Before I Flip the Breaker Tonight, I need Help

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  #1  
Old 01-16-14, 05:40 PM
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Exclamation Before I Flip the Breaker Tonight, I need Help

I took an existing power source to the air compressor and the irrigation pump of my onsite sewer system and put it underground. Believe it or not, it was strung over the roof of a carport!!

I duplicated the wiring exactly as it was, but since the existing wiring was a mess, that isn't too reassuring. I have a question on what seems to be a conflict in the wiring.

Here is the system, which is entirely separate from the house. From a 100 amp breaker at the street, power is sent through three 6-Gauge THHN/THWN underground to a breaker box that provides service to my septic system.

In this breaker box, the dark 6 guage wires each go to a 30 amp breaker. The white wire goes to a neutral bus bar. The box is grounded to earth. Leaving the breaker box is a 12-2 with ground wire to the septic controller. In the breaker, the 12-2 is wired: black to the breaker, white to the neutral bus bar, AND bare copper wire to the neutral bus bar. At the controller the black wire goes to power the pump, the white goes to the neutral bus bar BUT the bare ground goes to the Ground bus bar. So, at the breaker the Bare wire is on Neutral Bus Bar, at the controller box the Bare wire is on the Ground Bus Bar!!
 
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  #2  
Old 01-16-14, 06:03 PM
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You don't have 4 conductors from the street, so it is what it is. (I'm assuming you didn't run that #6...?) In your 30A breaker box, is the neutral bus bonded to the panel?
 
  #3  
Old 01-16-14, 06:22 PM
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I agree with Core that what you have "is what it is". Now to make it work for you safely.

From a 100 amp breaker at the street, power is sent through three 6-Gauge THHN/THWN underground to a breaker box that provides service to my septic system.
I'd start by changing the breaker at the street to 30 amps.

The box is grounded to earth
A #6 GEC to a ground rod? Is the neutral bar bonded to the box?
 
  #4  
Old 01-16-14, 06:53 PM
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No, I didn't run the three #6s from the street. And I don't want to mess with the street, as that 100 amp box (single breaker) also powers the house.

The neutral bus is isolated in the breaker box that has the two 30 amp breakers. I guess I am just having confusion over the idea that one end of the #12 is attached to a neutral bus bar (isolated) and the other end is attached to a ground bus bar in the septic tank control panel, and not to the neutral bus bar in that panel.

I guess I'll flip the switch and see what happens.

One last thing, That 100 amp breaker probably hasn't been tripped in years. When I flipped power back on at the street there was a one second long quite sound that was like a sizzle! Was that probably just the result of corrosion on the contacts in the breaker?
 
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Old 01-16-14, 07:00 PM
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The neutral bus is isolated in the breaker box that has the two 30 amp breakers.
This is incorrect. It needs to be bonded if you're going to roll with what you have. You were right to be confused.

You didn't say anything about CasualJoe's ground rod query.
 
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Old 01-16-14, 07:06 PM
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Here is the system, which is entirely separate from the house. From a 100 amp breaker at the street, power is sent through three 6-Gauge THHN/THWN underground to a breaker box that provides service to my septic system.
I don't want to mess with the street, as that 100 amp box (single breaker) also powers the house.
It sounds like the power for your septic system is not separate from the power for your house. In fact, it sounds like it's double-tapped off the main overcurrent protection device for the subpanel in your house.

It sounds like this setup needs to be reworked to feed each separately.

Alternatively, the power for the septic system should be fed from the subpanel in the house. It should not be tied into the breaker which is protecting the system in the house.
 
  #7  
Old 01-16-14, 07:13 PM
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OK, I'll make the neutral bonded at the service panel and otherwise leave things as is, for now.
The service panel has a screw in the box/housing with the grounding wire running to a grounding rod driven all the way into the earth.
 
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Old 01-16-14, 07:19 PM
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The neutrals and grounds should be bonded together and to one or more low-impedance parths to earth at the location of the first overcurrent protection device in the system. For your system that's the box at the street with the 100A breaker in it.

The neutrals must be isolated from ground everywhere else in the system.
 
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Old 01-16-14, 07:24 PM
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Nashkat, the OP's setup is standard operating procedure for the power company out here in the boonies where I live. The 100A breaker could have been added at a later date. I'm not saying it's "right". But if you add a breaker where none existed before (and where things were legit before), now you have to tear up everything that's already run to your buildings?
 
