How did you run panel wiring thru your roof?

CVN-71 · September 2009

Question, after panel wires are connected to MC1 10AWG wiring, what is the best/preferred way to run this wiring(along with ground wire) to the combiner box in the attic under the panels? Leak proofing it as well. Thanks!

tallgirl · September 2009

Re: How did you run panel wiring thru your roof?

CVN-71 wrote: »

Question, after panel wires are connected to MC1 10AWG wiring, what is the best/preferred way to run this wiring(along with ground wire) to the combiner box in the attic under the panels? Leak proofing it as well. Thanks!

You need to make sure there is proper flashing starting UNDERNEATH the roofing material (shingles, shakes, whatever). There are plumbing "stack" seals and other products that can be used to seal around a penetration. What you do NOT want to do is try sealing above roofing material -- you need to start below the roofing material, get a good seal there, THEN replace the roofing materials above that.

I'd draw a picture, but you can look at the plumbing "stacks" and vents and see plenty of examples.

It goes without saying that any conduit you run through the roof needs to be up-slope from where the wires enter that conduit.

CVN-71 · September 2009

Re: How did you run panel wiring thru your roof?

Thanks. Is there any reason I cannot run the wire into the Ridge Venting? Ridge venting is a thick breathable matting with slots, on the peak of the house, which is then capped by shingles. In theory I could remove 1 shingle cap, drop the wires through the slots, and replace the shingle over the wires. The only reason this wouldn't work is if it was against code. Any thoughts?

Almost done pounding the 8' grounding rod into the ground. Three feet to go! Living in the Granite State has it's disadvantages.

icarus · September 2009

Re: How did you run panel wiring thru your roof?

What is the matter with a conventional weather head, pipe and flashing?

Tony

nigtomdaw · September 2009

Re: How did you run panel wiring thru your roof?

If your earth rod is going into rock then maybe one single rod may not be enough, I live on a rock outcrop and used six rods with one inch copper tape bonding them to gether at 8 ft intervals then backfilled the trench with soil. Just a thought.

mike95490 · September 2009

Re: How did you run panel wiring thru your roof?

CVN-71 wrote: »

Almost done pounding the 8' grounding rod into the ground. Three feet to go! Living in the Granite State has it's disadvantages.

There is a thread here, about UFER grounding systems, but you need to plan it before you pour the concrete.

http://forum.solar-electric.com/showthread.php?t=3583&highlight=ufer

CVN-71 · September 2009

Re: How did you run panel wiring thru your roof?

I'm pretty sure I'll be able to pound it all the way in, it's just slow going. I haven't hit a slab of granite yet, I shouldn't since I'm 2 feet from the foundation and that's mostly fill. I'm watering the hole letting the water seep in for about an hour, that makes the rod drive easier. Should have it all the way in tomorro... I hope.

Cariboocoot · September 2009

Re: How did you run panel wiring thru your roof?

Grounding is a bit trickier than just pounding an 8' rod in the ground. NEC requires that as a minimum, but how well it works comes down to soil conditions. In wet loamy soils that we have up North here, 5' of rod will actually work. The dryer the soil, the more contact with it you need to get an efficient ground. Sand/gravel/rock is very hard to get to conduct. Low water saturation is another problem. Checking to see how good your ground conductor is once installed is a whole 'nother kettle of fish.

And I wouldn't put holes in any roof if it can be avoided. "Over the edge and through the soffit" is better, so to speak. Less likely to develop a leak anyway.

dwh · September 2009

Re: How did you run panel wiring thru your roof?

CVN-71 wrote: »

I'm pretty sure I'll be able to pound it all the way in, it's just slow going. I haven't hit a slab of granite yet, I shouldn't since I'm 2 feet from the foundation and that's mostly fill. I'm watering the hole letting the water seep in for about an hour, that makes the rod drive easier. Should have it all the way in tomorro... I hope.

If you find that you can't get it hammered all the way in - do NOT cut off the extra that is sticking up above grade.

Proper ground rods have a stamp on them near the top, and if you cut it off inspectors will notice.

If you get stuck, rent one of these - it makes driving ground rods painless:

http://www.toolbarn.com/bosch-11304.html

Just remove the bit and set the jack hammer on the end of the ground rod. If the rod starts to bend under the pressure, slip a piece of pipe over it to keep the above-ground part of it straight while you hammer it in.

n3qik · September 2009

Re: How did you run panel wiring thru your roof?

Can not do the wire though the ridge vent. The wire must be in a metallic conduit from the roof to the first fuse/circuit breaker box if you go though the attic.

