Electricians wanted

[doublewide]

I’ll start out by saying that I am not an electrician, do not want to teach anyone how to wire anything and don’t want to come across as sounding like I know anything about the subject.


I do want to share some of the wiring ‘mistakes’ that I have recently uncovered with the help of my electrician and I do want to get input from you all as I’ve noticed that there seems to be a lot of good knowledge here. So please, correct me as needed!


A few definitions;

Hot wire – usually black but could also be red or other colors such as when using THHN – The ungrounded conductor.

Neutral – usually white, could be grey, especially if there are multiple voltages present- The grounded conductor. Provides a neutral current return path to the source.

Ground – the earth – like, what we live on.

Grounded – attached to the earth. As the XO terminal on the utility transformer is grounded to the earth.

Ground wire – usually bare copper or aluminum but can be green as with THHN. Creates the Effective Ground Fault Path.

Bonding – Not sure how this is different than grounded, but every metal bit in a system, like work boxes, panel housings, emt pipe, motor housings, etc…, needs to be bonded together.

Circuit Breaker – Provides a means to shut off the flow of electricity in the event of an overload and or a ground fault such as the hot wire coming in contact with any grounded metal part.

Service entrance – The first circuit breaker panel on a property. Power comes from the transformer through the meter to the service entrance.


First one;

This is a sub panel in a customer’s garage. Notice that the green ground screw is still bonding the neutral buss bar to the metal housing and the ground wires and the neutrals are mixed together in the neutral buss bar. This is not correct. The only place that neutrals and grounds are to be mixed is at the service entrance. Mixing neutrals and grounds in a common neutral buss bar at a sub panel creates many parallel neutral current paths returning to the source. That’s what the electrons want to do, return to their point of origin. If there are multiple parallel paths to follow, the electrons will take all available routes, like through the cold water bond and copper plumbing, the housing, and thus the gas line to your boiler, into the earth through a ground rod, etc….. OR… through the worker who inadvertently comes between the neutrals during work on the system. Grounding, ground rods and bonding are NOT to be used for neutral current flow back to the source.

 

[doublewide]

The fix here is to install a separate ground buss bar, move all the grounds to it, and to remove the bonding screw that was bonding the neutral buss bar to the metal housing.

 

[Ct Farmer]

Not an electrician either but been doing it for 30 years and have been guided by 2 very good E1’s.

The purpose of bonding is to make a situation where there is no voltage potential between any objects. All objects are to be bonded to each other and this all leads back to one point at the ground lug in the panel.

The terms bonding and grounding are often mistakenly interchanged. Bonding is a hotly debated topic and doing it properly is a common question. A bond allows things to be at the same potential and have a path to the same ground if needed. This is why steel frame buildings are bonded. No potential if someone touches a machine and the frame. It all needs to be done right and in some unique cases not bonded, like that sub panel.

Not a fan of the cable ties in that panel. Zip ties are allowed, usually for circuit grouping as in 210.4(D), but personally I don't like the potential for hot spots.

I see a Rotophase breaker there. Generated 3-phase systems create special bonding and ground situations. Makes a difference if delta or wye system also. 3 wire floating delta creates special considerations. If 480v is created via a transformer be really careful and understand arc flash.

Do those aluminum connections have Noalox on them?

Just my 2 cents. Take it, leave it or correct me if needed.

 

[doublewide]

Ct Farmer,

I appreciate your input.

What I've heard about bonding is that it's primary purpose is to protect against lightning strike and utility failure. When there is a lightning strike, a tremendous magnetic pulse can travel through the metal parts of a structure and it's contents. Bonding these items together allows that magnetic pulse to travel from one point to another. Without proper bonding the magnetic pulse can flash between items, causing fire, personal injury or death.

Cable ties - I appreciate your point.

Noalox on all aluminum connections - YES!

Thanks again.

 

[Delmer]

Ehhh, If that box bothers you, you must not get out much.

