Crackling/sizzling noise

[TinyTool]

Hi Bodrey!

I think it is a good decision to call in an expert who can take a closer look at the wiring. Hopefully it will be a simple fix.

[Bodrey]

Hello All,

After a long break, I'm back with an update...

I never did figure out the cause of the wiring fault and I was just going to let sleeping dogs lie. However, as it turns out I needed to rip the wall open to replace the receptacle box. When the contractor renovated my bathroom in 2011 he didn't secure it properly. Over time, it has become to the point that the whole outlet moves whenever I remove any plugs. Anyway, this is a pic of the 3 sets of wires....

The cable on the far right is the "hot" wire. The other cables power the bathroom light and fan separately. The GFCI I'm using is a Leviton brand and (as expected) has both upper and lower neutral and hot terminals.

Before I replace the box and re-wire the GFCI I'd like to get some electricians' opinions on the wiring configuration. For example, should the hot and neutral be connected to the Line side terminals and the respective white and black wires of the two other cables be pig tailed and connected to the Load side? Also, which of the ground wires (if any) should be secured to the box itself (using the screw at the back of the box)? Otherwise, which one should be connected directly to the ground screw while the other two are connected to it using a pigtail? TIA

[machinist]

Welcome back Bodrey! It's good that you're taking the opportunity to properly address both issues while the wall is opened up. For your GFCI wiring configuration, here's what you'll want to do:

Since you have three cables with the far right being your line (power source), you'll want to connect this incoming hot (black) and neutral (white) to the LINE terminals of your Leviton GFCI. For the remaining two cables that power your bathroom light and fan, you'll need to pigtail the black wires together and connect them to the LOAD hot (brass) terminal, and similarly pigtail the white wires together and connect them to the LOAD neutral (silver) terminal. This configuration ensures that both your light and fan circuits are GFCI protected.

For the ground wires, the safest approach is to connect all three ground wires together using a wire nut with two pigtails - one pigtail will connect to the green ground screw on the GFCI receptacle, and the other will connect to the metal box's ground screw. This provides proper grounding for both the receptacle and the box.

Once everything is connected, make sure to secure the new box properly to prevent any movement when plugging/unplugging devices. Before closing up the wall, don't forget to test the GFCI to ensure it's working correctly by pressing the test/reset buttons. Also, it's a good idea to label the load wires for future reference.

Though I'm not a licensed electrician, just someone who enjoys DIY projects, I'd strongly recommend consulting a licensed electrician if you're not completely confident about doing this work yourself. Hope this helps!

[Bodrey]

Machinist,

I've got the GFCI wired as per your instructions. When I plug in the GFCI tester it (technically?) indicates that it's wired correctly. What I mean is, even though it's hard to tell from the pic the indicator on the far right is lit up, although it's far less bright compared to the middle indicator. I'm not sure if my tester works this way by design when testing GFCIs or if this still indicates a fault. The reason I say that is because when I press the button to test the GFCI it once again signals that the hot and neutral are reversed.

[machinist]

Hmm. It looks like the GFCI tester is giving you conflicting signals, which can be confusing. The dim indicator on the far right suggests that the tester is detecting a "correct" wiring configuration, but the difference in brightness compared to the middle light might indicate a weak or inconsistent connection. The fact that you're getting multiple indicators, especially with one being dimmer, suggests there's likely still a wiring issue. Additionally, pressing the test button triggers a "hot/neutral reverse" reading raises some concerns.

Make sure the hot (black) and neutral (white) wires are securely connected to the correct terminals on the GFCI. Hot should go to the brass screw, neutral to the silver screw, and ground to the green screw. If wires are backstabbed into the push-in connectors, try using the screw terminals instead for a more reliable connection. If this GFCI is protecting downstream outlets, ensure that the incoming power (line) is connected to the "LINE" terminals and any outgoing wiring is on the "LOAD" terminals. Swapping line and load can cause odd test results. Also, verify that the ground wire is properly secured.

