Remodeling Known Unknowns

Remodeling projects are always an adventure. In planning a project you and your contractor make assumptions about the existing condition of the building that may or may not be true. Missing an educated guess can have a big effect on a project’s profitability or throw some change orders. The classic example is the finding of hidden water damage in a bathroom remodel. The one we met this time around was in the condition of my home’s electrical wiring.

1955 Practice

My home was built for speculation by a Norfolk subdivision developer in 1955. Before me it had one owner who kept it up reasonably well and didn’t mess things up too badly. Back in the day when my home was built, 100 amp 10 circuit panels were the norm. Wiring was ROMEX 14 gage for 15 amp circuits. Center tapped 220V service to the home was common with the branch circuits divided between red and black buses with the white neutral grounded at the pole and again at the panel.

At that time it was not common to provide a ground, ground the boxes, or carry the ground to the sockets. Fortunately, the wiring has modern insulation which remains in good shape. It is possible to replace switches and sockets without cracking or loosing insulation, a common problem with rubber insulation found in the early days of home wiring.

At that time, it was not uncommon for an electrician to bring power to the fixture box, run a cable to the switch and then to the load. This results in a working switch but power remains in the box when the switch was open, and the black supply, white neutral, and the switch cable must be identified. It makes the fixture less safe and complicates the repair as the various black and white wires must be identified and reconnected correctly.

Modern Practice

Modern practice is to include a ground wire in the bundle, ground the box, and ground the chassis or body of electrical appliances using a third (or fourth) green wire connected through the plug or appliance pig tail (oven, cook top, etc). This has been code since shortly after my home was built.

The second modern practice that is significant to my project is to wire power to the switch and wire the fixture circuit from the switch. When the switch is off, the fixture box is deenergized. One or more fixture circuits violated this requirement.

Electrical Rough

The electrical contractor showed up to estimate the job, took one look at the old ungrounded wiring, and quickly realized that none of the existing circuits could be reused. This meant that the existing oven, cook top, and dryer circuits could not be reused because modern code requires four conductors: white neutral, red hot, black hot, and green ground. The cables had only three. This is a foreseeable contingency but one that could not be confirmed without some inspection.

The electrical contractor sorted everything out and realized that he could reuse one cable run by repurposing the red wire as a ground in a 120 V run for the Rennai tankless water heater. The other 220 volt circuits could not be extended to the new locations of the oven and original cooktop and the dryer would require a new circuit that included a ground. Code permits this practice provided that the wire is marked with tape or heat shrink of the proper color (green).

Electrical Safety Digression

When power is brought directly to the fixture and a switch circuit is run from the fixture to the switch location, power will be present in the fixture whether the switch is off or on. This means that the breaker must be opened to deenergize the fixture for maintenance.

Before disassembling any circuit, check the circuit with an electronic tester such as those made by Fluke. These non-contact sensors detect the electric field around the wire and will alert you to an energized circuit. The drill is

  1. Confirm that the tester works by checking a known energized cable.
  2. Test the cable to be worked on and the others in the box.
  3. Confirm that the tester still works by checking a known energized cable.

Modern testers are pretty reliable but they do have batteries that can run down mid-job. Always confirm that your tester is working reliably before and after making life safety tests of the circuits to be worked on and around.

If there is more than one circuit in a box, confirm that the others are also deenergized. It is possible for a box or device to have more than one source of power.

Mixing Legacy Work with New Work

Any new work must conform to the national electrical code in effect at the time the work is done. In a kitchen remodeling project, it is likely that old work switches will be present in the work area and may need to be moved. If the move is of some distance, for example, the wall containing the switch is removed, then a new switch will be required. Your electrician will wire this switch to current code (power to the switch then to the appliance) whether the original circuit was that way or not.

This means that the legacy fixture may need to be rewired. This is the other known unknown that is typically encountered. A properly wired legacy fixture circuit can be extended to the new switch location. An improperly wired fixture circuit must be replaced. This is the source of several change orders in my project. The other source was to add car port lights and a 220V circuit for the irrigation pump.

How things worked out

My contractor assumed the costs of replacing the unusable legacy circuits that lacked grounds.

I assumed the costs of correcting the substandard fixture circuits that were outside the work area.

I assumed the cost of moving the TV, voice, and data circuit in the wall that was removed.

I assumed the cost of adding the fixture circuits powered from the work area that were outside the work area (new carport lights).