Where in the breaker box should I terminate the neutral wire from my dryer circuit?

Question

I am looking for an answer to something I am lost about, hopefully I can fins some help. I recently moved into a new home. The previous owners had a gas dryer and no outlets for an electric dryer. I had the gas line removed as it was faulty, and am now trying to install an electrical line for my electric dryer. I purchased the correct 3 wire outlet, a new 220v breaker since there was not an extra one in the breaker box, and a 15ft indoor copper building wire (which is 4 wires). I wired the cable to the outlet using the 2 hot wires (red and black) and the white wire (neutral). I left the bare copper wire (ground) out as from my understanding the dryer is already grounded and this wire is not needed. then ew breaker is installed and now i need to wire the outlet to the breaker. Here is my issue. I can run the red and black wires to the breaker, no problem, but there does not appear to be an open spot on the neutral bar, where all the other white wires are running to. There is another bar directly below it, which i assume is the ground bar that has open slots. the top bar has a large black wire running from it to the outside along with the 2 main wires coming into the house. the bottom bar has a black wire that runs to a screw a few inches away on the breaker box itself. With there being no open slots for my neutral wire to go, where should i put it?

Can I put it on the bottom bar?

Can I tie it in with another neutral wire?

Perhaps one of the other neutral wires can be moved to the other bar?

Edit: I just noticed that behind the two bars at the bottom, there is a copper piece of metal right in the center that appears to connect the 2 bars, at least I assume so.

Edit 2: Just thought I would update everyone on the situation. I added a 220V 30Amp breaker to the breaker box. I ran the red and black wires to this breaker. i then moved the green wire running to the neutral bus down to the ground bus. This green wire was labeled as upstairs kitchen with its associated breaker. I checked the kitchen equipment, it is all running normally. I then hooked the white neutral wire coming from the dryer outlet into the now open spot on the neutral bar. i then turned on the breaker and my dryer appears to be working normally as well. Thank you all for the help. I will of course be updating my dryer hookups to the 4 wire standard as soon as possible, and i will probably be adding an additional neutral bar to my breaker box as well. I will update this post if i run into any problems.

Answer 1

Without being able to see the cables as they enter the cabinet; or the ability to touch or trace them, here is what I assume is going on.

Definitions:

Grounded (neutral) from the service

A typical single split phase service is made up of 3 wires. Two ungrounded (hot) conductors, and one grounded (neutral) conductor. The ungrounded (hot) conductors will connect to the main service panel through a disconnect (usually a large breaker), while the grounded (neutral) connects to the neutral lug. The neutral lug will be bonded (electrically connected) to the neutral bus bar, and all grounded (neutral) branch circuit conductors will terminate at the neutral bus.

Grounding Electrode Conductor

This conductor is used to connect the grounding electrode (ground rod, etc.), to the grounding bus in the panel. All equipment grounding conductors will be connected to this bus.

Bonding Jumper

The bonding jumper is used to bond (electrically connect), the un-energized metal parts of the panel to the grounding system.

Assumption:

Since it appears that (what I assume is) the grounding electrode conductor terminates at the neutral bus, I'm also assuming that this is the main service disconnect. This leads me to believe that the neutral and grounding buses are bonded (electrically connected). In which case, technically, grounded (neutral) branch circuit conductors can terminate at the grounding bus.

So you have two options:

1. Terminate the grounded (neutral) from the new circuit to the grounding bus.

2. Move the green wire that is terminated on the neutral bus, to the grounding bus. Then terminate the grounded (neutral) from the new circuit, to the freed up slot on the neutral bus.

Additional Information and Code Compliance:

Number of Conductors

Since this is a new circuit, it has to be installed to current code standards.

National Electrical Code 2011

ARTICLE 250 — GROUNDING AND BONDING

VI. Equipment Grounding and Equipment Grounding Conductors

250.140 Frames of Ranges and Clothes Dryers. Frames of electric ranges, wall-mounted ovens, counter-mounted cooking units, clothes dryers, and outlet or junction boxes that are part of the circuit for these appliances shall be connected to the equipment grounding conductor in the manner specified by 250.134 or 250.138.

Which in this case means installing a NEMA 14 receptacle for the dryer, and a proper grounding conductor.

You'll have to follow the dryer manufacturers installation instructions for upgrading to a 4 wire cord. For more information see this answer, and this answer.

Since you've said that you're already using 4 wire cable, you'll simply have to terminate the grounding conductor in the cable to the grounding bus in the service panel. Then connect the other end of the grounding conductor to the grounding terminal in the dryer receptacle.

Size of Conductors

You'll also want to be sure that you're using the proper size breaker and conductors. In the case of a dryer, you'll typically use a 30 ampere breaker and 10 AWG conductors (depending on the length of the run). However, you'll want to check the dryer manufacturers installation instructions to verify this.

Answer 2

It is hard for me to tell if the two bars are physically connected from this picture and I would be surprised if they were. They should not be. The ground and neutral are connected together at the service pole, not the main panel. Why? The high voltage main line on the pole is 17,000 VAC, the secondary of the transformer on the utility pole is, for residential, 240 VAC. These voltage "potentials" are not physically connect, but magnetically connected. IN fact, the secondary can be "any" voltage potential based on other aspects of the circuit. So....the electric utility connects a ground wire to one side of the transformer to "pull" the voltage of that wire to ground potential. We have all seen a ground rod below the main panel, this is the same concept as the ground wire on the "pole".

So now we have a wire that is at ground potential (voltage) which we call the neutral. We won't get shocked by touching this wire (if we ground it correctly, otherwise, ouch).

In your picture, I see a large stranded wire on the right connected to the top bus bar which also has multiple white wires (for other circuits) connected to this same bus. I believe this large stranded wire is the ground wire coming from the pole. Then I see a black wire, screwed to the metal panel casing coming from the left, wired to the bottom bar, or bus. This is confusing, the "ground" and "neutral" should be seperate (even though they are the same at the pole).

So the answer....put all the "ground" wires on the same bus. Put all the "neutral" wires on the same bus. Then it's easy, connect your 4-wire to the associated bus bars.

If your bus bars are full, you can gang the extra wires by using a single wire "from" the bus to multiple wires connected using a wire nut (this is the same concept as putting only 1 wire on a breaker that is rated for only a single wire). Or add another bus (either ground or neutral) to the panel as needed (i.e., screw another bus next to the one that's full).

And your done!