The new owners of an estate need me to solve some electrical problems in their old wiring. Actually, most of the wiring problems seem to be in wiring that is only about 10 years old (previous owners had major renovations done to the property). Even though this is a multi-million dollar estate (and the previous owners were VERY VERY rich), the old electrical work I'm uncovering is very shoddy (which just goes to show that even when you pay a lot, you don't always get quality work). Examples of the problems I'm uncovering: white travellers not marked as hot, missing ground wires, wires breaking from fatigue due to over-stuffing a box, using un-tied (and non-adjacent) single-pole circuit breakers to feed 220VAC, badly corroded outdoor switches (behind wet location switch plates), etc. In addition to fixing problems, part of my job is to try to figure out just what some of the switches control (mystery circuits).
One problem I've found is that a lighting circuit has strange low voltages on the wires, even after the circuit breaker (subpanel in a utility room off the garage) to that branch has been shut off. It's a 3-way circuit for a hanging light in the veranda; one switch is in the living room and the other switch is in a hallway. The circuit begins in the living room where a hot 12-2 NM enters the box. The hot is spliced to the black wire of a 12-3 NM cable to the hallway box. In the hallway box, the 12-3 NM black is connected to the common terminal of a 3-way switch, and the red & white are the travelers back to the 3-way switch in the living room box. Connected to the common terminal of the living room 3-way switch is the black wire of a 12-2 NM to the fixture. When the branch is energized, the switches and light operate as expected.
If I disconnect the black wire of the 12-3 NM cable from the hot in the living room box, and I disconnect the wires from the terminals on the 3-way switches, I am still reading voltages on the individual wires of the 12-3 NM cable. This is what I'm measuring with all the wires disconnected at both ends in the living room and hallway boxes:
Branch circuit breaker #28 turned OFF
------------------------------------
12-2 NM Black wire (hot in living room box): 18.6 VAC
12-3 NM Black wire (from hot to hall common): 1.75 VAC
12-3 NM Red wire (traveler from hall switch to living room switch): 1.17 VAC
12-3 NM White wire (traveler from hall switch to living room switch): 1.28 VAC
12-2 NM Black wire (to veranda light fixture): 0 VAC
============================
Branch circuit breaker #28 turned ON
-----------------------------------
12-2 NM Black wire (hot in living room box): 122 VAC
12-3 NM Black wire (from hot to hall common): 2.1 VAC
12-3 NM Red wire (traveler from hall switch to living room switch): 1.4 VAC
12-3 NM White wire (traveler from hall switch to living room switch): 1.5 VAC
12-2 NM Black wire (to veranda light fixture): 0 VAC
============================
I measured these voltages (using a Fluke multimeter) multiple times at both ends of the wires, with the circuit breaker off and on. The voltage readings were consistant every time, so I'm confident that the readings listed above are accurate.
Another puzzler is a second 3-way switch in the same hallway box (which, by the way, is right next to a door to the veranda). That switch is fed from a circuit breaker from the main panel in the exercise room. So far, I have not been able to locate the "mating" 3-way switch for this circuit, nor have I been able to discover what this 3-way switch controls. But it too has strange voltages on it's wiring. For this switch, there is only a 12-3 NM cable entering the box with the white wire on the switch common terminal, and the red and black on the traveler terminals. Again, I disconnected all the wires from the switch terminals for the voltage measurements. This is what i found:
Branch circuit breaker #15 turned OFF
------------------------------------
12-3 NM White wire (common terminal): 0 VAC
12-3 NM Black wire (traveler terminal): 0.69 VAC
12-3 NM Red wire (traveler terminal): 0.73 VAC
============================
Branch circuit breaker #15 turned ON
------------------------------------
12-3 NM White wire (common terminal): 122 VAC
12-3 NM Black wire (traveler terminal): 38.9 VAC
12-3 NM Red wire (traveler terminal): 32.6 VAC
============================
Any ideas on any of this?
One problem I've found is that a lighting circuit has strange low voltages on the wires, even after the circuit breaker (subpanel in a utility room off the garage) to that branch has been shut off. It's a 3-way circuit for a hanging light in the veranda; one switch is in the living room and the other switch is in a hallway. The circuit begins in the living room where a hot 12-2 NM enters the box. The hot is spliced to the black wire of a 12-3 NM cable to the hallway box. In the hallway box, the 12-3 NM black is connected to the common terminal of a 3-way switch, and the red & white are the travelers back to the 3-way switch in the living room box. Connected to the common terminal of the living room 3-way switch is the black wire of a 12-2 NM to the fixture. When the branch is energized, the switches and light operate as expected.
If I disconnect the black wire of the 12-3 NM cable from the hot in the living room box, and I disconnect the wires from the terminals on the 3-way switches, I am still reading voltages on the individual wires of the 12-3 NM cable. This is what I'm measuring with all the wires disconnected at both ends in the living room and hallway boxes:
Branch circuit breaker #28 turned OFF
------------------------------------
12-2 NM Black wire (hot in living room box): 18.6 VAC
12-3 NM Black wire (from hot to hall common): 1.75 VAC
12-3 NM Red wire (traveler from hall switch to living room switch): 1.17 VAC
12-3 NM White wire (traveler from hall switch to living room switch): 1.28 VAC
12-2 NM Black wire (to veranda light fixture): 0 VAC
============================
Branch circuit breaker #28 turned ON
-----------------------------------
12-2 NM Black wire (hot in living room box): 122 VAC
12-3 NM Black wire (from hot to hall common): 2.1 VAC
12-3 NM Red wire (traveler from hall switch to living room switch): 1.4 VAC
12-3 NM White wire (traveler from hall switch to living room switch): 1.5 VAC
12-2 NM Black wire (to veranda light fixture): 0 VAC
============================
I measured these voltages (using a Fluke multimeter) multiple times at both ends of the wires, with the circuit breaker off and on. The voltage readings were consistant every time, so I'm confident that the readings listed above are accurate.
Another puzzler is a second 3-way switch in the same hallway box (which, by the way, is right next to a door to the veranda). That switch is fed from a circuit breaker from the main panel in the exercise room. So far, I have not been able to locate the "mating" 3-way switch for this circuit, nor have I been able to discover what this 3-way switch controls. But it too has strange voltages on it's wiring. For this switch, there is only a 12-3 NM cable entering the box with the white wire on the switch common terminal, and the red and black on the traveler terminals. Again, I disconnected all the wires from the switch terminals for the voltage measurements. This is what i found:
Branch circuit breaker #15 turned OFF
------------------------------------
12-3 NM White wire (common terminal): 0 VAC
12-3 NM Black wire (traveler terminal): 0.69 VAC
12-3 NM Red wire (traveler terminal): 0.73 VAC
============================
Branch circuit breaker #15 turned ON
------------------------------------
12-3 NM White wire (common terminal): 122 VAC
12-3 NM Black wire (traveler terminal): 38.9 VAC
12-3 NM Red wire (traveler terminal): 32.6 VAC
============================
Any ideas on any of this?