“Hot and ground reversed” is only one of the many diagnostic readings that can be indicated by an outlet/receptacle tester (Figure 1). It usually indicates the absence or malfunction of a neutral conductor somewhere in your system.
If you receive a Hot/Grd. Reverse reading, check your neutral conductors. One of them might be burned out, requiring replacement, or simply loose, in need of a gentle tightening.
A few different kinds of situation can trigger such a reading, however. To get a more complete picture of receptacle test results, check out the info below.
The tester is simply an instrument that reads the relationship between the hot, the neutral, and the ground wires at specific receptacles within a circuit and a miswired receptacle will not necessarily be reflected into all the other outlets within that circuit.
When the "correct" reading isn't shown by the proper lights sequence on the receptacle tester, the lights that do come on will indicate the probable cause relative to the faulty wiring, caused by broken or mixed-up wires, or wires attached to wrong terminal screws. The fault, however, might be at a different location within that circuit and some tracking could be required along the line to find its origin. While doing electrical work, there’s also the possibility that a combination of multiple faults results in misdiagnosis. The following is a progressive write-up describing every possible diagnosis and all their possible causes.
Figure 2 describes all the outlets in the following circuits, showing two outlets, each with three openings—one short slot connected to the hot terminal, one longer slot connected to the neutral terminal (providing the return path), and the semi-circular ground opening matched to the green ground terminal but also connected to the metallic enclosure box.
Figure 3 shows two circuits with the same problem but in different locations. Although the flaw is practically unnoticeable without a tester, a break (or a loose connection) in the ground wire at either location does not prevent an appliance from working when plugged into it, but it does create a serious electrocution hazard from outlets #2 in circuit A and from both receptacles in circuit B should a short circuit occur while the open ground situation exists.
An “Open Ground” reading is often the result of someone forgetting to connect the wire to the green terminal screw, or a broken ground wire, causing the following results—
1.1—A multimeter not showing any voltage between the Hot and the Ground terminals at outlet #2 of circuit A and at neither outlet in circuit B but reading 120 Volts at outlet #1 in circuit A.
1.2—The multimeter showing 120 volts between the Hot and the white Neutral connectors on all the outlets.
1.3—An outlet tester’s lights showing “Open Ground” on outlets #2 in circuit A and both outlets in circuit B, and “Correct Wiring” when plugged into Outlet #1 in circuit A.
A word of caution—A physical connection must also ground the enclosure box to the receptacle’s ground terminal.
2. Open Neutral
In Figure 4, circuit C has power in outlet #1 but none at outlet #2 nor is there any power at all in circuit D. Check for a broken or loose wire connection on one of the white leads at the specified points (inside the red star) in circuits C and D.
Testing the receptacles will result in one of the following:
2.1—No voltage showing between the Hot and the Neutral terminals in either outlets #1 or #2 of circuit D or outlet #2 of circuit C, but the multimeter would read 120 volts at outlet #1 in circuit C.
2.2—A 120 Volts reading between the Hot and the ground at any of the outlets of both circuits C and D.
2.3—A 120 Volts reading between the Hot and the Neutral at outlet # 1 of circuit C only.
2.4—The outlet tester showing an “Open Neutral” on outlets #1 in circuit D as well as in outlets #2 in both circuits C and D, and “Correct Wiring” when plugged into outlet #1 in circuit C.
Note: An appliance would work on outlet #1 in circuit C but not on any of the other outlets.
2.5—In one special case, “Open Neutral” can easily become a “Hot and Ground Reversed” as highlighted in section “5—Hot & Gnd Rev”.
3. Open Hot
With no lights on the tester at outlet #2 in circuit E or anywhere in circuit F, except for outlet #1 in circuit E that tests “Correct”, the Hot wire is open past the last outlet that lights it up—it could even be on the outfeed wire of that outlet—or before outlet #1 of circuit F (Figure 5).
4. Hot & Neutral Reversed
Figure 6 shows two circuits with an unconventional mix up of wires at some outlets. This frequently happens when adding receptacles to existing circuits, and it DOES provide voltage (although unsafe) to all the receptacles, along with the following results—
4.1—The receptacle tester will only show “Correct wiring” on outlets # 3 of circuit G and outlets # 1 & 4 of circuit H.
4.2—A multimeter will show 120 Volts across the Hot and the Neutral terminals of ALL the outlets.
4.3—A multimeter will show 120 volts between the Hot and the Gnd terminals on outlet #3 in circuit G and outlets #1 & 4 in circuit H.
4.4—The multimeter will not show any voltage between the Hot and the Gnd terminals on outlets #1 & 2 of circuit G and outlets #2 & 3 of circuit H, but 120 Volts between the Neutral and Gnd terminals making these outlets lethally hazardous by placing a live voltage on every grounded part of all appliances plugged into it.
This contradicting statement implies that the ground wire is energized with 120 volts while the hot wire is grounded, which would create a short circuit! But as illustrated in Figure 7, there are some wiring configurations that, without shorting out, can cause the receptacle tester to give a “Hot & Gnd reverse” result.
5.1—Such a situation could occur as in Figure 8, with an open neutral line upstream of the faulty receptacle (towards the panel) while a load such as a lamp was plugged into that receptacle or another receptacle downstream (farther down the line). The open line would prevent the current from flowing, keeping the light bulb from lighting. The light, therefore, can’t cause a voltage drop, but does create an interconnection between the hot and the neutral slots of the outlet energizing the two of them at 120 volts, which the receptacle tester identifies as “Hot & Ground Reverse.”
5.2—A “bootleg” ground situation is often present in older installations before safer electrical installations that included a ground wire existed. With the absence of the ground wire within the circuit, the receptacle’s ground terminal is connected to the neutral—which is a code violation. A standard receptacle tester cannot detect a Bootleg ground reporting it as correctly wired or “correct”.
The practice is unsafe and less dangerous, however than the “reverse bootleg”, where the hot and the neutral wires get mixed up ending up on the wrong terminals with the ground terminal connected to the Hot instead of the neutral wire (Figure 7) and creating the same hazard as described in section 4.4.
So armed with all this info and a receptacle tester, you’re now ready to make your home a safer place.