House as sub-panel

[ChevyJr]

I posted this in an inactive thread, so I hope its not too annoying to post again.

"I currently am going through this scenario and wanted to run through it to receive feedback before I complete it this Memorial Day weekend.

The main power will now be at the garage and the house will become the sub-panel. I understand that I have to remove the bonding screw in the house to isolate the neutrals from the grounds and then add a ground bar. The grounds will move to the ground bar and the neutrals can stay where they are.

I have the Square D Homeline 100 amp Load Center

http://www.homedepot.com/p/Square-D-...-204836397-_-N

It has a main breaker on top, which I assume I need to remove and replace with two lugs, both being the hots from the 100amp fuse in the garage (the garage will be 200 amp service). As far as the feeder wire from the garage to the house, I was thinking 3 wire SEU (#2 aluminum or #4 copper by code, think aluminum since its easier to bend) would be best. I do not believe I need 4 wire as the current main power, at the house, is grounded to two ground rods so I would only need the two hots and neutral wire.

As I am sure someone may wonder why I am going this route, the energy company is requiring me to set it up this way because pulling a power sources from either pole (2 poles in the back yard) in my back yard cross over the top of my garage which violates code. I could have them place a third pole in the other corner (back yard kind of comes to a point creating three plausible locations) but that's much more expensive than chasing my tale trying to move everything.

I will posts photos as soon as I get home this afternoon. Any help is greatly appreciated."

 

[Cmreschke]

You must leave the main breaker in. It is now a disconnect which is required for seperate outbuilding panels. You must run 4 wire to this panel and have the ground rods as well. You do not bond the neutral to geound.

 

[CNGsaves]

Too little information . . . . .

a) What Country are you in ??
b) Distance between garage and house ??
c) Plan on using conduit for that bury ?? Size ??
d) Loads in both Garage and House ??

GJ Sparky's will give you detailed info if enough information provided.

UPDATE GJ Profile with a Location.

 

[ChevyJr]

a)I'm in Denver, CO. Sorry fairly new. I will update that asap.
b)The distance is approximately 70 ft between house and garage
c) conduit, 1"
d) House: 100amp Garage: 200amp

Too little information . . . . .

a) What Country are you in ??
b) Distance between garage and house ??
c) Plan on using conduit for that bury ?? Size ??
d) Loads in both Garage and House ??

GJ Sparky's will give you detailed info if enough information provided.

UPDATE GJ Profile with a Location.

 

[Dick in Wisconsin]

Don't feel bad about bringing this to the forefront. I suspect lots of guys are in the same boat. POCO is in the back of the property. New garage/shop going in. Increasing service. No need to rewire the house when you can put the main in the shop and have the house as a subpanel.

You're doing exactly what I did when we built the new shop. We had to run in a new service from the pole (320amps). From the pole to the shop was 30'. From the pole to house was 75'. Electrician (a very good one) said we should go from the pole to shop with a huge panel and make the house a sub-panel off the shop.

I don't know what kind of wire he used. He did leave the main breaker on the panel in the house because as another poster mentioned each building needs to have a main disconnect.

d) House: 100amp Garage: 200amp

I think Mr. CNG was asking for the expected "load" and not the capacity of the services. Or maybe you did answer the question correctly.

 

[wyliesdiesels]

I posted this in an inactive thread, so I hope its not too annoying to post again.

"I currently am going through this scenario and wanted to run through it to receive feedback before I complete it this Memorial Day weekend.

The main power will now be at the garage and the house will become the sub-panel. I understand that I have to remove the bonding screw in the house to isolate the neutrals from the grounds and then add a ground bar. The grounds will move to the ground bar and the neutrals can stay where they are.

