New construction wiring question

[Paddy]

I built an add on attached garage. I ran a sub-panel because the distance to run all the additional circuits. By doing this, I just ran one large wire. Not sure if there is any less copper by running one large or six small runs. The sub-panels are not expensive. With regards to grounding; I understood if the distance to long, seperate isolated grounds are required. This is due to safety because current is looking for the 'shortest' path.

I will be building a concrete home and regardless of copper savings, making less physical runs through concrete walls/floors will be an advantage. In Europe, it's quite common to see a small breaker box in each room.

 

[_RaT_]

Here is a link from another poster here: Adding New Electrical Circuits - Installing A Sub-Panel - An Overview

Rex Caudwell has good book "Wiring a House".. Pay attention to the part about the type of sub panel. I have my favorite and I have my least favorite. Its one area I really agree with him on. Not all panels be they sub panels or meter/mains are built equal. Give me room for the neutral and the ground bus.

 

[BobRip]

I have a rancher which is about 90 feet long. The power comes in on one end. I have a panel there and a main breaker that runs to another panel which is in the utility room and near the kitchen. This second panel is not a subpanel. I have a third panel in the garage which is run off of the first panel and is a subpanel. I did this to save on voltage drop and wire length. I think you have a good concept, but I would put it on the second floor, not in the attic so that you can easily reset breakers. Run lots of spare wires into the attic for future expansion. You can also run some conduits into the attic for future use. You should also consider that 100 amps is not a lot. My subpanel in the garage is 200 amps. I figured that was overkill, but I now only have two spare slots. I don't really have a lot of load on it, but I do have a lot of circuits. A 200 amp panel is not much more expensive than a smaller panel. You do not have to feed it with 200 amps. I am using 125 amps and have never had a trip. Just some thoughts.

 

[EddieWalker]

I'm confused on this.

You have a main breaker box in the basement and you will power the basement from here. Then you want to put another sub pannel upstairs on the main level to run the wire for that floor? Is that right?

How far will the sub pannel be from the main breaker? And more importantly, where will you locate the subpanel? One of the reasons for putting the main breaker box in a garage is that it's able to be accesable without ruing the look of a wall. Closets are bad places to put subs because of access and in some places, it's illegal.

I'd really consider what the advantages are for the subpanel because I don't see any. The price of wire isn't significant for short distances like what you have. I doubt it will be much of a difference copared to the price of the pane panel, larger wire and labor to install it.

If you have plans of any future needs, just run the right sized wire from the main to where you will need it. Don't connect it, just labe it and leave it loose in the panel. If you can't leave it in the panel because of code, leave it where you can easily get it into your panel when you need it.

You can do this with wire to every location you might want it in the future. I did this with four wires for my outdoor lighting and a shed that I'll put in someitime in the future. I ran the wires into the panel and left them there and labeled each end. When I put in my lights, I'll be able to easily wire them up.

Good luck,
Eddie

 

[randy41]

i think he means he has 3 levels all together counting the basement.

 

[5030tinkerer]

Yes, I have three levels counting the basement. Service will be coming in one end. I haven't yet designed the circuit layout, but am close to doing that.

This need for an isolated ground has me baffled, though. I am not in an area where I will have any inspectors, but want to do it right as well.

The idea of putting a subpanel behind a door has quite a bit of merit, though I will have pull-down stair attic access, plenty of standing room up there, and would then benefit from not having the panel mounted inside a finished wall.

In absence of a subpanel, some of my circuit runs would be upwards of 100' feet away.

 

[_RaT_]

I built an add on attached garage. I ran a sub-panel because the distance to run all the additional circuits. By doing this, I just ran one large wire. Not sure if there is any less copper by running one large or six small runs. The sub-panels are not expensive. With regards to grounding; I understood if the distance to long, seperate isolated grounds are required. This is due to safety because current is looking for the 'shortest' path.

I will be building a concrete home and regardless of copper savings, making less physical runs through concrete walls/floors will be an advantage. In Europe, it's quite common to see a small breaker box in each room.

Paddy, let us know about this concrete home. Is it ICF?

 

[_RaT_]

In absence of a subpanel, some of my circuit runs would be upwards of 100' feet away.

Perfect reason for a subpanel. With 100 foot runs, the combined to/from length of 200 feet plus a high current flow and you will have a pretty high voltage drop. I think the convenience of having an indoor subpanel to turn circuits off or reset a tripped breaker is a welcome benefit.

 

[EddieWalker]

In absence of a subpanel, some of my circuit runs would be upwards of 100' feet away.

100' runs in a 1,600 square foot home is just amazing. I guess it's just not sinking in for me, but with that kind of distance from your main panal, I'd put in a sub panel too.

You must have a very, very long and narrow home. What are the dimensions of the house?

Good luck,
Eddie

 

[_RaT_]

You must have a very, very long and narrow home. What are the dimensions of the house?

Good luck,
Eddie

I was thinking the same thing...