Rewiring 100 amp panel

[ckucia]

PO of our house left a little to be desired in his installations. I'm trying to fix a few things and would like to get confirmation that I'm on the right track. We don't have code inspections here in this part of WV so I'm on my own.

Our house has underground service. The transformer is probably 200' away from the house. Meter is on the side of the house. So far so good.

From the meter, there is a 2" conduit running to a disconnect service box with 200a breaker. Aluminum wire connects them. Not sure what size, but about as large as my fingers.

So problem #1. The disconnect has space for additional load breakers. There's an opening where one presumably used to be. For whatever reason, the PO didn't use that. On the lugs off the main breaker, there is similarly large aluminum wire to the feed going to the house. And then the PO added copper wire (looks like 2awg) by opening the lugs for the house, slipping the copper on top of the aluminum wire, and tightening the lugs. This seems like a very bad idea to me and since I discovered it, I'm not using any heavy loads in the garage - just a few light bulbs when I absolutely have to. I now have a 100a breaker that fits the disconnect and plan on moving the garage feed to it this weekend. We have electric heat which makes this an even worse problem IMHO.

Problem #2. There's only one ground wire leaving the disconnect. It's aluminum, and maybe #14 (really). It's not connected to a ground rod, and I don't see a rod anywhere. I don't know where it used to go, but I know it's not doing anything now. I've never had a house with underground service, but it seems like I oughta have a ground rod here if not two and some more substantial cable running to it from the disconnect.

Problem #3. The fuse panel in the garage is right above where the water from the pumps (well and cistern) exit out of the slab and where the pressure tank is. If there was ever a problem with a hose splitting, I'd be soaked with water as I attempted to shut off the power in the fuse panel which would also be sprayed with water. This seems like a very bad idea to me.

My water line from the garage to the house isn't buried deep enough (it froze last winter when we moved in). So I'm about to dig a trench and sink a deeper line anyhow. So it seems like a good time to redo the wiring between the garage and the house. If I move the fuse panel about 8' over, it won't be close to the water anymore and will involve very little rewiring of the garage (only one circuit would be too short - the rest I can just shorten).

So my questions...

New feed to the garage will have to be about 8' longer than the existing so I need new wire. I figure 30' total for each line being generous. Would 2AWG copper be sufficient for 100amp service? Can I run 3 THHN 2AWG lines for the hots and neutral and a 4awg ground? I already have the 100a breakers on both sides and can reuse a lot of the 2" conduit.

In the garage I'm running a well pump for a 100' drilled well, and a cistern pump about 50' below grade (I think it's a 3hp). Plus I have a small compressor (hoping to get a 5hp some day), 100a welder (hoping for a larger one eventually), various power tools, etc. I'd rather over-spec the wire and not use it than underspec it and have to replace it someday.

I'm open to aluminum, but it seems like the price difference at this distance wouldn't be worth the extra PITA of the larger wire thickness.

Grounding. Do I need one or two ground rods at the house? How far from the panels and what sort of wire should I run to them? How about at the garage 9' away - does it need it's own ground rod or rods?

We have clay soil which stays damp pretty much the whole year as the house is about half way down a hill.

Should the ground and neutral be bonded at the disconnect where I'm feeding the garage and house? (They are now) How about at the panel inside the garage? (They are now).

Any other considerations I'm missing?

I'm going to bounce the whole project off my facilities manager at work to get his input, but this place is such a great resource, I figured the more minds the better...

Believe it or not, this all passed the home inspection last December prior to us buying the place.

 

[Norcal]

"
Believe it or not, this all passed the home inspection last December prior to us buying the place."

Lot of home inspections are not even worth using as toilet paper.

 

[wyliesdiesels]

PO of our house left a little to be desired in his installations. I'm trying to fix a few things and would like to get confirmation that I'm on the right track. We don't have code inspections here in this part of WV so I'm on my own.

Our house has underground service. The transformer is probably 200' away from the house. Meter is on the side of the house. So far so good.

From the meter, there is a 2" conduit running to a disconnect service box with 200a breaker. Aluminum wire connects them. Not sure what size, but about as large as my fingers.

So problem #1. The disconnect has space for additional load breakers. There's an opening where one presumably used to be. For whatever reason, the PO didn't use that. On the lugs off the main breaker, there is similarly large aluminum wire to the feed going to the house. And then the PO added copper wire (looks like 2awg) by opening the lugs for the house, slipping the copper on top of the aluminum wire, and tightening the lugs. This seems like a very bad idea to me and since I discovered it, I'm not using any heavy loads in the garage - just a few light bulbs when I absolutely have to. I now have a 100a breaker that fits the disconnect and plan on moving the garage feed to it this weekend. We have electric heat which makes this an even worse problem IMHO.

yeah thats not kosher. definitely fix that. good catch.