I have the Square D Homeline 100 amp Load Center

http://www.homedepot.com/p/Square-D-...-204836397-_-N

It has a main breaker on top, which I assume I need to remove and replace with two lugs, both being the hots from the 100amp fuse in the garage (the garage will be 200 amp service). As far as the feeder wire from the garage to the house, I was thinking 3 wire SEU (#2 aluminum or #4 copper by code, think aluminum since its easier to bend) would be best. I do not believe I need 4 wire as the current main power, at the house, is grounded to two ground rods so I would only need the two hots and neutral wire.

As I am sure someone may wonder why I am going this route, the energy company is requiring me to set it up this way because pulling a power sources from either pole (2 poles in the back yard) in my back yard cross over the top of my garage which violates code. I could have them place a third pole in the other corner (back yard kind of comes to a point creating three plausible locations) but that's much more expensive than chasing my tale trying to move everything.

I will posts photos as soon as I get home this afternoon. Any help is greatly appreciated."

Assuming this is a detached structure, u need a main disconnect so leave the main breaker. SEU and SER CANNOT go underground. So u need different wire

Since the house panel will now be a subpanel it MUST be converted to 4-wire.

You are confusing the 2 types of grounds. Grounding electrodes and EGCs are 2 different animals and serve different purposes. Grounding electrodes are mainly for grounding lightning and are required for detached structures but they DO NOT take the place of an equipment grounding conductor that is needed between the panels.

Read this article, it should help clear up the confusion!

http://www.electriciantalk.com/articles/the-confusion-of-the-term-grounding/

 

[theoldwizard1]

Since the house panel will now be a subpanel it MUST be converted to 4-wire.

The short, less technical version of this is, the "ground" and neutral buses in the house load center must be separated. (NOT bonded.) You may have to purchase a ground bar kit for your load center (not expensive).

 

[theoldwizard1]

As wyliesdiesels said, you will need 4 wire cable to the house. Without changing the load center in the house (except for unbonding the ground/neutral), if you are willing to feed it through a 90A breaker, you can use MHF and save a few bucks.

MHF can be used underground (either direct buried or in conduit), but ABOVE ground, it must be in a conduit.

 

[Cmreschke]

a)I'm in Denver, CO. Sorry fairly new. I will update that asap.
b)The distance is approximately 70 ft between house and garage
c) conduit, 1"
d) House: 100amp Garage: 200amp

1" will probably be too small. Go with 1 1/2" for fill and ease of pull.

 

[Falcon67]

1" will probably be too small. Go with 1 1/2" for fill and ease of pull.

That was my first thought. 1 1/2" or 2" better. 2" especially if it has bends. Double especially if it's MHF. I'd not even try with 1".

 

[checkthisout]

Grounds = Bare copper wires

Neutral = White wires.

You need 4 wire service coming from the garage to the house now.

You will separate your neutrals and grounds in the house panel now. You will add a grounding bar kit or your panel might be setup to go this way by shifting wires from one bar to another and removing a bonding screw.

The 4th wire from your garage will attach to the same bar as the one you will put all the bare copper wires on.

You will add two ground rods at the house and attach the lead to the same bar as the bare copper wires and 4th wire going to garage. The screw holding the bar down will connect the bar electrically to the metal panel.

You will remove the bonding screw that is currently electrically connecting the bar holding the ground and neutrals to the panel and place all your neutrals on this bar.

 

[CNGsaves]

That 1" conduit should just be for low voltage like CATV, internet, phone, security, etc. Try to keep 12" separation between the power conduit and this low voltage conduit - - - like trench deeper with power on bottom in sand, and backfill before the low voltage conduit.

+1 to go with 2" plastic electrical conduit for your buried power feed to house. This will handle likely wire of MHF 2-2-2-4 aluminum that can supply the house with 90A.

 

[ChevyJr]

Great. This is extremely helpful and something I think Wilie was getting at as well.

I understand the placements of hots and neutrals. Thanks guys.

GROUNDS: SO the 4-wire service connector is grounded in the house to the ground-bar, as well as the two grounding rods (already existent as that house where the meter was) to the same ground-bar which is separate from the neutral bar (not bonded).