If the issue persists, plug in a lamp or other simple device to see if it functions properly. If it flickers or behaves oddly, there might be a loose connection or a neutral issue. If you're comfortable with it, a multimeter can help check voltage levels between hot, neutral, and ground to confirm proper wiring.

Since the tester is initially showing "correct" but then indicating a reversal when tested, the issue might be intermittent due to a loose wire or a miswired line/load connection. Start by turning off power, carefully inspecting all wiring, and ensuring everything is securely connected.


Let me know what you find!

[Bodrey]

My particular GFCI doesn't have back stab connectors. Instead, it has something called back wire clamps. You insert the bare wire behind it and then tighten the terminal screw down to hold it in place. I tugged on the connections and they all seem to be secure. I also connected a lamp to it which worked fine - normal brightness and didn't flicker at all.

I contacted Klein to inquire whether the dim right light on their tester is by design or does in fact indicate a wiring fault. I also plan to inquire with Leviton about the wiring configuration and to ensure that the GFCI is in fact labeled properly. Perhaps the GFCI itself is faulty (unlikely but who knows).

[machinist]

The back-wire clamp system is generally reliable, but it’s good that you verified the connections. Reaching out to Klein and Leviton is a smart move.

In the meantime, if you have a multimeter, you could check the voltage between hot, neutral, and ground to see if there’s anything unusual. If everything checks out but the tester still shows conflicting results, it might be worth testing with a different GFCI tester to rule out any inconsistencies with the Klein unit. Keep me posted on what you hear from Klein and Leviton. I’d be curious to know if they provide any insight that helps clarify this.

[JimmyMechanic]

I'm wondering if something "upstream" is reversed.

To test for a hot wire versus a neutral wire, use a multimeter set to AC voltage, touch one probe to a known ground (like a metal screw on the outlet box), and then touch the other probe to each wire in question; the wire that shows a voltage reading close to the standard line voltage (usually around 120 volts) is the "hot" wire, while the wire with a near-zero voltage reading is the "neutral" wire.

Key points to remember:

• Always turn off the power at the circuit breaker before testing .
• Use a multimeter set to AC voltage .
• Touch one probe to a known ground .
• The wire with the higher voltage reading is the hot wire

I read the entire thread but might have missed, have you tested the incoming wires individually yet? Especially in older wiring black and white might be swapped. That is generally because it mattered less in (much) older installations.

Another way to test is to just use a voltage tester. They look like a pen and should only illuminate (or light up, or make a sound) when you are touching the hot wire.

Let us know!!

[Bodrey]

I tested the wiring using an analog multimeter and this is what I found:

- Voltage between the hot and neutral wires was within normal range (120V)
- Voltage between neutral and ground was near 0V as expected
- Voltage between hot and ground was only about 75V! So, there's definitely something odd going on

JM - The wiring being used appears to be the newer NMD90 standard (white sheath). However, it's easy enough to reverse the wires on the GFCI temporarily just to see if the hot/neutral reverse fault disappears using the tester.

Machinist - I plugged the tester into the GFCI above my kitchen counter and both indicator lights were equally bright. So, the issue is not with the tester - it's either the circuit or the GFCI itself.

[machinist]

The 75V reading between hot and ground is definitely a red flag. This suggests there might be a loose connection or a poor ground, which could be contributing to the flickering light and sizzling sound.

Since you've confirmed the tester is working correctly by checking your kitchen GFCI, we can narrow this down to either a ground path issue in this specific circuit or potentially a faulty GFCI unit. Before replacing another GFCI though, I'd recommend checking the ground connections at all points in this circuit - particularly at the panel and any junction boxes along the way. A compromised ground connection can create exactly the symptoms you're seeing.

If you're comfortable doing so, could you check the ground wire continuity from the GFCI box back to the panel? This might help pinpoint where the ground path is being compromised. Just be sure to have the power off when testing continuity!

