I recently failed my electrical inspection for something simple and want to confirm before I hook this up.


I have 200amp service to my home. I had an electrician install a 100amp circuit breaker to that panel. This is then run outside underground to a non-attached pole barn structure. At that structure is a new 100 amp panel. So I have 4 wires going into this panel. 1 is the neutral that goes to the neutral buss. 1 is ground that goes to the ground buss, which then has a copper wire attached to the buss that leads to 2 very long copper poles in the ground. The final 2 wires feed into another 100amp circuit breaker that is attached at the bottom of the panel, but it is not separated from the other circuit breakers like the main panel in my house. This feeds all the electric to the panel. I failed because the neutral bar didn't have a bonding strap to the panel itself.

So how does one determine if the panel is a sub panel or a main panel to a main panel (i.e. requires the bonding strap).

Finally, where does one get that nice S-shaped bonding strap?

 

Welcome to the forums.

A non attached structure, like your barn, requires a four wire service from your house panel to the sub panel. There should be a ground rod driven and connected to the ground buss and there should be NO bonding strap from the neutral bar to ground.

 

That is what I thought.

So, my panel has 4 wires coming in. The ground buss has a large diameter copper wire running to 2 grounding posts that are deep in the ground at the barn. So I'm good there.

I guess the question is the grounding bonding strap.

Since my neutral and ground wires are on separate busses and if you looked at this panel you would think its coming from the meter and not my house.....but power is coming from the main house.

If I put the bonding strap I would be bonding it twice....once in the house and once in the barn. That doesn't sound right. I need to find the county code that describes this so I can yell at the inspector!

 

Why are you dealing with the inspector instead of the electrician you hired? Pulling the permit and passing the inspection should be the responsibility of the licensed electrician.

That issue aside, the inspector is wrong based on National Code. A subpanel with a 4 wire feeder should not have the neutral bus bonded to the ground. You may need to file an appeal, which often goes to the inspector's boss first, then if necessary to a review board.

 

The NEC states ground and neutral can only be bonded at the first panel with an over current protection device. It is a major safety risk. Here is a thread in a professional forum that explains it. Why don't you bond the neutral at a sub panel? - Mike Holt Code Forum

NEC 2008 see 250.32(B)

 

Thanks for all the help. I did speak with my electrician who assured me he did it right. I was going by what the wife said when the inspector was here and the crappy notes the inspector left. After talking here, researching the internet, reading his notes again, and having my wife walk me through what he said and pointed at I think I misunderstood the issue.

His notes say this: Full termination on ground wire. That's basically all it says. After having my wife explain everything in detail, she said he pointed to the ground bus not the nuetral bus (as I first understood it from her description). So again I apologize.

So what it looks like now is that my negative bus does not have a green screw. It attaches to the panel just like the nuetral bus does with the plastic protectors and silver screws. My wife said the inspector said I needed a green screw behind the nuetral bus. So am I right in thinking that the panel actually needs to be grounded to the negative bus and using a green screw shows this. I'm assuming I could use the bonding strap to do this or can I just use the green screw through the plastic bus mount? BTW, its after 5pm and both the electrician and inspector are no where to be found.

 

I wondered when I was first reading your post if you didn't have a ground bar and that was the problem. From what you just wrote that is the problem. You used one of the two neutral bars as a ground bar. Panels do not normally come with a ground bar. They need to be bought and added. Best solution is buy and install a ground bar. Move all grounds to it.

If you removed the jumper between the two neutral bars replace it. If you never removed it or it can't be removed then the bar you are calling a ground bar won't work as a ground bar period. That is why it is best to just add a ground bar.

 

The green screw that bonds the neutral bar to the panel case should NOT be installed. The neutral bar should be kept "floating". The grounds, Grounding electrode conductor to the ground rods, and the ground bar, should be bonded the panel steel.

IF you can, post a picture of your panel, perhaps we can see the issue. http://www.doityourself.com/forum/li...rt-images.html

 

It could be a GE panel like in this thread... http://www.doityourself.com/forum/el...ad-center.html

 

I think you are correct that the electrician used 2 neutral bars. They were on opposite sides and were not connected together like they are in my main panel with the flat metal.

I simply ran a bare copper wire from one of the open slots in the ground bar to a green screw in the panel itself.

I'll post a picture a little later tonight.

 

What is this negative bus? There is no negative bus in an AC loadcenter. Do you mean ground bus? If the electrician is using the second neutral bus as a ground bar, it must disconnected from the first neutral bus and be bonded to the panel can with either a grounding jumper, a grounding strap or grounding screw. As far as I know, there is no requirement for the screw to be green.

Why isn't the electrician doing this? If his work didn't pass inspection it is his problem and not yours.

 

Yes, sorry for my language mistake. Too many years in the car world with pos and neg wires. I meant the ground bus.

The reason my electrician isn't doing this is because he lives about 2hrs away and I really don't need another weekend that I can't use my building because its not "certified" and he can't get out here. I've been on the phone with him about the issue and $ is going to be refunded.

So I just went to Home Depot and got a grounding bar. It screws directly to the panel and has green set screws for the ground wires (so the inspector can see green). That should solve all the issues. I'm uploading a picture here shortly.

Our inspectors here are like ****'s about the littlest things. I didn't have a "child" proof GFCI (even though its an unfinished out building) along with my trench being deep enough but them saying the wire laying on the dirt was like 1/2 inch not deep enough.....its just been one thing after another.

 

Not sure what is going on. I can't upload any pictures. I get an error message (its not just these forums so I think its a computer issue). I didn't see anywhere to upload images via my cell either because that works for other forums.

