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How to Identify Old Home Wiring Problems

How to Work with Old Electrical Wiring: Repairing Old Electrical Wiring, Old Electrical Wiring Problems.

Electrical Video #1

Generator Automatic Transfer Switch
and Electric Circuit Sub Panel

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Basic Home Electrical Wiring by Example

Identifying and Repairing Old Electrical Wiring Problems

Electrical Question: I have a 110 year old home that always has odd electrical challenges. Much of the electric has been updated or modified through the years but multiple owners have left a variety of quality to the fixes.

The current issue that has me stumped:

So this has me stumped, and these are my concerns and questions:

  1. How dangerous is it for these lights and receptacles to be sitting as a double positive element?
  2. What could have happened along the line to cause this?

I cant imagine how “out of the blue” this section of electric could end up like this. A break in the neutral, OK- I could see that. But, to end up with both lines as positive. I Need help with that one. Any ideas?

This electrical wiring question came from: Chris, a Handyman from Virginia.

Dave’s Reply:
Thanks for your electrical wiring question Chris.

Application: Repairing Old Electrical Wiring
Skill Level: Intermediate to Advanced – Best performed by a Certified Electrician or Electrical Contractor.
Tools Required: Basic Electricians Pouch Hand Tools and Voltage Tester.
Estimated Time: Depends on personal level experience and ability to work with tools.
Precaution: Identify the circuit, turn it OFF and  Tag it with a Note before working with the wiring.
Important: Burnt or damaged wiring and circuit components should be replaced with new electrical materials of the same voltage and amperage rating.
Notice: Repairs to Home Electrical Wiring should be done according to local and national electrical codes and installing new or replacement electrical parts or equipment may require a permit and inspections.

How to Work with Old Electrical Wiring

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Home electrical wiring includes 110 volt outlets and 220 volt outlets and receptacles which are common place in every home. See how wiring electrical outlets for the home are done.

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Basic Home Wiring Diagrams with Pictures

This link is helpful as a Handyman
Do-It-Yourself Electrical

The following may also be helpful for you:

Electrical Video #2

How to Wire a GFCI Outlet

without a Ground Wire

NOTE: A List of All my Helpful Videos
Will Display at the End of This Video
Keep Watching So I Can Help You Wire it Right!

Check out my YouTube Channel:
» AskTheElectrician «
and Subscribe!

Learn more about Home Electrical Wiring
with my Online Video Course:
Basic Home Electrical Wiring by Example

Dave's Guide to Home Electrical Wiring:

» You Can Avoid Costly Mistakes! «

Here's How to Do It:
Wire It Right with the help of my Illustrated Wiring Book

Great for any Home Wiring Project.
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Complete Guide to Home Electrical Wiring

Perfect for Homeowners, Students,
Handyman, Handy Women, and Electricians
Wiring GFCI Outlets
Wiring Home Electric Circuits
120 Volt and 240 Volt Outlet Circuits
Wiring Light Switches
Wiring 3-Wire and 4-Wire Electric Range
Wiring 3-Wire and 4-Wire Dryer Cord and Dryer Outlet
How to Troubleshoot and Repair Electrical Wiring
Wiring Methods for Upgrading Electrical Wiring
NEC Codes for Home Electrical Wiring
....and much more.

Be Careful and Be Safe - Never Work on Energized Circuits!
Consult your Local Building Department about Permits and Inspections for all Electric Wiring Projects.

Electrical Tips to Help You Wire it Right

The Safest Way to Test Electrical Devices and Identify Electric Wires!

The Non-Contact Electrical Tester
This is a testing tool that I have had in my personal electrical tool pouch for years, and is the first test tool I grab to help identify electrical wiring. It is a Non-contact tester that I use to easily Detect Voltage in Cables, Cords, Circuit Breakers, Lighting Fixtures, Switches, Outlets and Wires. Simply insert the end of the tester into an outlet, lamp socket, or hold the end of the tester against the wire you wish to test. Very handy and easy to use.

The Quickest Way to Check for Faulty Electrical Wiring!

The Plug-In Outlet Tester
This is the first tool I grab to troubleshoot a problem with outlet circuit wiring. This popular tester is also used by most inspectors to test for power and check the polarity of circuit wiring.
It detects probable improper wiring conditions in standard 110-125 VAC outlets Provides 6 probable wiring conditions that are quick and easy to read for ultimate efficiency Lights indicate if wiring is correct and indicator light chart is included Tests standard 3-wire outlets UL Listed Light indicates if wiring is incorrect Very handy and easy to use.

Strip Off Wire Insulation without Nicking and Damaging the Electric Wire!

The Wire Stripper and Wire Cutter
My absolute favorite wire stripping tool that I have had in my personal electrical tool pouch for years, and this is the tool I use to safely strip electrical wires.
This handy tool has multiple uses:
The wire gauges are shown on the side of the tool so you know which slot to use for stripping insulation.
The end of the tool can be used to grip and bend wire which is handy for attaching wire onto the screw terminals of switches and outlets..

The wire stripper will work on both solid and stranded wire. This tool is Very Handy and Easy to Use.

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FAQs Frequently Asked Questions and Comments

2 Responses to “How to Identify Old Home Wiring Problems”
  1. Chris Sahtterly says:

    I had a strange case last month where we had a dead short that melted piece of old BX Cable at the insulated bushing which melted right at the box clamp connector. It tested white neutral to ground downstream,where there was found burned jumpers in two boxes, not directly connected to each other, but the same circuit. I was able to pull the cut-in boxes and get unburned conductors on the existing wiring, and replaced the maxed 8/16 box with 20/40 and put all receptacles on AFCI breakers. AFCI found a mis-wired light with return from another circuit.
    This was originally discovered when the customer had plugged in a space heater, but has always used that plug for a space heater. No visual damage on the wiring to the heater plug, though it is spliced to the same circuit upstream. Could this be cumulative overload on a possible bad anti-short makeup? In the past at one of the burned receptacles they had a plasma TV for awhile, but has since been replaced with an LCD TV. So the overload condition might have occurred up to 3 years ago, and been lighter loaded ever since. Would it be worth testing all the wiring with megger? Do you have to un-wire all junction boxes before doing so, or just unplug all the equipment, TVs lamps dimmers?
    Thanks Chris

  2. Dave Rongey says:

    Hi Chris,
    Various tests can be conducted on the circuit, starting with unplugging and disconnecting all of the loads, and then checking the polarity as well as amperage on both the hot and the neutral. If there is a voltage leakage between the two that is not causing a tripped circuit then the test will show, however sometimes the leak will not show unless there is a substantial load. I recently discovered a similar situation where the metal cable clamp of an old metal box was tightened so much that it scored the neutral which arced across but did not trip the circuit. Testing with a megger will be much more accurate for detecting possible faults within the circuit wiring. As you have stated, placing the circuit on an AFCI breaker is a very good safety measure as well.
    I hope this helps,