do my bracing based on this:

http://www.electriciantalk.com/f9/he...er-mast-10341/

So I'll take some EMT tubing and flatten the ends to make the bolt attachment, attach to the clamp at the top and the roof at the bottom using a carriage bolt. 2 braces in a V shape... I saw something about required angles at some point for guy wires so if I can find that I'll make sure that my angles are in that kind of range unless anybody else has any other guidelines to offer.

sirsparksalot · 05-25-2011, 04:34 PM

Will, in your blog, you itemized your costs. This is an interesting FYI for me. Can you tell me what the Ext. means?

ITEM COST EA QTY EXT. COST
2" rigid conduit $53.57 4 $214.28
2" weather head $10.50 1 $10.50
4/0 SEU cable $2.50 20 $50.00
Halex wire holder $9.28 1 $9.28
superstrut $17.97 1 $17.97
3/8" lag screws $0.85 2 $1.70
washers $0.81 1 $0.81
wedge anchors $11.98 1 $11.98
3/8" spring nuts $3.99 1 $3.99
1/4" spring nuts $3.99 1 $3.99
1/4" grade 8 bolts $0.81 4 $3.24
2" pipe strap for superstrut $3.34 1 $3.34
1-1/2" pipe strap for unistrut $2.97 1 $2.97
3/8" square washers $3.66 1 $3.66
meter can $45.38 1 $45.38
2" meter hub $6.25 1 $6.25
2" dia 5" nipple $4.86 3 $14.58
2" lock nuts $1.39 1 $1.39
NOALOX anti-corrosoion grease $5.93 1 $5.93
ground lug $2.09 3 $6.27
#4 bare copper wire $24.63 1 $24.63
$6 bare copper wire $0.68 15 $10.24
ground rods $31.99 3 $95.97
1/0 THHN $0.95 150 $142.50
100A main breaker panel $48.97 1 $48.97
2" LB pull fitting $19.47 2 $38.94
2" long radius elbow $15.33 2 $30.66
Core drill rental $66.00 1 $66.00
conduit ground clamps $5.27 2 $10.54
$885.95
$939.11

WillK · 05-25-2011, 04:55 PM

I originally made the list in excel so it lined up better in the spreadsheet, my columns were description, price each, quantity, and Ext is price times quantity. I think it stands for something like extended, so it has something to do with the line item total.

I'll be adding a few lines to my list!

the last 2 lines by the way are total and then total with 6 percent sales tax included.

NJMarine · 05-25-2011, 08:04 PM

These conductor are required to be in conduit all the way to the subpanel
You can install a 2 inch tee and reduce the size of side opening to 1/2 and bring the 12 wire out in conduit to switch box.
The switch box would have to a fs orsimilar box.

Jim Port · 05-25-2011, 09:49 PM

As NJM said, conduit systems need to be complete between terminations like boxes or pull points. Individual conductors need to be in a conduit or raceway. They cannot be used in free air.