 

http://www.doityourself.com/forum/li...rt-images.html Adjust your width to 900 pixels or less and it should upload fine.

 

Not a picture size issue. Something is up with my home computer that won't allow pictures to be uploaded to any website, no matter their size. I'm uploading from another computer since I couldn't find the function on my phone screen

Well here are the before and after pictures.

Before:

As you can see the ground bar is raised with the plastic clips and nothing is attached to the panel.



After:

Now a ground bar is mounted directly to the panel.

 

Why is there a black wire on the neutral bar.

 

Its a 4 wire system (subpanel). The black/white colored wire is from the nuetral bar in the house.

 

Sure looks smaller than #4. If so not allowed by code. Wires #6 and smaller can't be remarked as neutral. They must be factory white (or gray).

Was this guy a licensed electrician? He seems to have flunked Residential 101. Can't be sure looking at the picture but he did run green for ground didn't he.That statement worries me. What you wrote seems to confirm he didn't use cable but if he used "wires", individual conductors, they should have been in conduit not laying in a trench.

 

I'm not sure about code for the wire size/color for the neutral but at no time did any inspector say that color or size was an issue and even at Home Depot, the wire is sold there as 100amp wire. I didn't get into the code for that and assumed my electrician would supply the correct 100amp wire.

Yes, green is from ground bar in the house to ground bar in the pictured panel.

I did do my own research on code for the trench and when I failed for the trench depth the inspector showed me the code book as well.... here in Warren County Ohio you are allowed to have cable (wire) buried to 24inches without conduit. In fact they prefer you don't use conduit for fear of heating the wires. If you use conduit its only 18inches in depth. What the code book doesn't say is where they measure from. I assumed it was from the depth of the hole. The inspector did from the highest point of whatever was placed in the hole (wire or conduit). For here the 100amp wire is 4 wires (may be called cable) intertwined but is easily separated. It is not enclosed in any sheathing other than the separate sheathing for each wire.


BTW, all is good. My inspector from the county stopped by today and passed me. Again, just needed to connect the ground bar to the panel, cover a hole I created in the side of the panel and switch out a GCFCI switch to a "Tamper" resistant GFCI switch. It was mainly the notes and the wifes description of the ground issue that cause confusion of what needed to be done. All you on here were helpful to confirm that I was not supposed to Bond the neutral to the case as this is sub panel to the main panel. (it just doesn't look like it because of how I wanted to turn power off in multiple places).

 

If it was URD and the white stripes is factory then the neutral is okay.

Pros, does URD have a green ground? I though it was just the undersized black that was ground.

 

I cannot guarantee this is the wire the electrician used but it looks just like the picture.

Southwire 500 ft. 2-2-4-6 Aluminum USE MHF Service Entry Electrical Cable-30163001 - The Home Depot

The Southwire Company 500 ft. 2-2-4-6 AL MHF 100 Amp Cable is designed to connect mobile homes to a supply of electricity where permanent wiring is specified by the National Electrical Code. This cable is made of 4 RHH, RHW-2 or USE-2 aluminum alloy-compacted conductors. Made of triple extruded, white-striped neutral conductor and 1 green grounding conductor helping eliminate the need for field marking
•Used as a connection between pole or pedestal-mounted equipment and a mobile home
•Used as a type USE for underground service entrance cable
•Can be used in temperatures up to 90 degrees Celsius or 194 degrees Fahrenheit
•600 Volt maximum
•500 ft. of cable
•RoHS compliant
•UL listed
•Black, cross-linked polyethylene (XLP) abrasion insulation is heat-, moisture- and sunlight-resistant
•UL listed

 

First let me say nothing wrong with your installation and it passed inspection so all is good. Just some things puzzle me but I'm not a pro so take my questions with a grain of salt.

Yes, that is what I was referring to so you can see why I'm confused by the green ground. Also very surprised he ran wire that large. Most of my questions were based on what you would normally run to a shed. Normally the feed for a shed even with a 100 amp panel would be 30 amp or 60 amp. Just curios why such a high amperage feed or do you have a smaller breaker then 100a at the main panel?

 

The wire all looks ok to me as MHF/RHW. Some jurisdictions would limit that cable to 90A, but others would allow it at 100A. In this case I don't think it's that critical either way given the low load profile in the shed.

 

Yes..I have a 100 amp cb off my main box in the house that feeds this box.

Not a shed...its for a 24*30 workshop! I wanted room to grow so instead of 60 I went 100

 

The only issue I see is that there is no main breaker retaining kit installed on the backfed main breaker.

 

You are right. I guess I could add one for safety. Not sure how likely it is for the cb to magically pop off with the door closed....but I understand the safety aspect

 

A breaker holddown or retainer is required by code for a backfed breaker.

 

Like PCboss stated, it is a code issue. My question is how did this pass inspection without the hold down kit?

 

Guess code out here says its not needed. I'll do some research to confirm that, but as of now....I had 2 inspectors and neither said anything about it being required so I doubt they are both wrong....

but they could have just overlooked it

 

From Article 408.36

(D) Back-Fed Devices. Plug-in-type overcurrent protection
devices or plug-in type main lug assemblies that are
backfed and used to terminate field-installed ungrounded
supply conductors shall be secured in place by an additional
fastener that requires other than a pull to release the
device from the mounting means on the panel.

 

If the breaker should come loose for any reason it could kill someone or start a fire or even cause an explosion.

 

I know for a fact that there are many rural areas in this country with electrical inspectors who do not know much about the NEC, but have specific points and issues they look for such as GFCI protection in kitchens and within 6 feet of any other sink, AFCI protection in bedrooms and placement of smoke detectors although placement of detectors isn't covered in the NEC. It appears the OP may be in one of those areas.