[generalts0]

Hi all,

I'm installing a 30a 2-pole breaker in my breaker panel to be a dedicated line for a clothes dryer. The panel is Square D type QO with 100a main breaker and 20 breaker slots.

Clothes dryer manual says to use 10-3 cable, make sure to connect that 4th wire to the ground bar, or use 10-2 with a grounding strap and clamp that to a grounded object.

Home depot expert says the ground bar in the breaker panel is the metal bar with a cable bolted to it that terminates into the water main.

I used 10-3 and now have the black and red wires connected to the 2-pole breaker, and the white wire connected to the neutral bar where all the other white wires in there are connected.

The skinny, uninsulated (aluminum?) 4th wire from the 10-3 is connected to what the breaker panel sticker says is the ground bar and which is bolted to a big cable that is clamped to the water main at the other end like Mr. Home Depot said.

The thing is, the ground bar and the neutral bar, as far as I can see, are bolted together -- and are clearly designed to be based on how they're shaped. Unless there's some hidden insulation between them, it seems the neutral bar is grounded, and the grounding bar is... really another neutral bar?

I don't see anywhere in the panel (30 years old at least) to connect an additional grounding bar (no screw holes implying 'ground bar goes here'). The manufacturer's sticker in the breaker door says which one of those two bars is the neutral and the other which is the "ground if nec". Mr. Home Depot said I should assume electricians ignore all breaker panel stickers and just follow the grounding cable.

If I connect the 4th wire to the existing grounding cable or even run a new wire to the water main pipe, it seems logical to me that it will still be connected to the connected grounding and neutral bars.

An electrician told me off the record that everything is grounded anyway because a neutral wire is also a grounding wire, the usefulness of a dedicated grounding line is a myth, so just make sure your hots and neutrals are wired correctly at the breaker and the grounding wire won't make a difference, even if it's disconnected.

So kindly help me with this: do I need to rewire something -- either this circuit, this 4th wire, the whole panel, the neutral bar, should I not worry about it, etc... thank you for any advice you can give.

[stanfortyman]

WOW! Some very scary information here that you have received.

First off, there are NO "experts" at home depot. You may get someone from time to time who has a clue, but it is doubtful any of them are even close to experts.



Next, these instructions are downright dangerous!

Clothes dryer manual says to use 10-3 cable, make sure to connect that 4th wire to the ground bar, or use 10-2 with a grounding strap and clamp that to a grounded object.

10/2 was NEVER allowed to be used to feed a 120/240v dryer circuit. An insulated neutral was always required with one exception, which was type SE cable. Even if an ungrounded 3-wire circuit was run they fail to describe what a legal and safe "grounded object" is.

I used 10-3 and now have the black and red wires connected to the 2-pole breaker, and the white wire connected to the neutral bar where all the other white wires in there are connected.

The skinny, uninsulated (aluminum?) 4th wire from the 10-3 is connected to what the breaker panel sticker says is the ground bar and which is bolted to a big cable that is clamped to the water main at the other end like Mr. Home Depot said.

Mr. Home Depot's description is ambiguous at best. The ground bar and neutral bar in a MAIN panel are the same bar(s).
The fact that the water bond/ground goes to these bars in the MAIN panel is irrelevant in this case since for the most part it has nothing to do with "grounding" your panel with regard to breakers tripping and short circuits.
The ground wire goes to the same bar as the neutral in your main panel. This is NOT to say that the ground and neutral serve the same purpose.

Why do you describe the ground in your 10/3 as thin and aluminum? It should be copper and the same size as the other wires. Did you just run this cable? Or was it old?

An electrician told me off the record that everything is grounded anyway because a neutral wire is also a grounding wire, the usefulness of a dedicated grounding line is a myth, so just make sure your hots and neutrals are wired correctly at the breaker and the grounding wire won't make a difference, even if it's disconnected.

THIS is the scariest part of all. This guy is NUTS!
He really needs to get back in the books and re-learn what he thinks he knows!
The ONLY thing he was close to right about is that in OLD dryer and range circuits the neutral could also serve as the ground. This DOES NOT apply to any other branch circuits, and is dangerous advice to be giving to a lay person. This was also removed from the code many years ago. A dedicated ground wire has been required since this long ago change.

[Tev]

Neutral is intended to carry current, the grounding conductor only carries current if there is a fault. Yes, neutral and grounding are connected at the main disconnect but they serve different purposes.

Think of it this way, if in your dryer one of the hots comes loose and gets in contact with the metal frame you basically have a very large live conductor waiting to zap the next person to touch. That is unless you have a grounding wire, the grounding wire allows the current to flow if a fault like this happens and with little resistance the amperage will be high enough to trip the breaker.

In short, a circuits work without grounding conductors but it is necessary to have them because people get killed without them. A neutral has nothing to do with safety and a lot to do with making the circuit work.

[generalts0]

Thank you stanfortyman and Tev, I really appreciate your input, and read your replies on Saturday though I couldn't respond until now.

I bought and installed what was labeled 10-3 bx cable, it has three rubber-insulated copper wires and one apparently uninsulated white metal wire.

Long story short, I thank you for bringing to my attention the questionable authority of the electrician's advice on grounding.

Thanks also for noting that the ground wire goes to the same bar as the neutral in your main panel. That point was what I found most confusing.

Also I took a look at the schematic of the dryer and too your comments and put it all together, now I understand how/why the grounding line works (essentially, it seems one could ground any potentially hot appliance by attaching a conducting wire to its casing and to a ground bar).

BTW, I went to another hardware store and their 10-3 cable, a different brand than the Home D one, had the same skinny uninsulated fourth wire as the one I purchased.

Many thanks,
The General