Installing Attic Fan & Junction Box

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Old 08-02-11, 11:34 AM
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Installing Attic Fan & Junction Box

Hey, I'm installing an attic fan and first need to install a junction box in my attic. I have A light up there but no junction box. My house is really old, built around the 40's I think. I know a little about electrical but from what I understand I need to attach the junction box to the joist. and do I either make "pigtails" to the main wires from the light and fan, or just connect them into a wire nut? Here are pictures of how it currently looks:








Thanks for all the help.
 
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Old 08-02-11, 12:13 PM
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What you have there is an accident waiting to happen. It is NOT code compliant in any way, shape or form and never was. That lamp fixture is being held by ONLY the electrical wiring and THAT is simply wrong.

You have what is known as "knob and tube" wiring. Current electrical code does NOT allow any extensions on such circuits. Your only code compliant means to power the attic fan will be a new circuit run from a source that is not on a k&t circuit. Most likely that means a new circuit from the fuse or circuit breaker panel.
 
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Old 08-02-11, 12:37 PM
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Furd is correct on both points. Ungrounded circuits shouls not be extended.
 
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Old 08-02-11, 03:06 PM
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It's hanging because I unscrewed it from the joist. Am ok if I can't add to that. I know I have junction boxes in my basement. Could I connect the fan to on of those than?
 
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Old 08-02-11, 03:21 PM
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You could use a different circuit as long as it is a grounded circuit and it does not serve one of the special circuits like the kitchen, bath, laundry or a dedicated appliance. However, once you've run the new cable to the basement you might as well do it correctly and go to the breaker panel.

The light fixture is dangerous as-is because there is no box to contain the wiring -- it is right up against the framing. A spark could ignite the wood. The old knob and tube wiring is also beyond obsolete. It should be left as-is undisturbed or gutted and replaced with a modern wiring method. It is particularly dangerous on that sloped ceiling because your hand could easily touch one of the poorly insulated wires and get shocked.
 
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Old 08-02-11, 08:10 PM
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As was already mentioned, what you have cannot be extended.
In older wiring, the canopy of the light was commonly, although I dont think it was legally, used for the splices, however what I usually see in such installs is a pony cleat lampholder used, not a decorative fixture. Your best bet is to replace it with newer romex wire, with a fluorescent fixture or a porcelain lampholder.
 
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Old 08-03-11, 08:10 AM
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Just to throw in another warning, the age of your wiring may indicate that the insulation on the wires may be brittle and moving them around could cause it to flake off, resulting in more issues.

Most K&T wiring is best left untouched until it's ready for replacement.
 
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Old 08-04-11, 11:45 AM
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Ok I'm not planning on touching any of the k&t wiring now, and I went to check the junction box in my basement and it has newer wires running to the circuit breaker but also k&t wiring attached in the junction box... could I add to that if its not a dedicated circuit? and I don't think I have the option of going straight to the circuit breaker...
 
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Old 08-04-11, 12:08 PM
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That is a fuse box in your picture. There seems to be an unused 15 amp fuse on the lower left. You could run a 14-2 NM-b cable from that. If there is no open space for the neutral and ground you may have to double up a couple of ground wires. The neutral can't be doubled.

You also seem to have an unused 20a but I'd save that for future use where you need a 20a circuit.
 
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Old 08-04-11, 12:28 PM
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So I can just connect the ground to one of the grounds already going to the fuse box? and what am I suppose to do about the neutral?
 
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Old 08-04-11, 12:38 PM
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When you run the new circut, be sure to use some sort of a listed bushing. I don't see any used there.
 
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Old 08-04-11, 01:04 PM
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Originally Posted by Champion09 View Post
So I can just connect the ground to one of the grounds already going to the fuse box? and what am I suppose to do about the neutral?
Grounds and neutrals go to the bar at the bottom of the fuse panel. You can put two grounds in a hole but only one neutral per hole. There are exceptions for neutral but I don't think they aply here.
 
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Old 08-04-11, 01:09 PM
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Ok so I have two grounds going into holes, not counting the one I need to put in, is it possible to put all three into a hole that way I have an empty hole for the neutral?
 
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Old 08-04-11, 01:15 PM
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Originally Posted by Champion09 View Post
Ok so I have two grounds going into holes, not counting the one I need to put in, is it possible to put all three into a hole that way I have an empty hole for the neutral?
No, only two ground wires per hole. You could connect two grounds to a pigtail as large as the largest ground wire of the pair and run the pigtail to a hole that already has one ground. In a modern panel you would add a ground bar but I don't see a place to put it in yours.
 
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Old 08-04-11, 01:36 PM
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I can do that. So I understand, I have to find the fuses associated with the two ground wires unscrew those and the fuse I'm going to connect the new circuit to. pigtail the ground wires and put all the wires back on?
 
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Old 08-04-11, 03:42 PM
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Ray, I don't think that is a main fuse block although I could be wrong. I've never seen a panel like that.
 
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Old 08-04-11, 04:45 PM
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Originally Posted by Furd View Post
Ray, I don't think that is a main fuse block although I could be wrong. I've never seen a panel like that.
I have deleted my post. I have no real experience with fuse boxes. I should not have made that assumption.
 
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Old 08-04-11, 04:49 PM
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Originally Posted by Champion09 View Post
I can do that. So I understand, I have to find the fuses associated with the two ground wires unscrew those and the fuse I'm going to connect the new circuit to. pigtail the ground wires and put all the wires back on?
That would be safest. Be very careful there are lots of places to get shocked.
 
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Old 08-04-11, 06:39 PM
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Unless I miss my guess, that's an old Federal Pacific split bus fuse panel. The top pullout should be the lighting main.
 
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Old 08-04-11, 07:44 PM
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Unless I miss my guess, that's an old Federal Pacific split bus fuse panel. The top pullout should be the lighting main.
The buss even looks like a precursor to a stab-lok buss.
 
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Old 08-05-11, 05:22 PM
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Originally Posted by Justin Smith View Post
The buss even looks like a precursor to a stab-lok buss.
I was also looking at the attachment method of the fuse blocks and the design of the panel can edges where the cover/door attach. FPE made fuse panels similar to this for many years after the Stab Lok breaker was introduced and widely used. Their fuse panels were popular because of the versatility they offered in selecting what amperage fuse blocks you needed for each job. I still can't say for sure that it's an FPE, but sure looks like one to me.
 
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Old 08-05-11, 11:37 PM
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well I'm gonna try it next time I get a chance, I'll let you guys know how it went. and if there's somewhere on the box I can find who made it let me know where to look, if you guys are curious what it is.
 
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Old 08-06-11, 07:10 AM
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Yes, I am curious. Look at the front of the panel, inside the door and inside the box for any labels that might be there to indicate the manufacturer. Also look closely at the fuse blocks and see what the labels say on them between the center two plug fuses.
 
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Old 08-07-11, 04:44 PM
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It looks a lot like an FPE split-bus panel I replaced a bit ago. There are 2 or 3 spaces up top for 240v fuses, then a likely 60A cartridge fuse module that connects the remaining 3 spaces (currently used by 8 small circuits and one 240v larger circuit).

While there's nothing inherently unsafe about fuses and fuse panels, if you plan on continuing to do electrical upgrades, I'd certainly add a replacement breaker panel to your to-do list. If nothing else, it'll give you more spaces and a chance to clean it up!
 
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