VolcanoSolar · September 2009

Re: How did you run panel wiring thru your roof?

CVN-71 wrote: »

Almost done pounding the 8' grounding rod into the ground. Three feet to go! Living in the Granite State has it's disadvantages.

I live in the lava state, and cannot imagine pounding my ground rod 8' through the lava. How the heck do you do it? I can't imagine the rod not getting all battered at the pounding end. Mine needs to go in soon.

tallgirl · September 2009

Re: How did you run panel wiring thru your roof?

icarus wrote: »

What is the matter with a conventional weather head, pipe and flashing?

Tony

Besides being ugly as sin that high up a roof?

Having a woman around means you get that "woman's touch". It also means -- do not suggest something that is as ugly as all get out.

CVN-71 · September 2009

Re: How did you run panel wiring thru your roof?

n3qik wrote: »

Can not do the wire though the ridge vent. The wire must be in a metallic conduit from the roof to the first fuse/circuit breaker box if you go though the attic.

Can you please explain this more? I'm a newbee so bear with me. Isn't the wiring with the MC2 connectors the type that is UV rated for open air and doesn't have to be in conduit? At what point after the connection at the panels is conduit required?

Thanks

n3qik · September 2009

Re: How did you run panel wiring thru your roof?

The wire with the MC connectors is good for connecting the panels together and to the combiner box. For the most part, these wires are under the panels and mounting rails so they are protected from physical damage. When you go from the combiner box to the inverter/etc. These wires are run in a conduit. This does two things. One, lets you use cheaper wire. Two, the conduit protects the wires from physical damage.

This is how I did the wiring on the shed. I bent the rules a little by using gray PVC instead of metal. This is under one of the solar panels.

dwh · September 2009

Re: How did you run panel wiring thru your roof?

VolcanoSolar wrote: »

I live in the lava state, and cannot imagine pounding my ground rod 8' through the lava. How the heck do you do it? I can't imagine the rod not getting all battered at the pounding end. Mine needs to go in soon.

As I mentioned in a previous post in this thread - rent a Bosch electric jackhammer.

As for the end being "peened" - I look on that as a good thing...if the ground clamp somehow comes loose (knocked loose usually) then as long as it's not broken it's less likely to slip off the end of a well-peened ground rod.

Also, inspectors look at the peening. A rod that has little or no peening might either A) be only 3 feet in the ground and then sawed off and dummied up when it was too tough to hammer it in, or

gone in really easy and might have too high a resistance.

CVN-71 · September 2009

Re: How did you run panel wiring thru your roof?

n3qik wrote: »

The wire with the MC connectors is good for connecting the panels together and to the combiner box. For the most part, these wires are under the panels and mounting rails so they are protected from physical damage. When you go from the combiner box to the inverter/etc. These wires are run in a conduit. This does two things. One, lets you use cheaper wire. Two, the conduit protects the wires from physical damage.

This is how I did the wiring on the shed. I bent the rules a little by using gray PVC instead of metal. This is under one of the solar panels.

Your setup is basically what I thought I could do, except using the ridge vent hole instead of drilling a conduit hole. The panels will be connected in series (2 panels each string and the string will be hooked by MC2 connector to a #10 AWG USE-2 sunlight-resistant cable. My combiner box will be in the attic directly below the panels. So I need to run six #10 AWG USE-2 cables to the combiner box. Rather than drill a hole in the roof, these cables can easily slip through a ridge vent. The the distance from "protected" area of panels to the ridge vent is about 6-8" this is the amount of cable that will be "exposed". I'm confused that since this cable is sunlite resistant, why it needs to be in Conduit on the roof. On the attic side of the roof it will be in conduit from where it enters the attic to the combiner box. Does this make sense.

VolcanoSolar · September 2009

Re: How did you run panel wiring thru your roof?

dwh wrote: »

As I mentioned in a previous post in this thread - rent a Bosch electric jackhammer.

As for the end being "peened" - I look on that as a good thing...if the ground clamp somehow comes loose (knocked loose usually) then as long as it's not broken it's less likely to slip off the end of a well-peened ground rod.

Also, inspectors look at the peening. A rod that has little or no peening might either A) be only 3 feet in the ground and then sawed off and dummied up when it was too tough to hammer it in, or gone in really easy and might have too high a resistance.

I saw your other post after I'd already sent mine -- what a great idea. And -- I even own a Bosch electric jackhammer, which I've given up on for doing my eletrical trench, it would take days and days at the rate it was going, but I can't wait to try it for this purpose. THANKS.

