I'm looking at running a new main line to upgrade my electrical service to 200 AMP and using some 2" metal conduit run horizontally for 12' on a sided house. What's the proper way to do it? This will have siding around it on the house

I'm worried mostly about flashing details. Does the pipe need to be extended away from the wall? Should I use blocking to hold the screws / pipe away from the wall so the siding can fully go underneath. What attention should be paid to the screw holes? Am I overthinking this? Do the screw holes need to penetrate the siding, or is there a safe way to slide the siding around without causing water problems.

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    What type of conduit are we talking about here? Also, by "power main" do you mean some type of service conductor? Commented Jun 7, 2017 at 4:04
  • Yes as ThreePhaseEel asked. The type of conduit determines the spacing of support. Any type of steel conduit would only take 2 supports if spaced properly but PVC may need another support according to its listing. The type of support would be by approved means.
    – ArchonOSX
    Commented Jun 7, 2017 at 8:51
  • Hopefully that's more details. The mechanical / electrical details I feel I've got down pretty well already.
    – RLZaleski
    Commented Jun 7, 2017 at 10:45
  • We still need to know what type of conduit is being used (PVC has this habit of doing the worm on you if you don't fit expansion joints, and the fitment of expansion joints influences where the supports go) Commented Jun 7, 2017 at 11:41
  • Do you have the option to fit the conduit so that it's not where there will be siding?
    – Tester101
    Commented Jun 7, 2017 at 12:06

2 Answers 2


Reading your question and comments I am assuming you are trying to install a service drop to a meter. In that case you would want it to be as short as possible and use GRC. I am not sure if you can read the image or not but if you use 2" GRC you can use that as an unsupported riser for the drop any other conduit you may wind up installing a support bracket. That's what I am trying to show you in the image below. enter image description here Remember I said it should be as short as possible. Generally what we try and do is get down to the meter and in this case install a 200A enclosed breaker. Then from there you can run to a main lug only panel and from there you can use any allowable conduit EMT, PVC, etc. Because it is exposed to sunlight over 10' on the exterior you need to factor in derating per NEC Article 310.15 (B)(3)(c). Also Article 310.15 (B)(3)(a) exception will allow you to use Type XHHW-2 insulation on you conductors and you do not have to derate.

Finally in your comment you mentioned an AEP engineer disallowed a run over the garage. Are you sure you have to move the meter? In the state I am in we are allowed to raise the service drop to meet overhead clearances. enter image description here These images are from the Oncor book which is our utility company in this state. I don't know which utility you are using or where you are but I am pretty sure they have something similar to this. If it were me I would make sure that the engineer would just allow you to readjust the drop to meet the modern clearances before I would start the project you are proposing.

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    Thanks, aepohio.com/global/utilities/lib/docs/builders/meter/… which is what I must meet. Looking at it, I can either go 10 feet vertical then 15 feet horizontal, or 30+ feet vertical to go over the roof. The advantadge of the horizontal is I don't have to break through the eave. It seems you're advocating for purely vertical. Still doesn't answer my main question of flashing. Do I mount the conduit directly to the Tyvek, should I add aluminum behind for rain protection, or should I use blocking so the pipe is a few inches out.
    – RLZaleski
    Commented Jun 7, 2017 at 19:12
  • I understand your question. The problem lies is you are asking if you should use flashing and then you ask if you should use blocking and if the siding should go underneath the conduit. So there's confusion on my part to visualize through text what is actually being asked. Maybe if you edited your question and attached a small sketch or a picture of the existing situation we as a group could give you a more complete answer. Thanks Commented Jun 8, 2017 at 12:55

If you are installing the siding after the service conduit I would consider attaching trim board to the framing and attach the conduit to the trim board.

Then flash the siding out over the trim board on the top for drainage and add J-channel on the underside of the trim board.

This is a little more obvious, maybe even objectionable depending on where it is mounted and who is looking at it, but it alleviates the problems with penetrating the siding or adding the siding after the service conduit.

I will post a picture of what I did on my outbuilding later.

Good luck and stay safe!

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