Back at the garage, where the new meter is being moved to, the meter is grounded via 2 ground bars connecting by copper wire and separated by at least 6 feet. The feeder wire, connected to the house, needs to be connected to the bonded (neutral and ground)bar. That bar is grounded to the Ufer ground, 1/2" rebar sticking up from the concrete foundation of the detached garage by copper wire. Am I missing any grounds?


CNCSaves: Do homes have any problems not having that extra 10 amps? Nothing big goes on in the house the really creates that much load outside of the dishwasher, washer dryer, microwave and fridge. Normal household appliances.

If I don't use MHF, would this fit the bill?

http://www.homedepot.com/p/Southwir...Stranded-AL-URD-****-Cable-55417301/202250411

It may even allow me to skip the below ground conduit step if I can find it in shorter lengths. Although if everyone has used conduit, I think I may simply follow suit.

Too little information . . . . .

a) What Country are you in ??
b) Distance between garage and house ??
c) Plan on using conduit for that bury ?? Size ??
d) Loads in both Garage and House ??

GJ Sparky's will give you detailed info if enough information provided.

UPDATE GJ Profile with a Location.

Grounds = Bare copper wires

Neutral = White wires.

You need 4 wire service coming from the garage to the house now.

You will separate your neutrals and grounds in the house panel now. You will add a grounding bar kit or your panel might be setup to go this way by shifting wires from one bar to another and removing a bonding screw.

The 4th wire from your garage will attach to the same bar as the one you will put all the bare copper wires on.

You will add two ground rods at the house and attach the lead to the same bar as the bare copper wires and 4th wire going to garage. The screw holding the bar down will connect the bar electrically to the metal panel.

You will remove the bonding screw that is currently electrically connecting the bar holding the ground and neutrals to the panel and place all your neutrals on this bar.

 

[CNGsaves]

OP . . . depending on what electrical loads you have in house (ie do you have NG for heat and HWH ??), then big draws would be A/C along with electric stove and possibly electric clothes dryer. Provide all those "loads" and GJ Sparky's will give you better details. The MHF has 90A limit when it's supplying a subpanel. Different wire could be used if you absolute need 100A based on load calc.

2" plastic conduit for your buried power between garage and house will be cheap long-term insurance. If some changes occur later, ability to re-pull different wire would be easy if you have the conduit - - - say you convert to all-electric house, backhoe operator cuts it in half, etc.

GJ Sparky's can explain benefits of MHF 2-2-2-4 Al as it can be one continuous "wire" between both buildings. Would just need conduit when above ground and all the way to panel in conduit also (thus best practice is conduit end-to-end).

 

[wyliesdiesels]

Great. This is extremely helpful and something I think Wilie was getting at as well.

I understand the placements of hots and neutrals. Thanks guys.

GROUNDS: SO the 4-wire service connector is grounded in the house to the ground-bar, as well as the two grounding rods (already existent as that house where the meter was) to the same ground-bar which is separate from the neutral bar (not bonded).

Back at the garage, where the new meter is being moved to, the meter is grounded via 2 ground bars connecting by copper wire and separated by at least 6 feet. The feeder wire, connected to the house, needs to be connected to the bonded (neutral and ground)bar. That bar is grounded to the Ufer ground, 1/2" rebar sticking up from the concrete foundation of the detached garage by copper wire. Am I missing any grounds?


CNCSaves: Do homes have any problems not having that extra 10 amps? Nothing big goes on in the house the really creates that much load outside of the dishwasher, washer dryer, microwave and fridge. Normal household appliances.

If I don't use MHF, would this fit the bill?

http://www.homedepot.com/p/Southwir...Stranded-AL-URD-****-Cable-55417301/202250411

It may even allow me to skip the below ground conduit step if I can find it in shorter lengths. Although if everyone has used conduit, I think I may simply follow suit.

that is URD and not allowed to be ran inside because the insulation is not flame resistant in conduit or not...

What loads do u have in the house?

