Quick Question on a Sub-Panel

[James-W]

My oldest daughter wants to remodel her three season porch. The porch was an "add-on" that was installed MANY years ago and she doesn't use it hardly at all because it is either too cold or too warm. There is no heat or air-conditioning out there so the porch has very little value, at least to her way of thinking it has very little value. There is one electrical outlet in the porch and there is one light operated by a wall switch. So she can't really much of anything out there at the present time. Mostly she has been using it for storage of stuff she seldom uses. She would like to put the three season porch to much better use and that's why she wants to do the remodel.

She wants to remove all of the windows that are currently there, put in one large "bump-out" window and one large sliding window. She wants to install two electric wall heaters, one on each end of the porch. She wants several wall outlets so that she can plug stuff in wherever she wants. She wants a ceiling fan and she wants some ceiling lighting, the type yet to be determined. We will be tearing the wall coverings down to the bare studs and revamping pretty much everything. Once we have the windows in and the walls, floor and ceiling, wired and insulated, we will be putting up drywall and I am not sure what she wants on the floor. I think she wants hardwood flooring, but I don't think she has made up her mind entirely on that.

I figure the easiest way to do this wiring is to run an 8 gauge cable from the main breaker panel to the three season porch and install a sub-panel. My question is two-fold, is this the best way of doing it and do I need to have two 8ft grounding rods for the sub-panel?

I thought maybe I could get by with running a 4 wire number 8 gauge cable, black, red, white, and ground, from the main breaker panel to the sub-panel. But then I thought I might need to have two separate ground stakes so I figured I would ask the experts here.

 

[yeldogt]

How big is the porch ?

I get that she wants to better use the space -- if you properly insulate it sounds like the perfect spot for a mini split. Even value windows are decent when it comes to energy efficiency. This way she gets heat and AC.. and at 3x for the same power vs resistance she may go longer into winter.

I'm sitting in my 15x 22 addition that I added a few years ago (lot of windows) -- it's coldish today and my radiant is off. The 12k mini is having no problems . What does she want to plug in ? Really don't need much power .. fans don't use much. I don't have a fan

Going back to your question -- the subs need 4 wire cable. No ground rod. The ground and neutral are not tied together in the sub-panel. The need for a main breaker on a small panel may not be required.

Be carful if the "bump out" window is one you buy ... and you are not building . They tend to be cheap and most people end up taking them out.

 

[mike93lx]

Two new 20a circuits would provide all of the power that you could ever need in a single living room, IMO. A sub is unnecessary and complicated, plus do you really want to be looking at an electrical panel in there?

 

[walrus]

No on the ground rods. BTW You posted this in wrong section

 

[James-W]

The porch is about 12 feet by 20 feet.

We will removing the wall going out to the porch and putting in a half wall. So the heat from the house and the air-conditioning from the house will be going out to the porch. We just thought that on really cold days a little extra heat out there would be a good idea. With the ceiling fan and the house air-conditioning we figured extra cooling out there wouldn't be a problem. With a well insulated porch and heat coming into the porch from the house, I doubt the heaters would run all that much, probably only on real cold days with lots of wind.

When the daughter and I sat down to think about this, we figured it would be a good idea to have one circuit for the lights and the ceiling fan. Then we would have one circuit for the receptacles on each wall, four walls means four circuits. Then we figured each wall heater should be on its own circuit. From the main circuit breaker panel to the porch, considering the way in which we would have to run the wiring, is somewhere around 75 feet.

Would it not be more advantageous to run one cable to a sub-panel and then branch off of it rather than run everything from the main panel? I realize a sub-panel may not look real nice, but we could put it someplace where it wouldn't be real noticeable.

 

[James-W]

No on the ground rods. BTW You posted this in wrong section

You are right, I screwed up. For some reason I was thinking about the heaters and this is the heating & cooling section . . . . .

 

[walrus]

The porch is about 12 feet by 20 feet.

