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# Sub-Panel Installation

#1
08-07-12, 08:43 PM
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Sub-Panel Installation

In all honesty, I don't know exactly where to start explaining this.

This has been something that has kept me up several nights. My father who will be climbing in to his seventies in a couple of months, owns a home that dates back to the late 1800's to early 1900's.

When him and my mother purchased the home it originally had only a 60amp service coming in from the pole, and at that time everything in the house was routed to a fuse box with nothing more that six fuses.

Well shortly after getting on my own two feet, one of the first things I did was purchase a 200amp main panel for their home, under the condition that they have some one install it for them, which they promptly did.

Now here's where the problem's come in, this two story home with basement, totaling close to 3000 sq ft. everything is routed back to that one main panel. With junction boxes galore, to that point it's scary to think how has this house stood for so long.

So what I'm thinking about doing, with the hopes that it's possible. Is to put each floor on to it's own sub-panel. For one so that the main panel isn't so crowded. And two, if for some reason the breaker for the lights on the second floor was to trip, it would conveniently be there on the second floor, not in the basement. In which my father agrees with me.

Though the only things at this moment that are stopping me, are calculating the load for each particular panel, selecting the correct feeder size/gauge, and whether or not there is anything in NEC that states a sub-panel "can not" be installed near a water heater or furnace. For example one of the panels I figured up (the basement):

Refridgerator-2.8amp = 336 watts
Washer-7amp = 840 watts
Gas Dryer-6amp = 720 watts
One Man Whirlpool-10.5amp = 1260 watts
Drill Press-12amp = 1440 watts
Table Saw-13amp = 1560 watts
Lathe-6.2amp = 746 watts
Deep Freeze-1.6amp = 186.5 Watts
Furnace-Unknown

Then there's a total of 13 wall outlets (with more planned at a future date) and 13 lights (4 Florescent)

Note: This panel would be approx 20-25 feet from the main panel, all indoors.

#2
08-08-12, 03:04 AM
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A 200 amp panel should handle the loads you have without a problem. I would not go to the trouble of putting in separate sub panels. Rather, just rewire it all from the panel and dedicate certain circuits like the big items, leaving separate lighting and receptacle circuits for each floor. Eliminate or secure the junction boxes as much as possible by your rewiring.

#3
08-08-12, 05:30 AM
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If you want to proceed without going into a demand load calculation you could install a 60 to 90 amp subpanel on each floor. Leave the heavy loads like AC, heat pumps, stoves etc in the service panel.

#4
08-08-12, 12:27 PM
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I wouldn't bother with a subpanel for each floor. You probably won't find a good (good = code compliant + aesthetically appropriate) place for a subpanel. Also, the wires will still have to run from one side of the house to the other. You may consider a subpanel on the other side of the basement, but consider where most of your circuits will be originating. No reason to put a subpanel somewhere that just has a bedroom and living room.

Also remember, upgrading some of these circuits may require bringing rooms up to current code. Just adding a subpanel probably wouldn't, but remember this as you get to the bathrooms, kitchen, and other rooms.

Last edited by Zorfdt; 08-08-12 at 12:29 PM. Reason: Added info
#5
08-08-12, 05:07 PM
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Also remember, upgrading some of these circuits may require bringing rooms up to current code. Just adding a subpanel probably wouldn't, but remember this as you get to the bathrooms, kitchen, and other rooms.
Several of the rooms, e.g. Kitchen, Living Room, second floor bathroom, and two bedrooms were already rewired with the current romax. Unfortunately when the Kitchen and Living Room was done, instead of wiring all the outlets in parallel. They just pulled the wire down through the sill of the wall to a junction box, then proceeded to the main panel.

Only way I can think of fixing this with out ripping the walls back out is with a fish tape, then wire all outlets in parallel.

You probably won't find a good (good = code compliant + aesthetically appropriate) place for a subpanel.

Meaning? That's why I'm questioning the location of the one in the basement. I spent hours looking through 2008 NEC for location information in relation to gas water heaters and furnaces.

Only viable information I was able to get, was from a contractor at my job who told me, "
that you have a 30" wide by 36" workspace in front of the panel. The measurement can begin on the left side of the panel, and extend 30" to the right, or can start on the right side of the panel and extend 30" to the left, or can be centered directly in front of the panel."

If you want to proceed without going into a demand load calculation you could install a 60 to 90 amp subpanel on each floor. Leave the heavy loads like AC, heat pumps, stoves etc in the service panel.

Beings I'm some what on the fence with this, that's kind of the direction I was leaning. Move all the "low demand" items, wall outlets, lights, etc. to a sub-panel, and leave as you state it all the "heave loads in the service panel."

I was looking this evening, the panel I purchased them roughly ten years ago could accommodate forty breakers. At this moment there is only six slots vacant, most of the occupied slots are either outlets or lights. Two are consumed by a stove, two by an A/C, while another two by a welder.