I found an add on box from the fuse box days. It had the standard 60A fuse box, but somebody had added another box to the side with two rows of four fuses each row, no busses, all wired individually on each side of the fuse. Couldn't run two things in the kitchen, I figure it's too much on one fuse, pretty common right? There was no neutral bus in the add on box, they had run all the white wires to one fuse with the neutral feed on the other side of that fuse. Fused neutral, new one to me. Of course, it wasn't one neutral per hot, it was that one neutral for the seven hot fuses and seven circuits.

 

[Ct Farmer]

found this in a commercial freezer room at a food plant. box is a 12x12x6. Cover was hanging like that when i found it. Gotta love the globs of silicone. 240v or 480v not sure, plant had both.

 

[doublewide]

Ehhh, If that box bothers you, you must not get out much.

I found an add on box from the fuse box days. It had the standard 60A fuse box, but somebody had added another box to the side with two rows of four fuses each row, no busses, all wired individually on each side of the fuse. Couldn't run two things in the kitchen, I figure it's too much on one fuse, pretty common right? There was no neutral bus in the add on box, they had run all the white wires to one fuse with the neutral feed on the other side of that fuse. Fused neutral, new one to me. Of course, it wasn't one neutral per hot, it was that one neutral for the seven hot fuses and seven circuits.

That's interesting Delmer.... All the hots were fused... and because all the neutrals were tied together the neutral return current was too much for the fuse when more that one appliance was used and the fuse burned. Kinda confirms the point that Ct Farmer made about not zip tieing the neutrals in the panel, There can be a fair amount of neutral current and thus heat...

Thanks for the comment!

 

[doublewide]

View attachment 214806 found this in a commercial freezer room at a food plant. box is a 12x12x6. Cover was hanging like that when i found it. Gotta love the globs of silicone. 240v or 480v not sure, plant had both.

Nice!

 

[doublewide]

More definitions;

Service entrance ( I’m gonna add something to this one) – The first circuit breaker panel on a property. Two Hot Wires, one Neutral, and one ground come from the utility company’s transformer, through the meter and to the service entrance. The two hot wires are said to be opposite phases, think like sine wave. The sine waves don’t line up with each other, they are opposite to each other.

Single pole breaker – An over current protection device that has one switch on the front, one screw on the side to attach one hot wire. Output 120 volts.

Two pole breaker – An over current protection device that has one switch on the front and two screws on the side to attach two hot wires. These two hot wires will be on opposite phases. Can be used for both 120 volt and 240 volt appliances.

Multi wire branch circuit – 3 wire circuit – Edison circuit. Can be 120 volts or 240 volts. Sometimes an electrician will run a 3 wire romex ( two hot wires, one neutral and one ground) to say something like a bathroom heat-a-vent a- light. That will allow two hot wires to feed separate appliances while sharing a neutral. The advantage here is less wire to run and a reduction in neutral current. It is important to remember that the two hot wires need to be on the opposite phase to one another. In doing so the neutral amperage will cancel. So if the heater is drawing 12 amps and the fan light is drawing 5 amps, the neutral amperage will be 7 amps. If the two hot wires are improperly installed on the same phase, the neutral amperage will increase, easily to unsafe levels, in this case 17 amps. Now what if someone tied in a bathroom outlet to this same circuit and the hair drier and the fan and the heater were running?

Also, the over current protection device - circuit breaker - MUST shut off BOTH hot wires in a Multi wire branch circuit simultaneously.

Additionally, I think, and would like some confirmation on this, that the neutral current cancelling thing is how a motor can be wired with no neutral. Just two hot wires and a ground. As long as the motor is working as it should, each winding is drawing the same amps and therefore no neutral return current. Maybe?

 

[doublewide]

So here's one.. The red wire is the give away. Follow it back and find that it is part of a 3 wire romex. Both hot wires on one single pole breaker.

 

[doublewide]

The fix, rearrange the breakers and add a two pole 15 amp breaker. Transfer the two hot wires to the new 2 pole breaker.

 

[doublewide]

Here's another.. 3 wire circuit, two hots on separate breakers next to each other therefore the two hots are on opposite phases, that's good but, in a multi wire branch circuit, the over current protection device MUST turn off BOTH hot wires simultaneously, something about series circuits or something... ?

