Utility penitration violating air control?
My electrician tells me that he must cut a 2 inch hole through my wall to bring electrical service into my house. He also tells me I must not foam around the wires that go from the exterior service panel to the interior fuse panel. He says not to worry about air sealing “because there is a service box on either side” of the 2″ gaping hole! When I pointed out both service boxes are not sealed he said that I am drinking the building science Kool-aid and he sees this whole air barrier thing as a cult following of sorts. He says there is nothing in his code book that suggests it is best practices when I showed him several advanced building books speaking to the importance of air control in building assemblies. Have any of you other cult members who spend inordinate amounts of time and money to create a tight house ever experienced this problem and what should I do about this penitration since I do think electrical service brought into my house may prove useful?!
Andy
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Replies
Hi Andy,
This site (http://www.quickflashproducts.com/products_electrical.html) sells penetration seals for this type of situation. I suggest mounting one (and ordering a spare) and instructing the electrician to use it for making his connection. It's your house and you are paying for his services. If he refuses or damages the seal out of spite, hire a new electrician.
How about some electrician's "plug duct seal"? It's basically made for this application (...sorta). https://www.homedepot.com/p/Gardner-Bender-1-lb-Plug-Duct-Seal-Compound-DS-110/100212441
Yep, the 'cult of building science' haha. I suppose as a consulting electrical engineer I'm a cult of efficiency for the electrical industry too :-) New stuff has always had some resistance I suppose, but the end results can be seen in more comfy homes and lower heating/cooling bills so there are tangible benefits.
In the commerical world, it is a common requirement to fire stop everything, which is very similar to air sealing. If your electrician has done commercial work, he should be familiar with how to do that. If he resists foam, use duct seal on the exterior (if exposed), or, if he has a box on either side with a nipple between, there are expanding cable grommets made for sealing pipes around cables. These are common in the telecommunications industry, but your electrican probably won't be familiar with them. See here for some examples: https://www.comstarsupply.com/innerduct-and-conduit.html
A sheet of fire barrier putty will make a good air seal and shouldn't cause any problems for an electrical installation if installed neatly.
Note that at my own home, I have a 2" conduit between the exterior meter can and my indoor transfer switch (for my generator). It has three 90 degree fittings in it and is probably around 8-10 feet total length. I didn't bother to seal the inside (I did foam around the conduit though), and it DOES have a slight draft through the conduit, but it's barely noticeable. A shorter run will allow more air to pass through due to less resistance to airflow.
Bill
The QuickFlash product is nice because it can be integrated into the WRB before the cladding goes on. The siding guys can leave the 2" hole for the conduit. The electrician then simply has to pull the conduit through the QuickFlash grommet.
As far as the code books go, this is from the 2018 IRC:
N1102.4 (R402.4) Air leakage (Mandatory). The building thermal envelope shall be constructed to limit air leakage in accordance with the requirements of Sections N1102.4.1 through N1102.4.5.
The various I-codes are all in sync with this requirement. Even though electricians typically live in National Electrical Code world, they still must comply with the overall building codes when they modify aspects of the building structure. All of this depends on what codes are in force in your jurisdiction.
>" they still must comply with the overall building codes when they modify aspects of the building structure. "
This would mean they have to seal around the conduit itself. This wouldn't mean they have to seal INSIDE the conduit. Once you're inside the electrical stuff itself, electrical code / UL / NEMA / etc. prevail.
It would be worth putting this in on the request form in the back of the NEC codebook though. As far as I know, there is no current requirement in the electrical code to air seal anything except in hazardous locations (think gas stations, refineries, those kinds of places).
BTW, DO NOT let the electrician use a "sealoff" here. Those are permanent, filled with a resin. They are a one-shot deal. You don't want that in a typical residential setting where you might have to do service work someday. I mention this because these might be the only electrical air sealing products an electrician will be familiar with.
Bill
I’m a little curious how an electrician can tell you that you’re wrong (and drinking cult koolaid instead of presumably, being reasonable like them) and expect to keep the job.
Matt,
I share your curiosity.
Because the electrician holds the permit, and to replace the electrician part way through the project will be costly in a standard labor market. The market right now is rather tight, and the electrician knows this. The OP probably needs the electrician more than the electrician needs the OP, so the electrician is not going to be bothered by something he does not understand/believe, etc.
The advice above about using putty pads is the same as what I was going to suggest. Cheap and easier than arguing with the electrician.
Given all the potential penetrations and other aspects of the house that are affected by the electrical installation, this (hopefully early) discussion would be a huge red flag for me. We had some bad experiences with our remodel electrician that sounds like your guy - he ignored several of our very specific instructions because "he knew better". Well, we were right. It can can be difficult, expensive, and frustrating to deal with someone who has an agenda different than yours. If you have a choice, it may be a lot less painful to find an alternative early in the process. I'm not saying it won't be painful, only that it may be less painful ...
I've found that some of the air sealing resistance can be overcome with "I don't want bugs crawling in here either." It avoids the "house has to breathe" arguments, and really...who wants bugs inside their house?
Also, +1 on using the putty and looking for a new electrician.