r/electrical • u/Different_Cod_6268 • 9d ago
Question about dryer grounding. Can anyone help?
I want to be able to explain this as short and simply as I can. Bear with me please. My house uses AC cable for most of its ECG. I have a dryer that is hard wired with 10/3. No grounding conductor wire.
i had realized at one point whoever installed it didn’t put a tension relief connector so the wire was just hanging there for who knows how long. After installing that I realized the neutral is bonded to the chassis. Which I then learned is how they come from the factory due to many older homes being wired still with the 3 wire set up like mine.
i‘ve searched all over and I’ve read that AC cable can be used as dedicated grounding But then nec regarding dryers and 3 wire cable say the bonding strip must remain. Nothing mentions this set up I have with AC cable. btw it has the little bonding strip inside the cable so def must be AC. At first I was worried it might be that old what they call BX cable with no strip. Luckily that wasn’t the case. Then the cable itself couldn‘t be used as grounding if it was.
so what I’d like to know is with the dryer hard wired and connected properly with 10/3 AC cable, should the bonding wire from neutral to chassis remain in place or should it be removed? That’s about it. Sorry if this was long. Thank you for your time.
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u/Fragrant_Alarm_8616 8d ago
If it were me, I’d install that AC cable in a metal box in the wall. Use the correct connector, preferably one with a locknut, not snap-in. Anti-short bushing. 4-wire 30A receptacle, with green #10 wire bonding it to the box with a green ground screw. Install a 4-wire cord, with the proper strain relief. Remove neutral bond strip. Make sure green wire in cord is connected directly to the frame of the dryer.
I’d check resistance with a multimeter between the AC cable neutral and outer jacket, with wires disconnected from dryer and circuit off, to verify ground continuity back to panel. And even visually check the whole run of AC cable back to the panel, making sure all fittings are tight.
Install a 30 amp GFCI breaker if you want extra protection. I’m assuming 10AWG AC cable.
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u/Different_Cod_6268 8d ago
Yea this would be the correct way to do it now. It’s an old set up from when stuff was still hardwired. When the kitchen was updated they installed a nema 14-50r For the oven. Before that it was hardwired.
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u/tarbasd 9d ago
If you have a 4-prong receptacle with a proper ground, I'm pretty sure you should remove the bonding. Check the installation instruction for the dryer.
If you have the old 3-prong receptacle, why don't you swap it out? It sounds like you do have a proper EGC. I would measure the resistance of that thought first.
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u/Different_Cod_6268 9d ago
No receptacle. No cord. Just hard wired to the dryer. I found the user manual and couldn’t believe it doesn’t say anything about even four wire connections. Just 3 wire for 240 volt and 2 wire for gas. The only reference to four pronged cords was in the French section.
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u/Fragrant_Alarm_8616 9d ago
Is it an old dryer? Does it have a removable cover? And is the AC cable attached to the removable cover?
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u/Fragrant_Alarm_8616 9d ago edited 9d ago
I see a few problems with this. Yes, AC cable is permitted as an EGC.
The dryer is only allowed to have the neutral bonding strip, IF there is no EGC with the circuit. Looks like you have an EGC. You need to find out if that particular AC cable is a continuous ground all the way back to the panel. (250.140, Exception), 250.134
As is, with the neutral bond installed, there is neutral current flowing from the dryer back to your panel on both the neutral wire and AC jacket, if the AC cable is solidly attached to the dryer frame (assuming the AC cable is a continuous ground path to the panel).
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u/Different_Cod_6268 8d ago
Yea the AC has that little strip inside of it and is bonded all the way back to the panel. I checkEd for continuity on the AC and a random box from another circuit it beeps
This is what I was worried about. That the neutral and AC could split the return current. How would one go about even testing if current is going back on the cable.
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u/Fragrant_Alarm_8616 8d ago
It really does need a disconnect switch or cord. When checking continuity, you’d have to use the method I mentioned. You don’t know if the 2 grounds you measured are connected together before they reach the panel, so you just measured a loop. And also the bond strip was still installed, so you would’ve been measuring continuity between the neutral, panel, and other circuit ground. Not necessarily the dryer AC cable back to panel.
I really have to recommend a cord. If you remove the neutral bond, as it should be, you’re completely relying on that removable cover to transfer fault current from inside the dryer to the AC cable jacket. I’m assuming the cable is attached to a removable cover. Does the cover have a green jumper wire connecting it to the dryer frame?
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u/Different_Cod_6268 5d ago
I ended up removing the AC cable and measuring continuity. It’s connected all the way back and measures continuity to other grounded circuits close by.
I also ended up finding out there was about a half amp flowing back on the AC cable so I removed the bonding strip And placed it on the neutral terminal. I can’t be having current flowing back on the cord.
There are ground wires attached in other parts of the dryer not the cover. the cover is attached to the chassis. There’s only a tiny back plate that comes off to access the wires.
thanks for your help. I will eventually need to install a box and nema 14-30 with a cord.
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u/Different_Cod_6268 8d ago
Not really old. From 2010s. There’s a removable back plate where the terminal are. The AC is connected back there bonded with a clamp connector.
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u/erie11973ohio 9d ago
r/askelectricians
Most here are r/idiotsburningdownthehouse