Brock · September 2009

Re: How did you run panel wiring thru your roof?

CVN-71, that is how I wired my panels. I just used 50 foot MC "extensions" and cut them in half. Then I ran them up and in through the ridge vent. Then from the attic side I simply pushed on some flex conduit right up to the ridge vent and ran that back to the combiner box. I am not saying it is to code, but everything was close to the ridge vent and why add another hole in the roof?

My only concern long term is when the roof has to be re-done because more of the MC cable will be exposed, although the panels will have to be moved at that point anyway...

lotek · September 2009

Re: How did you run panel wiring thru your roof?

there is no reason I know of that you couldn't run your wiring through a ridge vent, or any other flashed roof vent for that matter. You would want to run it through a conduit to protect it from physical damage. Gray PVC is ok for outside, metal is required inside.

icarus · September 2009

Re: How did you run panel wiring thru your roof?

tallgirl wrote: »

Besides being ugly as sin that high up a roof?

Having a woman around means you get that "woman's touch". It also means -- do not suggest something that is as ugly as all get out.

I'm not sure whether or not to take offense at that,,,lol.

Perhaps ugly as sin, but they do make smaller weather heads, and quite possibly it is the only "legal" entry system that is weather tight, ugly or not!

T

dwh · September 2009

Re: How did you run panel wiring thru your roof?

icarus wrote: »

and quite possibly it is the only "legal" entry system that is weather tight, ugly or not!

T

Sorry, picky I know, but weather heads are not generally weather "tight". They have a phenolic/plastic insert with assorted sizes of knockouts. You knockout the hole just larger than the wire. There is normally no rubber gasket or other sealing device.

That's why you always need drip loops with a weather head.

icarus · September 2009

Re: How did you run panel wiring thru your roof?

dwh wrote: »

Sorry, picky I know, but weather heads are not generally weather "tight". They have a phenolic/plastic insert with assorted sizes of knockouts. You knockout the hole just larger than the wire. There is normally no rubber gasket or other sealing device.

That's why you always need drip loops with a weather head.

You're absolutely right, a weather head in and of itself is not rain tight, but with proper gasketing and drip loops it is the only way that I know that is a "legal"entry.

T

solartek · September 2009

Re: How did you run panel wiring thru your roof?

Several other "legal" methods of roof penetrations were discussed in this thread.

Scott.

CVN-71 · September 2009

Re: How did you run panel wiring thru your roof?

Great info, I think I'm going to go with the Soladeck, it's pretty much what I need, combiner, roof enclosure with flashing. Clean install. I'll change my plans a bit. I already have a Midnite Combiner box, which I was going to put in the attic but I'll use that down the road when I expand with a pole mount array. The Soladeck will be perfect for roof mount. I checked out the Soladeck installation instructions, pretty simple. I'll combine the panel wiring in that, then run my 2awg wire from that down to the power center.

Thanks again for the help everyone!

Oh yea, ground rod is all the way in, 3" below ground level! The water "lubrication" method worked real well. Had my daughter's boyfriend pound the last 18". I may add a second rod just to make make him work a bit more. :-)

tallgirl · September 2009

Re: How did you run panel wiring thru your roof?

icarus wrote: »

I'm not sure whether or not to take offense at that,,,lol.

You know you've been insulted by a woman when you aren't quite sure you've been insulted

Perhaps ugly as sin, but they do make smaller weather heads, and quite possibly it is the only "legal" entry system that is weather tight, ugly or not!

T

As others have pointed out, there are plenty of code-compliant ways to make that transition. The harder part is making sure the solution is truly water tight with respect to the roof.

newenergy · September 2009

Re: How did you run panel wiring thru your roof?

690.31 (E) Direct-Current Photovoltaic Source and Output Circuits Inside a Building. Where direct-current photovoltaic source or output circuits of a utility-interactive inverter from a building-integrated or other photovoltaic system are run inside a building or structure, they shall be contained in metal raceways, or metal enclosures, from the point of penetration of the surface of the building or structure to the first readily accessible disconnecting means. The disconnecting means shall comply with 690.14(A) through (D).

I don't know if you need this anymore. When I use the Soladeck I come into the bottom from the attic with a piece of EMT and use an EMT to Flex fitting in the attic and then run the wires through flex until maybe they go back outside near the inverter and back into EMT.

As far as just running the DC wiring into the roof outside of a metal enclosure/conduit you have the problem of 690.31 and also one of the few things inspectors around here always look for is they don't any direct contact between PV wiring and roofing material.

How did you run panel wiring thru your roof?

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