Problem #2. There's only one ground wire leaving the disconnect. It's aluminum, and maybe #14 (really). It's not connected to a ground rod, and I don't see a rod anywhere. I don't know where it used to go, but I know it's not doing anything now. I've never had a house with underground service, but it seems like I oughta have a ground rod here if not two and some more substantial cable running to it from the disconnect.

you should have at least one existing grounding electrode. since you have none, put 2 in spaced 6' apart since thats current code. Connect them with solid bare #6 copper.

Also should make sure any metal water and gas lines are bonded to neutral bar in disconnect to prevent them from becoming energized.

Problem #3. The fuse panel in the garage is right above where the water from the pumps (well and cistern) exit out of the slab and where the pressure tank is. If there was ever a problem with a hose splitting, I'd be soaked with water as I attempted to shut off the power in the fuse panel which would also be sprayed with water. This seems like a very bad idea to me.

My water line from the garage to the house isn't buried deep enough (it froze last winter when we moved in). So I'm about to dig a trench and sink a deeper line anyhow. So it seems like a good time to redo the wiring between the garage and the house. If I move the fuse panel about 8' over, it won't be close to the water anymore and will involve very little rewiring of the garage (only one circuit would be too short - the rest I can just shorten).

So my questions...

New feed to the garage will have to be about 8' longer than the existing so I need new wire. I figure 30' total for each line being generous. Would 2AWG copper be sufficient for 100amp service? Can I run 3 THHN 2AWG lines for the hots and neutral and a 4awg ground? I already have the 100a breakers on both sides and can reuse a lot of the 2" conduit.

In the garage I'm running a well pump for a 100' drilled well, and a cistern pump about 50' below grade (I think it's a 3hp). Plus I have a small compressor (hoping to get a 5hp some day), 100a welder (hoping for a larger one eventually), various power tools, etc. I'd rather over-spec the wire and not use it than underspec it and have to replace it someday.

I'm open to aluminum, but it seems like the price difference at this distance wouldn't be worth the extra PITA of the larger wire thickness.

so the total run panel to panel is 30a? If so then #2 copper is oversized for 100a. For copper you need #3. Or #1 if aluminum. The EGC/ground wire can be #8 cu or #6 al.

The loads you list sounds like a 90a branch feeder would suit you well and thus i would use @2 al MHF. It can be direct buried but must in conduit indoors. Conduit panel to panel is recommended.

The difference between #3 cu and #2 al, in wire size, is not much at all.

Grounding. Do I need one or two ground rods at the house? How far from the panels and what sort of wire should I run to them? How about at the garage 9' away - does it need it's own ground rod or rods?

We have clay soil which stays damp pretty much the whole year as the house is about half way down a hill.

Every detached structure needs 2 ground rods if going by current code. So wherever the disconnect for the service is(at the house??), needs 2 rods, and the garage will need 2 rods.

Should the ground and neutral be bonded at the disconnect where I'm feeding the garage and house? (They are now) How about at the panel inside the garage? (They are now).

The only place neutral should be bonded is at the first means of disconnect for the service. In your case, what youre calling the disconnect.

Any subpanels within the same structure as the main service should have isolated/unbonded neutrals. This includes the branch circuit panel for the house circuits.

Now as far as the garage codes, code prior to 2008 allowed bonded neutrals as long as there was no parallel metallic pathways that neutral return current could flow on.

So thats why your current garage panel is bonded.

Having said that, since you are running a new 4-wire feeder(is the current feeder 3-wire?), the panel should be switched to isolated/unbonded neutral.

It also sounds like you may have metal water lines and thus the garage panel shouldve never been bonded.

And unbonding the garage panel will probably require adding a ground bar kit. You called this a fuse panel and if it IS TRULY a fuse panel, then i would replace it with a new breaker panel. This will require a separate ground bar kit as well.

The GEC from the new rods will connect to the new ground bar you put in.

Any other considerations I'm missing?

I'm going to bounce the whole project off my facilities manager at work to get his input, but this place is such a great resource, I figured the more minds the better...

Believe it or not, this all passed the home inspection last December prior to us buying the place.

Im sure there will be lots more to discuss. But i would stick with the above for now as that is quite a bit of stuff to meddle over for now.

And sadly many home inspectors arent worth the inspection paper they type on. Many dont know much about electrical....

 

[ckucia]

Thanks WyliesDiesels. Everything makes sense to me.

All my water lines are various plastics. I have 100lb propane tanks for the stove and dryer - all the other utilities are electric, although we're considering having a permanent propane tank installed with hard lines so I'll keep the bonding in mind.

