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benepperson 08-16-2010 03:06 PM

basic switch from 4-wire?
I'm trying to wire a basic toggle switch off of a 4-wire cable with no ground. It's for a furnace shutoff switch, and I'm running into this problem because I recently just removed a few basement lights that were on the same circuit, and now I can't get it back together working again.

A nearby junction box looks like this:

So, there is a white wire and an orange wire on the left that goes to the switch, and is fed by the 4-wire cable on the right, which has a black, a white, and 2 orange wires. One of the orange wires from this power feed passes straight through to the switch (no wing nut originally), while the black/white/other orange of the power feed cable were wingnutted/spliced to some basement lights that I removed this morning.

And just for clarity's sake, this is the furnace disconnect switch, with white/orange wires coming from the left side of the junction box:

My Sperry ET6102 voltage tester shows a nice bright light when I probe from the black of the power feed to the white of the power feed, and also when I probe the spliced orange of the power feed to the white of the power feed.

I get a very dim but noticeable response when I probe from the black of the power feed to the white from the switch, and similarly from the spliced orange of the power feed to the white from the switch.

FYI, it's a 1960 house with no grounding anywhere, if that helps.

How can I properly reconnect that furnace switch?

Ranger31 08-16-2010 04:06 PM

furnace shut off switch wiring problem
didn't the teacher tell you to take notes in clase.

When ever taken on project like the one you just describe, maybe you
should had map it out, along with some photo's.

I am sure someone will come along soon have give a big hand.

But from what I read are you try to turn off this furnace with some
type of milti function thermostat?

benepperson 08-16-2010 04:47 PM

@Ranger: Yes, I realize that now, I should have taken pictures prior to disconnecting everything, but I could have sworn it was a standard all-whites-together, all-blacks together type of thing.

EDIT: At my circuit breaker, this is circuit #17 (15 amp circuit), confirmed by no current in any of these wires when I flip that breaker. My A/C is labeled on circuit #20 (30 amp circuit) and has been flipped to "on" at the breaker all day, but my A/C has never actually kicked on. I realize that it's connected to this furnace disconnect switch that I'm troubleshooting, but I don't really understand how. Maybe if I understand the connection between the two circuits, I'd have better success at solving this problem.

G17GUY 08-16-2010 05:10 PM

Is the furnace shutoff just a solenoid or what? whats made in the switch and whats it look like at the furnace?

benepperson 08-16-2010 05:54 PM

@G17GUY: The shutoff switch is just a standard toggle switch, with orange wires connected to the screws on the switch and white wires wingnutted together behind the switch. The orange and white wires that go out of that switch box run a few inches below the switch to an outlet for a humidifier. That's where I used my outlet tester to get the HOT/GROUND REVERSE I mention below.

benepperson 08-17-2010 08:01 AM

Maybe more useful information -- I used an outlet tester on the outlet that's right underneath my furnace disconnect switch (it's for an attached humidifier, and just out of sight in the above switch picture), and when I connect the black from the power feed to the white of the switch, the tester reads HOT/GROUND REVERSED. It reads the same thing when I swap in the orange from the power feed and connect that to the white of the switch. Does that help at all?

Ranger31 08-17-2010 12:41 PM

furnace shut off switch wiring problem
please answer the following question, are wires your looking at either
#14 or #12 and none are low voltage type?

The switch on the furnace, if the service man switch. This switch should
turn off all electric power inside the furnace.

If your house has a basement/cellar with stair and a door at the top, there should be another furnace switch located outside the door, but
some times their located just inside the door. This switch should also
turn off all the power turn your furnace.

Some may run the circuit for the furnace right from the electrical panel
to the switch at the top of the stairs then right the furnace service

Some may run the circuit right to the furnace install a J-Box adjacent to
the furnace, then run a 14-2/ground or 12-2/ground to switch at the
top of the stairs. This wires becomes what those in the trade would
call a switch loop circuit. The black and the white wire, (here the white
is no longer ground/neutral) but hot, 120 volts measure to ground.) make
the connection at the switch. The white insulated wire is is tape black at
both ends were it making connection. One connection is one post scres
at the switch, the other would be the black wire coming directly from
the circuit breaker.

It importanting to note, that any wireman could chose other color insuated wires, to denote the hot/120 wire to ground.

The other breaker, if its used for A.C. usually is a double-pole breaker,
and would not run to the furnace. But your furnace may be different.

Does the furnace have a electric air cleaner attach to it?

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