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Alonzo 05-10-2012 01:08 PM

Attic fan
Hey guys, I am going to install a fan in the attic. I live in San Antonio and I have a few questions. Do I need to run the line to the fuse box outside or can I tap into a power source nearby? Do I need to have a switch in the attic to cut power? I went to the city to get a permit and tried asking one of the inspectors but they were busy and this is some info I need to put into the drawing for my permit. I am no electrician as you can guess but I can do it with some help. Thanks in advance for any help or advice.

kok328 05-10-2012 04:15 PM

Either make an appointment with the inspector or go back an wait for a moment of his time. Only they will be able to tell you what they will be looking for in you locality.

AndyGump 05-10-2012 05:17 PM

Why are you installing an attic fan?
Are you having moisture (condensation) problems?


CallMeVilla 05-11-2012 06:33 PM

Oh my . . . You went to the City for a permit to install an attic fan? Do you crave punishment?

1. You can mount to fan at a vent location in the wall.
2. Find a junction box that is accessible nearby and tap the power. If it is very full, you might consider a different box . . . but it does not seem you have the experience to trace devices on the circuit.
3. Most attic fans have thermostat controls which cycle the fan on and off depending on the temperature. You need to switch.
4. Do all this in the extreme cool of the AM because when I did it , it was 80 degrees outside and 100 degrees in the attic.

Good luck and try to stay cool.

nealtw 05-12-2012 12:36 PM

Inexperienced person getting a permit or talking to the permit dept. is always a good idea. They would also talk to him about proper seal on attic access and pluging every hole that could draw air from living space or crawl space, like every hole that wires are pulled thru.

CallMeVilla 05-12-2012 11:52 PM

An inexperienced person can get a lot of help from sourves OTHER TAHN the City Permit Dept. Those guys live on the fees they generate. IN my City, they are literally a profit center . . . they get paid based on fees generated. Honestly, do you think it is necessary to get a permit to change a receptacle? They do.

There are a lot of handymen or retired contractors out there who could advise a homeowner for free.

I wouldn't go to the City unless the work being done was so significant it might harm the ability to re-sell it at a later date.

nealtw 05-13-2012 09:40 PM

Villa, I have no problem helping someone with there job, that is what this site is about. But quick easy answers are not always what is needed. Andy started by asking a question and hasn't recieved an answer, I would bet he was just getting started. With a fuse box outside, the first question might be how old is the house. Is there a possibility he has knob and tube. Do we know how many amps this fan draws and how many may be availible at what ever box he has access to. You may have a problem with inspectors I am sure a lot of people do but there main job is still there especialy with wiring, they save lives.

Alonzo 05-15-2012 12:29 PM

Hey guys, I still haven't been able to talk to an inspector. I've gone a few times but they are always busy on something else. I will keep trying. To answer some questions and give some more info. My house was built in 1998. There is plenty of area for fresh air to come into the attic, but there is only one exhaust vent. I can't afford to do a ridge vent right now. I will do that when I replace my roof. Hopefully it will last another 2-3 years. The temps get really hot up there and the sensor I have also marks about 75% humidity. I don't know if thats normal but it sound high to me. I did have mold in one spot, but I cleaned it up already. Also, I sealed every hole in the attick with foam insulation. I am also going to be installing a radiant barrier and more blown in insulation. Than fan is 3.4 amps if that helps any.

nealtw 05-15-2012 01:27 PM

I haven't seen alot of fans installed here, so I have a few questions and there are lots of box vents that can be fitted into a shingled roof. How does the humidity compare with outside air. If you are puting this fan where the old vent is won't it just pull air from the same place that the vent is pulling it now.
Depending on code of coarse, you should be able to tap power from a local box, if you have a light in the attic, you might be able to run from there and put a switch inline.
Keep in mind that most homeowners that wire there own stuff, leave it looking pretty slopy, which is a red flag for home inspectors when it comes time to sell.
If you have plugged all hole comming into the attic, double check the basement or craw space and plug holes there too. A fire starting in one area of the house wants to be kept there as long as possible, to let people escape and a fan adds to the danger.

CallMeVilla 05-16-2012 07:01 PM

Couple of thoughts.

1. Do you have adequate venting along the perimeter of the roof? Many houses with blown-in insulation get those places blocked and the humidity develops mold. This even happens with batt insulation. Check your rafter line at the walls to see what is happening. If you install a fan at the only place air can escape, . . . well you can see the issue.

2. Nealw makes a great point to draw power from the attic light box. Simple, easy and accessible. Make sure you use proper box connectors, staples, and make the job neat.

Good luck with your project before Summer arrives!

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