Need help: Open Ground Problem

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  #1  
Old 10-02-04, 06:05 PM
Hammer77
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Unhappy Need help: Open Ground Problem

I have a wiring problem with which I could use some help. Here's the scoop: Sometime within the last 6 mos. the blower fan for my wood-burning fireplace stopped working. I suspected the fan itself broke, but I tested the continuity of the single-pole wall switch that controlled the fan first (it's a much easier fix!). When the switch tested out ok, I went through the hassel of removing the blower fan. Before junking the fan after removal I tested it in a near-by outlet using its now bare wire leads, and to my surprise it still worked! So, I went back to the wall switch box for more testing. After turning off the circuit breaker and removing the switch I turned the circuit breaker back on, leaving the 2 wires previously leading to the switch bare. I placed the wires across a 3-prong recepticle analyzer and it gave a reading of open ground. A neon circuit tester will light if the leads are connected to the white (neutral) wire leading to the switch and the ground wires bundled in the switch box! The tester will not light if connected to the black (hot) wire and ground, and will light very faintly if connected to the hot & neutral wires.

More info: The circuit which contains the blower fan switch also contains many standard receptacles, but no other switches. All of the receptables test as "correctly wired" using a recepticle analyzer. Nothing else on the circuit seems to be affected besides the switch/blower fan.

Anybody have any ideas on how I can fix this problem? Thanks!
 
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  #2  
Old 10-02-04, 06:30 PM
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Your testing procedure is flawed. And don't call a white wire attached to the switch a "neutral" because it is not. Because you seem to have a switch loop (only two wires in the switch box, right?), most testing at the switch box is useless.

Let's go back to the box which housed the connections of the fan itself. How many wires are in that box, what are their colors, and how was everything connected before you removed the fan?
 
  #3  
Old 10-02-04, 09:22 PM
Hammer77
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Originally Posted by John Nelson
Your testing procedure is flawed. And don't call a white wire attached to the switch a "neutral" because it is not. Because you seem to have a switch loop (only two wires in the switch box, right?), most testing at the switch box is useless.

Let's go back to the box which housed the connections of the fan itself. How many wires are in that box, what are their colors, and how was everything connected before you removed the fan?
OK, I believe my testing could be flawed, but I don't believe any electrical work was done in my house recently. One day the fan just didn't work. Doesn't a 'switch loop' suggest incorrect wiring? The fan had previously worked correctly for a period of many years.

Let me answer you questions:

1) The switch box for the fan is complicated even though it only houses the one single-pole switch. 6 wire sets are within this box! 5 of the sets are 2-wire (blk & white), and 1 is 3-wire (blk, wht, red). 1 set was connected to the switch. The Wht wire of a 2-wire set was connected to the Red wire of the 3-wire set. The black wires from these sets were connected. The Wht wire from the 3-wire set was connected to the Wht wire of the 3 remaining 2-wire sets (4 wire total). The black wires from the 3 remaining 2-wire sets were also connected (3 wires total). All 6 copper ground wires were connected.

2) The fan had a self-contained wiring box. A single 2-wire set was connected to the 2 power wires of the fan. The ground from the 2-wire set was not connected to anything.

I have probably confused the issue now. Let me know how I can clarify this for. Thanks!
 
  #4  
Old 10-03-04, 05:24 AM
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If there vis a white wire on the switch and a black wire on the switch and they come from the same cable then you do indeed have a switch loop, and you cannot test in the manner in which you did.

Please describe the wiring in the switch box more accurately, as well as the wiring at the fan. Identify all cables by numbers, and tell us exactly what the wires are connected to. We need to know which cable the wires come from and where they go.
 
  #5  
Old 10-03-04, 08:56 AM
Hammer77
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Ok, I'll try this again. However, my question remains: why would the fan just stop working 1 day if the wiring has not been changed? Also, if the switch was at the end of the circuit the white & black wires should both be connected to the switch, shouldn't they?

Better descriptions follow. Cables are numbered, wires identified by color (W-white, R-red, B-black, G-ground):

Fan: Has 1 cable leading to it from wall. The only 2 wires on the fan are connected to the cable's B & W wires inside the fan's junction box. G on the cable is not connected.

Switch box: Contains 1 single pole switch and 6 cables (4 from the bottom, 2 from the top). All cables are 2-wire except cable #3 (which is a 3-wire).

- #1B&W is connected to switch
- #2B conn. to #3B
- #2W conn. to #3R
- #3W,#4W,#5W,#6W conn.
- #4B,#5B,#6B conn.
- G wires from all 6 cables conn.

I believe that #1 is on a different circuit than #2-#6.
 
  #6  
Old 10-03-04, 06:02 PM
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If this switch truly controls the fan, and it only has two wires connected to it, and if there are only two wires at the fan, then there are additional connections somewhere. You need to find where those connections are.

Hopefully this was properly installed and those connections are in a junction box somewhere. Start looking.
 
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