Yet when I trace all these feeders coming out of the panel, most of them run to junction boxes that supply at the most three or four outlets, while some of the junction boxes have feeder going out to another junction box. And several of these feeders, are 14/2 yet once they get to the junction box there will be three or four 12/2 leaving the junction box.

Something else I didn't mention is, that currently there is no service available for an electric dryer. My father has never believed in using one because of the demand they have. Though ironically, he uses an electric stove practically every day. Looking down the line, my understanding is that such service has to be installed in order for a home to be up to code. Though I could be wrong.

#6
08-08-12, 05:11 PM
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Looking down the line, my understanding is that such service has to be installed in order for a home to be up to code
I am not aware of any codes that require a home to have any laundry circuits at all.

#7
08-08-12, 07:17 PM
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There is no code to have an electric dryer because many people use gas. That same goes for the stove as well.

The contractor you talked to is 100% correct. Those are the clearances that are required.

While in a home, receptacles, switches, and other outlets (defined by the NEC) are mostly daisy chained because of the requirement for all junction boxes to be accessible. It is just easier when a house is built. When retrofitting a home with new electric J-boxes are almost unavoidable. You could daisy chain the new receptacles but that would be much more work = more cost. J-boxes are a simpler, cost effective, code compliant, and perfectly safe way to do the job.
At your work, take a look above the suspended ceiling and you will find TONS of j-boxes.

I agree with the others, adding sub panels to each floor is a waste of time, money and square footage. If you need more circuit spaces add a sub panel next to the main panel.

#8
08-08-12, 09:01 PM
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There is no code to have an electric dryer because many people use gas. That same goes for the stove as well.

Thank you for correcting me on that one.

J-boxes are a simpler, cost effective, code compliant, and perfectly safe way to do the job.
How would I explain/ask this.....when using J-boxes, especially with receptacles. Is there anything I need to take in to consideration for appliances such as washer/dryer, refrigerator/freezer? Some sources I've read state to put them on their own circuit, while others state not to. And even though most of the existing J-boxes are metal/galvanized would PVC be a better option?

And when it comes to dividing/grouping the receptacles, with the thought in mind that some items, per say table saw will be drawing in excess of fifteen-hundred watts. Is there a way to calculate the max. number of receptacles for that circuit? Or is there just a standard threshold, per amp rating of circuit? e.g. 15A, 20A. Because very rarely is the drill press running when the table saw is running and vice verse.

#9
08-09-12, 05:32 AM
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Steel boxes are best used with a steel/aluminum wiring method. (EMT, Flex conduit, AC/MC cable) You can use them for Romex but you must ground each box. Plastic boxes may only be used with a non-metallic wiring method like Romex.

NEC requires some receptacles to be on their own circuit. Laundry, Bathrooms, and kitchen small appliance (counter top) to name a few. The NEC does not require putting a fridge on its own circuit but some manufactures/people suggest it. A circuit can be loaded 100% of a noncontinuous load and only 80% of a continuous load. A continous load is one that will be runnig for 3 hours or more.

For calculating a load on a circuit you should find the nameplate on the machine that lists the watts or amp draw. Multiply watts by the voltage to find amps.

#10
08-09-12, 06:27 PM
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Steel boxes are best used with a steel/aluminum wiring method. (EMT, Flex conduit, AC/MC cable) You can use them for Romex but you must ground each box.
Unfortunately ...... the majority of J-boxes in the basement are steel boxes and all but a few are "Not" grounded.

A continous load is one that will be running for 3 hours or more.
Beings you've defined the difference between a noncontinuous load and a continuous load. Could a ceiling fan be classified as a continuous load? During the summer months, they never get shut off.

While looking at the scope of this project this evening, there was one circuit which I noticed that ran to a J-box in the basement. Then from there it went directly in to a "power strip" consisting of eight individual receptacles, from there it went on to a receptacle on the wall and stopped.

While there was another circuit that went up to a receptacle in the dining room which is on one side of the room. Then come back down in to the basement, to run over to another receptacle on the other side of the dining room and stopped.

I have a feeling I'm going to find a lot more (fill in the blank) like this.

#11
08-10-12, 03:29 PM
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Could a ceiling fan be classified as a continuous load?
Yes. Ceiling fans and general lights are mostly considered a continuous load. On the good side, a ceiling fan uses very little power so it is not a big deal. 12 cans in a room would be more of a concern.

#12
08-10-12, 05:06 PM
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Unfortunately ...... the majority of J-boxes in the basement are steel boxes and all but a few are "Not" grounded
I don't think that's bad thing, you can ground those that need grounding. Call me old school, but I consider plastic boxes a lot like PVC conduit, it's great stuff but I don't want to see it. PVC conduits are best underground and out of my sight and plastic boxes should be inside walls, also out of my sight. I prefer metal boxes that are visible, but they do need to be properly grounded. This is just my opinion though.