 

[Falcon67]

If it's all electric, 90A might not do it. Our 2001 Goodman electric 3.5 Ton HVAC unit pulled 60A with the heat on.

 

[Cmreschke]

What's the square footage on your house, and what electrical built in appliances do you have?

 

[ChevyJr]

The house is 1700 square feet. The appliance include:

Frigidaire Gallery Fridge, Microwave, Stove/Oven, and dish washer
2 ton A/C unit; furnace

Gas water heater

What's the square footage on your house, and what electrical built in appliances do you have?

 

[ChevyJr]

What other options aside from the MHF are there if SER, SEU, UDR don't work?

 

[CNGsaves]

Still not providing enough info . . .
. . .
. . . . . . Is the furnace on Natural Gas or Electric ??
. . . . . . Any plans to have Electric dryer versus NG ?? Which is it now ??

 

[ChevyJr]

Natural gas for both. Sorry.

 

[ChevyJr]

Still not providing enough info . . .
. . .
. . . . . . Is the furnace on Natural Gas or Electric ??
. . . . . . Any plans to have Electric dryer versus NG ?? Which is it now ??

Also electric washer and dryer.

 

[wyliesdiesels]

What other options aside from the MHF are there if SER, SEU, UDR don't work?

Individual conductors such as THWN cu or XHHW AL wire...

 

[Cmreschke]

Ok if I'm doing this correctly (it's been a really long time) I'm at like 27 amps lighting load demand. That doesn't include built in appliances since I don't have all of that information. My opinion is that 90 amps is plenty fine.

 

[ChevyJr]

Major Appliances

Refrigerator 155v * 15amps = 2325 watts
Range 240v * 40amps = 9600 watts
Microwave 120v * 15amps = 1800 watts
Dishwasher (connected to food disposal) 120v * 20amps = 2400 watts
Air Conditioning Unit (Min) 197v * 16.7 = 3289.9 watts (Max) 253v * 25amps = 6325 watts
Furnace Fan (approximately) 700 watts
Washer 120V * 15 amps = 1800 watts
Dryer 5400W

 

[Cmreschke]

So you have 240 v dryer and range. Thought you said it was gas earlier.

 

[ChevyJr]

I did. I was incorrect. My apologies. So I went and checked all my major appliances.

 

[Falcon67]

I'm thinking you should plan for 150A at least. Now FWIW, we have "200A service" at our house. The poco had no issue with attaching a 100A sub panel off our meter base for my MHF run to the new shop. 200A panel/breaker inside from the meter, 70A in the sub for the shop, 100A 20 space panel in the shop.

 

[Cmreschke]

Is your microwave built in? Fridge is not counted. Washer not counted. Range is 8000 watts or name plate whichever is greater so I'll assume you didnt pull it out and look. Probably 8000 watts for calc. Furnace is name plate I believe, I'll have to look up again about the disposal and dishwasher. I'm still thinking 90 amps is plenty sufficient.

 

[ChevyJr]

Falcon: 150 amp service at the house?



Cmreschke: Microwave is upper mounted built-in. All of the number above were numbers from the manuals provided with each appliance. We just moved in a few months ago so everything is new (and how I mistook it the dryer for gas as it was in our previous place). But if you think 90 is enough then I may move forward using the MHF CNGsaves suggested. Thanks GJ.

GJ Sparkys: Let me know if anyone can think of a reason why not to move forward with the MHF.

Is your microwave built in? Fridge is not counted. Washer not counted. Range is 8000 watts or name plate whichever is greater so I'll assume you didnt pull it out and look. Probably 8000 watts for calc. Furnace is name plate I believe, I'll have to look up again about the disposal and dishwasher. I'm still thinking 90 amps is plenty sufficient.

 

[My Old Tools]

That was my first thought. 1 1/2" or 2" better. 2" especially if it has bends. Double especially if it's MHF. I'd not even try with 1".

MHF will not pull through 1", and it's tough through 1.5". DAMHIKT. Go with 2" or use copper.