Main Panel and Sub Panel Wiring Issues

amwitte1 said:

Hello everyone, I hope you are doing well.

Several years ago I purchased an older 1971 home (aluminum wiring that has since been fixed with al/cu purple connections). There is also a sizeable detached workshop (copper wiring) in the back. This workshop's wiring is in such disrepair that I switched off the sub panel power and left it off until professional help could be hired. Now that I have saved enough to start fixing the shop up, I have ran into some seemingly strange wirings, even in the main panel. I am no expert, so perhaps it isn't as strange as I think or such wiring is typical for an older home. I have provided a summary below on the most notable things I believe are issues.

1. The main service wires feed into a large double 100A breaker at the top of the column. The 60A sub panel's wires attach to the top two main lugs, meaning there is no breaker between the shop's sub panel and the main panel. This is a dangerous hazard since the wires leading to the sub panel are always live unless the entire main 100A breaker is turned off, correct? Just how bad is this? I want to upgrade the main panel, but my utility company may require the meter/panel to be moved to the front of the house (currently in back) for easy access. This would be astronomically expensive to say the least. I will be contacting the utility company to confirm.
2. There are 3 wires leading from the main panel to the subpanel (goes underground in a PVC conduit). Does this mean that there is no ground going to the sub panel? I am currently hammering in two 8 foot grounding rods next to the shop over 6 feet apart and will bury/connect them with 4 gauge bare copper wire.
3. Since the shop is detached, but planned to be insulated/drywalled/finished, does every circuit need to be GFCI? As in every first outlet should be a GFCI outlet? All outlets will be rated at 20A for power tool use. If GFCI is required, 12/2 wiring is still the appropriate size/type wire, correct?
   

I simply plan on ordering the bulk of the required materials to save money and having an electrician install/fix everything except basic outlets and fixtures. Any and all insight is welcome and thank you for taking the time to read my post!

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My suggestion would be to upgrade your service to 200 amps so you can have enough space to install a breaker for your building. Yes all detached buildings are required to be GFCI protected. You need to pull 4 wires to your building which is 2 lives, 1 neutral and 1 equipment ground. Do not drive ground rods at your building. Yes all 20 amp receptacles need to be # 12 wire. I don’t know what size wire you have going to the building but to protect your building you need to purchase a GFCI double pole breaker, which would be the protection you need. Good luck with your project and if you need anymore advice please come back

Just realized I used the wrong reply button. Please see below.

Megawatt said:

My suggestion would be to upgrade your service to 200 amps so you can have enough space to install a breaker for your building. Yes all detached buildings are required to be GFCI protected. You need to pull 4 wires to your building which is 2 lives, 1 neutral and 1 equipment ground. Do not drive ground rods at your building. Yes all 20 amp receptacles need to be # 12 wire. I don’t know what size wire you have going to the building but to protect your building you need to purchase a GFCI double pole breaker, which would be the protection you need. Good luck with your project and if you need anymore advice please come back

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Thank you for taking the time to reply Megawatt! I agree upgrading the panel is the way to go. I'm still waiting on my utility's response on whether or not it has to move. If it does, it will be out of my budget by a large margin and will have to wait. As for the fourth wire, the conduit is deep underground and travels beneath a good deal of cement. Is it possible to add a fourth wire without digging (perhaps using a strong line to drag it through)? I unfortunately have no idea how the conduit is laid out since all of this work was done before I moved in. As for the rods, they were recommended by an electrician. Will they not sufficiently ground the sub panel in place of the fourth wire?

EDIT: Researching more online, the 4th wire does appear to be required to allow the circuit to complete back to the source. Seems the electrician who recommended the rods may not be the most trustworthy if they don't solve the 4th wire problem.

I have attached pictures of both the main (bottom right 3 black wires lead to the shop) and sub panel for clarification. Both are frankly awful...

Thank you again for your time.

amwitte1 said:

Thank you for taking the time to reply Megawatt! I agree upgrading the panel is the way to go. I'm still waiting on my utility's response on whether or not it has to move. If it does, it will be out of my budget by a large margin and will have to wait. As for the fourth wire, the conduit is deep underground and travels beneath a good deal of cement. Is it possible to add a fourth wire without digging (perhaps using a strong line to drag it through)? I unfortunately have no idea how the conduit is laid out since all of this work was done before I moved in. As for the rods, they were recommended by an electrician. Will they not sufficiently ground the sub panel in place of the fourth wire?

EDIT: Researching more online, the 4th wire does appear to be required to allow the circuit to complete back to the source. Seems the electrician who recommended the rods may not be the most trustworthy if they don't solve the 4th wire problem.

I have attached pictures of both the main (bottom right 3 black wires lead to the shop) and sub panel for clarification. Both are frankly awful...
Thank you again for your time.

Click to expand...

You can install your ground wire over head if that’s possible

Megawatt said:

You can install your ground wire over head if that’s possible

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300.3 Conductors.
(B) Conductors of the Same Circuit. All conductors of the
same circuit and, where used, the grounded conductor and all
equipment grounding conductors and bonding conductors
shall be contained within the same raceway, auxiliary gutter,
cable tray, cablebus assembly, trench, cable, or cord, unless
otherwise permitted in accordance with 300.3(B)(1)through
(B)(4).

B(1) through B(4) do not apply to the installation described here.

Is this installation in the United States? What addition of which electrical code is being enforced in the jurisdiction were this property is located. If this installation is not in the United States then the following does not apply.

If this installation is in the United States it was done under a now obsolete rule which permitted the Grounding Current Carrying (Neutral) Conductor to serve as the fault current return pathway back to the source of supply in Feeders and Branch Circuits that supply a separate building. That rule was replaced with language requiring an Equipment Grounding Conductor (EGC) to be run with the other conductors of a branch circuit or feeder supplying a separate building.

You could run a set of Service Conductors from the Meter Socket's load terminals to the shop and wire it as a service. The load terminals of the meter socket would have to be listed for 2 conductors each. The usual way that is done is to change the load terminals of the meter socket from single wire terminals to 2 wire terminals with each wire having its own port. Be aware that there are single port terminals that are listed to terminate 2 conductors but they are very seldom found as the load terminals of a meter socket. The service conductors for the shop cannot pass through the house to run to the shop because service conductors may not pass through one building to reach another except under specific exceptions which do not apply to this situation.

The Service Conductors to the shop would have to have enough ampacity to carry the required load as determined by a load calculation. As long as the Service Entry Conductors remain outside the first building The Service Disconnect for the Shop could be located at the shop building. If you do run service conductors sized from a load calculation to the shop then the conductors installed in the conduit do not have to include an EGC but you would have to install the driven rod electrode you described unless there is another Grounding Electrode at the shop already such as a conductive building frame, Ground Ring, Concrete Encased Electrode...

If I read your description of the shop building feeder correctly you have 100 ampere service conductors to the house and a 60 ampere feeder tap off of that to the shop. Unless the feeder to the shop has the same conductor size as the 100 ampere Service Entry Conductors from the meter socket enclosure they do have to be protected by a Circuit Overcurrent Protective Device at their source of supply. I think it is safe to say that the tap conductors are more than 25 feet in length so you cannot treat them as Tap conductors for the purpose of having their overcurrent protection at the load end.

Tom Horne