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Old 01-16-14, 07:26 PM
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Thanks! I think I get there by moving the bare copper wire in the septic tank control panel from the Ground bus to the Neutral bus bar. Then it matches the wiring in the 30 amp service panel.

Wow, I wish that decades ago when this was wired they had used a four conductor feed to the subpanel. I think I could have follwed that.

Yep, I am in the boonies too.

THANKS AGAIN.
 
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Old 01-16-14, 07:30 PM
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Thanks! I think I get there by moving the bare copper wire in the septic tank control panel from the Ground bus to the Neutral bus bar. Then it matches the wiring in the 30 amp service panel.
NO. Do NOT do this. I don't know if this was supposed to be a joke or not. Do not move anything in the septic tank control panel. The neutral must be isolated there.
 
  #12  
Old 01-16-14, 07:59 PM
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A 3 wire feeder used to be allowed as long as there was no metallic path between the two buildings. The second panel was again bonded like the service panel.
 
  #13  
Old 01-16-14, 09:27 PM
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OK Core. Thanks for catching me on that. I think "it is what it is" for now, and I'll have an expert give things a once over look in the morning to make certain he agrees.

Thanks to all for quick advice.
 
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Old 01-17-14, 08:17 AM
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I'd start by changing the breaker at the street to 30 amps.
I didn't catch my typo till this morning, I had meant to say you should change the breaker at the street to 60 amps, but you say the 100 amp breaker also feeds the house so you cannot do this. Hope I didn't create confusion over my typo.

Regardless, if the #6s are double lugged with the 100 amp feeder to the house, you still have a problem that must be corrected.

It sounds like the power for your septic system is not separate from the power for your house. In fact, it sounds like it's double-tapped off the main overcurrent protection device for the subpanel in your house.
Exactly how are the #6s connected to the 100 amp breaker? Assuming they are double lugged in the 100 amp breaker, you could use the "Outside feeder tap rule of unlimited length rule [240.21(B)(5)]" after the tap is corrected. Read more on tap rules here. The Outside Feeder Tap Rule is listed last with an illustration by Mike Holt.

Understanding the Rules for Feeder Taps | Code Basics content from Electrical Construction & Maintenance (EC&M) Magazine

The Outside Feeder Tap Rule should work for you, but the #6s will have to tap the 100 amp feeder after the 100 amp feeder leaves the 100 amp breaker, the #6s cannot be double lugged to the 100 amp breaker.

Now, you stated the neutral at your main service panel in the house was bonded to ground and you have the required ground rod and GEC. What about the 30 amp service panel? The neutral in the 30 amp panel must also be bonded to ground and have both a ground rod and #6 GEC.

Do not move anything in the septic tank control panel. The neutral must be isolated there.
Core is right. AFTER the 30 amp service panel, the neutral and ground must be isolated. The same applys to AFTER the 100 amp main service panel in the house.
 
  #15  
Old 01-18-14, 12:37 PM
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Originally Posted by CasualJoe
Core is right. AFTER the 30 amp service panel, the neutral and ground must be isolated. The same applys to AFTER the 100 amp main service panel in the house.
Maybe I'm missing something about the OP's setup, But I don't see why there should be any neutral bonding after the 100A MOPD location.

Originally Posted by Core
But if you add a breaker where none existed before (and where things were legit before), now you have to tear up everything that's already run to your buildings?
No, I don't think you'd have to do that. It seems to me that removing a bonding screw or jumper here and there, and maybe adding a bonded ground bar or two, would be all that's needed.

If a new service disconnect is added ahead of an existing GEC bond, thereby placing the older bond in a subpanel, how is the system effectively protected against high-energy transients until the older bond is removed?
 
  #16  
Old 01-18-14, 05:19 PM
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Maybe I'm missing something about the OP's setup, But I don't see why there should be any neutral bonding after the 100A MOPD location.
Nash, the way I understand it, the OP has a 3 wire feeder to a 30 amp backfed main breaker panel. The septic control panel is fed from the 30 amp service panel.

core
Nashkat, the OP's setup is standard operating procedure for the power company out here in the boonies where I live. The 100A breaker could have been added at a later date. I'm not saying it's "right". But if you add a breaker where none existed before (and where things were legit before), now you have to tear up everything that's already run to your buildings?
Just trying to make the best of what the OP has.
 
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