We will removing the wall going out to the porch and putting in a half wall. So the heat from the house and the air-conditioning from the house will be going out to the porch. We just thought that on really cold days a little extra heat out there would be a good idea. With the ceiling fan and the house air-conditioning we figured extra cooling out there wouldn't be a problem. With a well insulated porch and heat coming into the porch from the house, I doubt the heaters would run all that much, probably only on real cold days with lots of wind.

When the daughter and I sat down to think about this, we figured it would be a good idea to have one circuit for the lights and the ceiling fan. Then we would have one circuit for the receptacles on each wall, four walls means four circuits. Then we figured each wall heater should be on its own circuit. From the main circuit breaker panel to the porch, considering the way in which we would have to run the wiring, is somewhere around 75 feet.

Would it not be more advantageous to run one cable to a sub-panel and then branch off of it rather than run everything from the main panel? I realize a sub-panel may not look real nice, but we could put it someplace where it wouldn't be real noticeable.

A circuit for each wall outlets is way over kill, what are you going to have for loads on those recepts? Electric heat will use a ton of juice and its a continuous load, best figure out how many watts is going to your heat. I would think about a mini split heat pump. More money but heat and AC for way less killowatts.

 

[mike93lx]

yeah, that's crazy.

1 circuit for outlets, separate one for lighting. If you are going to run a big heater, like a baseboard, it will likely be 240V and require it's own circuit.

the only advantage to a local sub is to minimize runs back to the main panel. if that run isn't hard, just home run the 2-3 circuits.

 

[nafterclifen]

I'm about to build a 12x20 addition and will be pulling 3 home runs from my panel...

(1) 12-2 for outlets
(1) 14-2 for lighting
(1) 12-2 for mini-split

 

[That1Guy]

Depending on your particular situation, would it be easier to run a circuit for a mini-split or to duct heat and AC to the porch? That would decide which way to go on that part of it for me anyway. Keep in mind that adding that room onto your existing HVAC system will probably take away from the rest of the house to one degree or another and the original design of your system wasn't "spec'd" for that. Whereas a mini-split will be completely isolated from the home system. This might be the difference between that room struggling to keep cool or warm and being able to keep it cool enough on those sweltering hot summer days to make the neighbors jealous. Just sayin.

Also, I agree with the others that a 20a circuit for lights/fans and another 20a for the outlets should be plenty for a room that size IMHO. But again, it all depends on what your particular situation calls for. Determine where the sub panel would be and ask yourself if it would be easier to run 3 small circuits from that location to the main panel or to run one large circuit plus install a subpanel. Again, it'll all depend on your specific situation. Either way will work. I'm just trying to picture what advantage the subpanel would give you. Maybe a hot tub in the future? If so, take that into account when you run the feed to the sub and be sure to go big enough for future upgrades. In the end, it's up to you.

I'm interested to hear how this turns out. Please be sure to post back when it's done and let us know what route you ended up taking. That way everybody learns from your experience.

 

[Showkey]

Guess the real question is the porch going to be 3 or 4 season ?

Baseboard heat is less than $100. Mini split $$$$.$$

Another vote for no sub panel.......or.........sub panel in the basement near the porch if the run back to the main panel is long or inconvenient. If the main panel is full, sub install next to the main ?

My porch is 12’x24’, 3 season, Insulated floor and ceiling, no heat, no AC, ceiling, fan all windows and screens, in the shade. Sunny Winter 20* day Inside 70*, Sun goes down temp drops like a rock.

 

[mobetta]

you already have a lighting circuit.
you already have an outlet to pull more outlets from. If you know there will be a big load in this room MAYBE it makes since to run a separate outlet circuit.
so you need to address the HVAC.
if you are connecting this space to the existing house like it sounds, the cheapest and easiest may be to tie in to the existing hvac.

electric baseboards are cheap to install and purchase but cost you a lot long term.