Installation Electrical Testing Part 2-Polarity & Operational Testing

In our last post we talked about electrical continuity testing that is required in the manufactured home installation instructions. Let’s finish the discussion on installers responsibilities for electrical testing and talk about the polarity and operational tests.

Typical electrical testing requirements

First the polarity test. In general, this is a visual “check” to assure that you have properly wired items like exterior lights, ceiling fans, and hanging chandeliers. Most of these installations are pretty straightforward; black to black conductors, white to white conductors, bare ground wire to the other bare wires. But some fixtures, like hanging lights or chandeliers don’t use color coded wires. You need to know how to identify different conductors so that you connect it to the proper conductor in the junction box.

Look closely for the ribs running along the length of the cord.

If you look closely at the power supply cord to a lamp or chandelier, you will find there are ribs that run the length of one side of the cord. The conductor that has the ribs is called the “identified conductor” and should be attached to the white (neutral) conductor in the junction box.

This may be easier to see the position of the ribbing

Now, if you don’t think this is a big deal, think again. A light fixture wired with reverse polarity can present a shock hazard. The entire socket that the bulb screws into will be energized and can shock someone should they accidently touch the lightbulb base while changing bulbs or just cleaning the light fixture.

While the instructions only require a visual polarity “check”, to be certain that you have the proper polarity, it is a good idea to check the fixture with an electrical voltage meter.  Remember, the socket should not be hot (or energized)!

 Now to the Operational Tests. In simple terms, we need to assure that all the electrical equipment in the home is properly energized and can work as intended. I highly recommend that every installer have a receptacle tester like this one from Grainger. It will check for polarity, short circuits, and test the Ground Fault Circuit Interrupters (GFCI) all at the same time.

In addition to the tester, you will need light bulbs to fit every size fixture in the home. A helper to perform this test is also a good idea!


Make sure power is supplied to the home and the circuit breakers are on. Start at one end of the home and test both top and bottom of each duplex receptacle. If any receptacles are switched, make sure the switch works.  Install light bulbs and check any ceiling light fixtures, exterior lights, chandelier, etc. by operating the switches. 

In order to check GFCI’s in the home, you need to know where ground fault protection is needed.

1.       Receptacles in bathrooms even if part of a light fixture or cabinet

2.       Receptacles serving kitchen counters, including island bars. GFCI protection is not required for receptacles in dedicated spaces like refrigerator, dishwasher, disposals, etc.  See the requirement at 24 CFR 3280.806(b).

3.       Receptacles serving counters within 6’ of a wet bar sink or similar.

4.       Outdoor receptacles.

5.       The heat tape receptacle.

There can be several slave receptacles like the one seen on the left.

Keep in mind, ground fault protection can be provided from a circuit breaker in the panel box or a single GFCI receptacle which can provide protection for other receptacles, located downstream,  on the same circuit.  For example, one GFCI receptacle in the kitchen might be attached to several other receptacles along the counter. Or the one GFCI device might protect multiple bathrooms.

So, make sure any tester you purchase comes with a GFCI test button. That way you can test the receptacles and the reset button after you trip the device.

Turn on and off the bathroom and kitchen exhaust fans. Some homes have whole house ventilation fans in the laundry area. Check them too!

Next you want to test all the smoke alarms. This test is not as simple as you may think. First you need to remove all the backup batteries from each smoke alarm. Push the test button on every alarm to check 3 separate functions:

1.       Does the alarm sound when the test button is pushed?

2.       Does the alarm send a signal to sound other alarms in the home?

3.       Does the alarm sound when it receives a signal from other alarms in the home?

Typical smoke alarm testing procedures

When you are done testing each smoke alarm, make sure to replace the batteries!

The Model Manufactured Home Installation Standards (24 CFR 3285.702(f)) do not require you test water heaters, electric ranges, electric furnaces, dish washers, clothes washers or dryers, and portable appliances. But a few manufacturers require that you check to make sure electrical power is provided to this equipment or to the receptacles provided for their future installation. So, as always, check the manufacturers installation instructions that came with the home.

 If the tests are successful, document it on your Installation Checklist and keep it in your home file. If you encountered a problem, make sure you report it to the retailer or manufacturer with a record that you reported the issue. Once the problem is corrected, you should retest the affected circuit or related area in the home.  These tests are very important and must not be overlooked. As always, check the installation instructions that came with the home!


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