Main Panel Replacement and Proper Grounding

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Old 08-30-16, 11:05 AM
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Main Panel Replacement and Proper Grounding

Okay so I bought a house that was built in the 1960ís and have been having electrical issues for a bit of time. I have troubleshooted the issue and found out that the breakers on the right side of the panel are not making good contact anymore. I also have multiple double and triple tapped circuits so it is time to replace the 16 slot panel with something with a few more spaces. I also will be running a new service entrance cable and keeping 100 AMP service. To give you an idea of my current setup, I have my meter and a fusible disconnect box on the outside of my house. From the disconnect box I have a service entrance cable with the two hots and a neutral running to my main panel inside the house. In the main panel the two hots run to the 100AMP breaker and the neutral goes to the neutral bar but on its way it is tied together with a ground wire which goes to a ground rod located in my crawl space (I feel like this is not how to properly ground the neutral).

Now for the new equipment I am installing a 1-1-1-3 Aluminum SER cable from the disconnect box to the main panel (about 15-20ft). From what I understand this cable is 2 hots, 1 neutral and a 3 gauge ground. If somebody can verify this for me Iíd appreciate it. Also if this cable is the right gauge for the length of the run going to a 100AMP panel?

As for the grounding situation, Since I have the disconnect box on the outside of the house and there is a ground wire in the service entrance cable, I assume I need to insert the ground into a separate bar apart from the neutral bar in the disconnect box and then connect that to a grounding rod and also the neutral bar in the disconnect box. Apologies if this is confusing, I can also draw it out. From what I have read though, I donít want to join the neutral bar and the grounding bar in my main panel since I have the disconnect box correct? Also I have included a picture of the disconnect box. If I do connect the ground in the disconnect box, do I attach it to the screw on the left of the neutral bar or do I get a completely separate bar to terminate the ground on?

Also, any tips on replacing a main service panel and running the service entrance cable would be appreciated. Iíve worked on a lot of the electrical in my house before an I know what I am doing, just want to make sure I am using the proper equipment to ground everything.

Thanks in advance and if you need any pictures or drawings of my setup let me know!


Neutral in Service Disconnect Box:
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Old 08-30-16, 06:06 PM
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"Ground" (the grounding electrode conductor) may be attached to the same assembly or bar as the neutral in the disconnect box since the latter has the first whole-house disconnecting means.

It is not unusual to have two GECs (one to a water pipe and the other to ground rod(s) and if there are not enough lugs on the neutral bus bar then you would need another bus bar, also making good contact with the metal box rear, to hold additional GECs.

While you need separate ground and neutral going downstream to the next panel, in your basement, just one conductor for both ground and neutral goes upstream up to the utility pole, usually with the two hot wires wrapped around it.

Correct, you do not want to join neutral and ground in your basement panel or anywhere else downstream. The panel might have separate neutral and ground bus bars already installed and the neutral bar may have a green screw that digs into the panel back (unscrew that) or a jumper going over to the ground bar (remove the jumper).
 
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Old 08-31-16, 06:20 AM
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Ground and neutral are connected together in main disconnect. In your new panel the are separated.

#1 aluminum is fine for 100 amps. You could actually go with #2 aluminum if it is available as #1 is rated for 110 amps based on table 310.15(B)(7) (2011)
 
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Old 08-31-16, 02:08 PM
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Tolyn Ironhand
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#1 aluminum is fine for 100 amps. You could actually go with #2 aluminum if it is available as #1 is rated for 110 amps based on table 310.15(B)(7) (2011)
It's my understanding that after the first main disconnect it's not considered a 3 wire service where 310.15(B)(7) applies. You need a 4 conductor feeder after the first main disconnect and need to use 310.15(B)(16). 310.15(B)(7) applies to the service feed from the meter base to first main disconnect. So based on my understanding #1 Al is 100A and #2 Al is 90A.

Edit: I need to correct myself after rereading 310.15(B)(7). The feeder between main disconnect and panel board is considered as being part of the main power feeder, so table 310.15(B)(7) does apply.
 
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Old 08-31-16, 04:36 PM
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Now for the new equipment I am installing a 1-1-1-3 Aluminum SER cable from the disconnect box to the main panel (about 15-20ft).
Your existing service is 55 years old. I don't have to see it to know the meter socket, disconnect and all service entrance wiring from the weatherhead on into the main panel should be replaced. The grounding needs to be brought up to today's code too. Replacing the disconnect will make it much easier to properly ground the service as it is required to terminate the grounding electrode conductors on the neutral bus at the disconnect and not to a ground bar installed inside the disconnect box.
 
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Old 09-01-16, 07:54 AM
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Yes I know it is 55 years old. I could always pull the meter and install a new wire from the meter to the disconnect box but that makes me a little uncomfortable considering there would be live wires in the meter socket. Only reason I am not replacing the disconnect box, meter box and wires to the pole is because I would have to have comed disconnect my service and for them to reconnect it I would need a permit and licensed electrician. Figured I could just upgrade my wire to the disconnect box and then have an electrician come in and replace the outside equipment.

Quick question though and I don't know if you know the answer but do you think the terminals in my current disconnect box can fit 1 gauge aluminum cable?

Mod Note: Pulling a meter is not a DIY task. It requires training and special protective equipment. If you want to see how it can go wrong, search "arc blast". Warning extremely graphic.
 

Last edited by pcboss; 09-02-16 at 04:50 PM.
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Old 09-02-16, 03:41 PM
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do you think the terminals in my current disconnect box can fit 1 gauge aluminum cable?
Maybe........if the screws aren't rusted/frozen in place. Now that you have admitted to the intention of doing this job illegally you may not get much attention.
 
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