Turn off the power to the circuit at the breaker panel. Double-check that power is off using your voltage tester. Then:

1. Using your analog multimeter, set it to the continuity or resistance (ohms) setting. Most meters will beep when continuity is detected, but you can also look for very low resistance readings (close to 0 ohms).
2. Connect one probe to the ground screw terminal of your GFCI box, and have someone help you connect the other probe to the ground bus bar in your electrical panel. If you get a reading of infinity or very high resistance, there's a break in the ground path.
3. If you don't want to check all the way to the panel, you can test sections at a time by checking continuity between:
   • The GFCI ground terminal and the metal box (if it's metal)
   • The ground wire at the GFCI and the ground wires in nearby junction boxes
   • Between different ground wire connections in the same box

Remember to maintain firm contact with your meter probes when testing, as even a slight movement can affect the reading. Keep in mind that a good ground connection should show very low resistance or immediate continuity.

[Bodrey]

There's a junction box located behind my bathroom sink. I'll check the connections (in particular the ground to make sure it's secure). However, I'm not able to do continuity tests between any of the wires except those located in the GFCI box itself. I'd need a tester with a separate transmitter and receiver to do that (the panel is in the basement).

However, I have another theory about the 75V reading. Let me know if you think this is a factor.

The source (hot) cable's ground wire was cut too short to wrap around the ground screw on the box and still have enough lead to be bundled with the other two ground wires. I had to use the ground wire from one of the "downstream" cables to ground the circuit to the box screw. I had to bundle the source cable's ground wire directly with the other two ground wires.

Could the fact that the source cable's ground wire isn't secured to the box explain the discrepancy in low output voltage?

[machinist]

That definitely sounds like a possible factor! If the source cable’s ground isn’t making solid contact with the box, it could create an inconsistent ground reference, which might explain the 75V reading. Ideally, all ground wires should be securely bonded together and connected to the box if it’s metal.

Since you can’t do full continuity tests, I’d say double-check that all grounds are tightly twisted together and making good contact. If you can, try adding a short pigtail to properly connect the source ground to both the box and the other grounds. That might stabilize the voltage reading.

[Bodrey]

I think I discovered the reason for the 75V reading. I opened the junction box under the vanity today. The cable that runs from the panel to the junction box is of the older black-sheathed type. It does not have a ground wire! So, I'm going to replace that run with NMD90. In case JM is right ("Especially in older wiring black and white might be swapped) this should also eliminate the hot/neutral reversed fault I'm getting with my tester.

Instead of pig tailing the source ground wire at the GFCI I'm just going to replace the cable between the junction box and the GFCI as well. That will give me plenty of lead to wrap around the box screw before bundling with the other two cables' ground wires.

I hope it all goes smoothly but like everything else around this old house it will likely turn into an ordeal. Wish me luck... 😏

[machinist]

Replacing that old cable with NMD90 should definitely clear up the missing ground issue and also help resolve the hot/neutral reversal if that’s part of the problem. Good call on running a new cable to the GFCI too. It’ll give you a clean, properly grounded setup without relying on pigtails.

And yeah, working on old wiring always has a way of turning into an unexpected adventure. Hopefully, this one goes smoothly for you, but either way, it sounds like you're tackling it the right way. Good luck! 💪🔧

[Bodrey]

DONE!!! I finished re-wiring the entire circuit and re-installed the GFCI today. Of course, I tested it before putting everything back and it's all good. It turns out that I should not have gotten any indicators lighting up when I tested the GFCI previously when pressing the GFCI button. When I tested it on my kitchen GFCIs pressing the button caused them to trip their breakers. I'm surmising that the absence of a ground wire (from the run between the panel and the junction box) meant that the tester was not able to properly test the GFCI as intended (tripping its breaker). Instead, because of a lack of ground wire, it threw a "hot/neutral reversed" fault. Problem solved - finally!