Circuit Testers – an essential Tool
provided by Bob Sisson
Part of the official Standards and Practices for Home Inspections is testing a representative sample of electrical receptacles in the home to make sure they are wired safely and correctly. This isn’t something I can see directly; I need to use testing tools.
This simple tool costs about $10 and will tell me if the outlet is live, whether it is grounded, if the polarity is correct, and will test a Ground Fault Circuit Interrupter (GFCI) as well.
Hot and Neutral wires are reversed (reverse polarity)
No ground
Lights indicate the wiring is correct
Sometimes I will only get one light, which means that someone replaced a 2 wire outlet with a 3-wire and didn’t wire anything to the ground pin. This can leave 3-wire grounded appliances ungrounded, presenting a potential shock hazard.
Why is Polarity Important?
Circuits have (or should have) three wires: hot, neutral and ground. Plug something in, and the current flows out from the hot plug to whatever you plugged in, and back via the neutral wire. Until the 1950s [check date], electrical outlets had plugs with identical slots, so you had no way of knowing the polarity. Nowadays, all outlets have different-sized slots, and you can only plug things in one way.
So why is this important? Let’s take a light socket as an example. If the polarity is correct, the current flows in from the bottom of the socket, out of reach. But if the polarity is reversed, the current flows in through the socket, so if the bulb is switched off, the socket is still “hot” and it’s possible to get zapped by the current.