Hadn't occurred to me to check the house panel to see that its neutral is unbonded. Thanks.

Feed to the garage is currently four lines but that ground doesn't go anywhere other than maybe all the way back to the transformer.

I meant to say breaker panel. Our houses all had fuses when I was growing up and sometimes it slips out.


Here's a question. Do the grounding electrodes need to be outside the structure? Was thinking that inside the garage, through or under the slab along the wall where the panel box will be might make more sense for the garage electrodes. Less chance of an implement or mower catching them when I run the tractor between the structures.

 

[Zeke]

Thanks WyliesDiesels. Everything makes sense to me.

All my water lines are various plastics. I have 100lb propane tanks for the stove and dryer - all the other utilities are electric, although we're considering having a permanent propane tank installed with hard lines so I'll keep the bonding in mind.

Hadn't occurred to me to check the house panel to see that its neutral is unbonded. Thanks.

Feed to the garage is currently four lines but that ground doesn't go anywhere other than maybe all the way back to the transformer.

I meant to say breaker panel. Our houses all had fuses when I was growing up and sometimes it slips out.


Here's a question. Do the grounding electrodes need to be outside the structure? Was thinking that inside the garage, through or under the slab along the wall where the panel box will be might make more sense for the garage electrodes. Less chance of an implement or mower catching them when I run the tractor between the structures.

How do you propose to place the ground rods through the slab? They have to go into the earth no less than 45º if at grade, and you need 8 feet minimum contact with soil. You can have the rods inside but they can't be covered up and you need 10' rods to have the top accessible. If you drywall (or otherwise cover the wall where the rods might be), you need an access panel to see the connection.

Also, you can bury the top of the rod outside so that it's not a hazard. Use a clamp rated for burial and drive the rod 4" below the surface. Run your copper so that it is protected. Don't place a concrete walkway over the buried rod and connection unless you leave a well.

 

[ckucia]

I was thinking of busting a hole in the slab near the wall, driving the rod into the ground, burying it after the conductor was attached and pouring concrete over it with the line sticking out. I'd never heard of this being done before, which is why I posted the question.

I knew the rods could be driven below grade with the wires shallow buried to protect them. Was thinking that being below the slab would protect them even more. A couple inches isn't much if the bush hog inadvertently drags along the ground moving past those wires. Stuff happens. With 9 foot between the structures, there's not a whole lot of extra room and with the meter box on the house side, I'd be inclined to have the tractor closer to the garage rather than risk clipping the 200amp service entrance. That puts me closer to the two grounding rods I'd be putting in for the garage.

 

[Zeke]

Here's a thought: drill down through the bottom plate of your framed wall into the footing and at an angle towards the exterior. Drill the concrete at an angle so that the rod enters the soil right at the grade line and drive a 10 footer almost to the top of the plate getting your 8'. Depending on the height of your stem wall, the concrete drilling could be a matter of less than a foot and keep the rod out of your way for cleaning, etc. If not, go back to the first idea.

Having the rod(s) out in the soil exposed to rain ensures that the deep soil will be moist 24/7/365.

You can bury horizontally but the trench has to be rather deep. 30" min I believe before you can start adding up how many feet are in the soil. Now you're looking at a really long rod.

I don't know how crazy you are with the bush hog but maybe you have to do some hand work in some areas.

 

[nsula_country]

I was thinking of busting a hole in the slab near the wall, driving the rod into the ground, burying it after the conductor was attached and pouring concrete over it with the line sticking out. I'd never heard of this being done before, which is why I posted the question.

I knew the rods could be driven below grade with the wires shallow buried to protect them. Was thinking that being below the slab would protect them even more. A couple inches isn't much if the bush hog inadvertently drags along the ground moving past those wires. Stuff happens. With 9 foot between the structures, there's not a whole lot of extra room and with the meter box on the house side, I'd be inclined to have the tractor closer to the garage rather than risk clipping the 200amp service entrance. That puts me closer to the two grounding rods I'd be putting in for the garage.

It would be easier to use a hammer drill to drill a hole in slab for ground rod to go through.

CT

 

[ckucia]

Are there any code issues with putting them inside? They would be within 12" of the edge of the slab. It's a pole building I'd eventually like to add interior walls onto. Within six inches would put them inside the wall cavity. At about 8-12", they'd be just in front of the future walls.

 

[Zeke]

Are there any code issues with putting them inside? They would be within 12" of the edge of the slab. It's a pole building I'd eventually like to add interior walls onto. Within six inches would put them inside the wall cavity. At about 8-12", they'd be just in front of the future walls.

Just provide access.