There are times when we put forth our best effort and come up short of our goal. If it’s a personal goal, we have usually disappointed no one but ourselves. When working / playing on a team, it can be a let down for the entire group. Reminds me of the kicker from the game on Sunday. Who would want to be that guy?
It seems of late I have been inspecting quite a few modular homes. First of all I do not think they are inferior to stick built homes. In fact there are some qualities of the construction process I think are superior to site built houses.
And some I think are not.
One of these aspects is the house wiring. Since the house is built in sections or modules, the wiring has to be connected from section to section. This is accomplished by splices done using a type of locking plug. These connections are in addition to the splices made during the course of wiring up the house. Splices are weak points in any circuit and should be kept to a minimum. Knowing that these splices exist I tend to check the electrical outlets a bit more thoroughly. I do this by using my fancy tester. This tester has features I will never use, but has a few that give me very insightful information. One of these is voltage drop.
Voltage drop is what happens in a circuit when a load is applied, like when you turn on your TV or the microwave. The appliance draws current causing a drop in the voltage. The amount of voltage drop should be minimal, ideally no more than 5% according to electrical industry standards. The other parameter is the voltage associated with the drop. Ideally it should not be less than 108 volts under load.
When I tested the first outlet in the house, the drop was over 22% with a measured voltage of 93.8. I found many more outlets throughout the newer, modular structure with similar amounts of drop. A large amount of drop is indicative of high resistance in the circuit. High resistance is created at connection points.
The culprit more often than not is the connection at the outlet. Removing the cover plate I wasn’t at all surprised to see the outlets had been connected by “back stabbing”. This method is acceptable though not what would be called a best practice. Back stabbing is connecting the wires to the back of the receptacle inside a pressure type connection. The wire is inserted into a hole and is locked in place. The connection however is not as strong as one made using the screws at the sides of the outlet. Basically back stabbing is done because it is faster and easier.
What are the consequences of excessive voltage drop? Over heating wires, and with use over time potentially a fire. In addition with low voltage damage can occur to appliances.
With this amount of voltage drop in the houses wiring, I think the quality control at the factory may have dropped the ball.
James Quarello
Connecticut Home Inspector
Former SNEC-ASHI President
NRSB #8SS0022
JRV Home Inspection Services, LLC
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