 

[doublewide]

The fix, tie the breaker together.

 

[Delmer]

I don't see anything wrong with the photo in #10, the red and black on the same screw is allowed on QO breakers, and they're not overloading the neutral because they're on the same breaker. Looks bad, and no reason to have the two wires, but I'm not sure it's illegal.

A 240 motor is no different than any other 240 load, there is no neutral required. Like a water heater, or 240 baseboard heater, the ground is connected to the frame, and the hots go to the load. If the motor is able to be connected to either 120 or 240, then you can think of it as two 120v light bulbs, wired in series for 240, or parallel for 120. For 120, one lead from each winding will be connected to neutral.

I never thought of the multiwire circuit being the logic behind the mess I described, maybe that's what somebody was thinking? For the record, NEVER fuse the neutral, OR GROUND.

 

[Steve Frazier]

Every box I've ever been in looks like your original photo with shared neutral and ground. I've never seen one with a separate ground buss. I've only worked within the county that I've lived in all my life, could this be a regional thing? Also, on 220 circuits the neutral is the ground and vice versa. At least that's how it's done around here.

 

[mitch504]

So here's one.. The red wire is the give away. Follow it back and find that it is part of a 3 wire romex. Both hot wires on one single pole breaker. View attachment 214809

But hey! It is labeled.

 

[mitch504]

Tying those breakers together like in #13, is that best practice? I've always thought that was just jerry-rigging, but, some double breakers are only connected at the handles, though, aren't they?

What if one of those breakers was a center trip, and one tripped all the way off? Do they both have to be the same model?

 

[Delmer]

The neutral and ground are connected at the SERVICE ENTRANCE only (not on any sub panel). I've never seen a ground come from the transformer, just the neutral, you supply the ground to the panel and feed it to the meter socket. Maybe that's new, and I'm out of date.

Since 94? the new four prong dryer and stove cords are required in new construction, separate neutral and ground. It's been that way for way longer for mobile homes. Other 220 loads would have no neutral, or separate neutral and ground, not shared, even though they were connected to the same terminal (must be a separate terminal now apparently, first pic has a couple shared)

 

[Willie B]

Your facts are mostly correct, and other electricians will argue with me. As you are working with AC, half the time the neutral is "hot". Current passes from the transformer, and returns to the transformer. It connects to the center of the transformer winding. It is the device we use to get half voltage. Typically in USA, 120 volts.
This center tap is grounded in one place only, in the service disconnect. It is legal to have up to 6 service disconnects, therefore, up to 6 bonding jumpers, but ALL in service disconnects.
The reason to ground the center tap is you need a point of contact in + a point of contact out to get a shock. Connecting something of the hot transformer to earth, in turn plumbing, appliances, wet concrete, and all other conductive objects people might contact, is to limit points of contact to provide shock to a person. Choosing the center tap conductor to ground limits the potential to 120 volts should a person contact on of the other transformer leads.


Breakers once only reacted to current. These days many circuits are required to have ARC FAULT CIRCUIT INTERRUPTERS. They sense arcing by recognizing ripples in the sine wave of ac power. Here, they are required in most rooms where people live.
Another type is GROUND FAULT CIRCUIT INTERRUPTER. It monitors the current balance in two, or three conductors.

 

[Willie B]

No ground upstream of the service disconnect. You can have a switch or breaker upstream from the service disconnect. It is not a service disconnect.
In example, my home has a breaker on the power pole 150 feet from my home. The service lateral supplying the house is three conductors all the way from the transformer to the service disconnect in the basement. Bonding is in the service disconnect only.
From the disconnect, to the generator transfer switch is 4 conductors, No neutral to ground bond in the transfer switch. Four conductor feeder to the main breaker panel. No bonding in the main breaker panel.
A four wire feeder supplies a sub panel in a different part of the cellar. No bonding jumper there either.
From this sub panel, a four wire underground feeder goes to the garage (detached). At the garage, there is no bonding jumper either. The ground system at garage includes the reinforcing steel in the footing, and buried ground rods.