Another dumb sub panel thread. Where to get the power?

[David Hostetler]

Sorry, but since this is a different question, I figured it needed its own thread...

It looks like for my purposes, and to keep from having to upgrade my electrical when the itch for say a 3HP cyclone becomes too great to resist... I should be going with a 100 amp sub panel in the garage / shop.

Now how on earth do I tap 100 amps off of an already full main panel? I wouldn't think that would be wise... So how / where do I get my 100 amp service to the garage from?

Mind you, I have home wiring upgrade projects that ought to be taken care of, so upgrading the main is not out of the question, but to what?

I at present have a 150 amp main load center in my house with 16 slots, all of which are filled.

[David Helm]

You could replace a couple of single breakers with tandem ones. That would give you space for a 60 amp breaker to send to your shop (using appropriate sized wires of course). 60 amps should be ample for the shop.

[JohnT Fitzgerald]

You could replace a couple of single breakers with tandem ones. That would give you space for a 60 amp breaker to send to your shop (using appropriate sized wires of course). 60 amps should be ample for the shop.

Agreed. I had the same dilemna last year, and I ended up taking a few of the breakers to lights/outlets in the basement, and consolidating them with "tandems" (or "Mini's", or whatever they are called). This opened up 2 adjacent spaces, which I used to branch out a sub panel.

[Anthony Whitesell]

Will any circuits be freed when you move the equipment into the shop?

I have a basement shop and if I were to get a separate shop, several circuits would be freed in the main panel and combined in to the circuit headed to the subpanel in the shop. Will you have this situtation?

[Adam Strong]

Before changing any over to tandems, make sure your panel is rated for them... A 16 slot panel may only be rated for 16 circuits, making tandems a code issue.

[Dave MacArthur]

Also, when I had to do my permit work to put in my sub-panel, I had to do a whole-house amp review following some guidelines on how much amps a single family residence would/could normally use on a given set of circuits, and then show that my sub-panel demands did not exceed a resulting "available amps" from the main. If it did, I would have had to put in a larger main panel to the house.

They gave me some worksheets, but they matched the info I also found in the HomeDepot "Wiring" book on first steps in design. I recommend you buy that book, or at least A BOOK on home wiring, and read it. All the questions you're asking are answered in virtually every book on home wiring out there, you could save yourself some frustration in asking for all this info piecemeal, and just read a nice organized "how to plan and install a sub-panel for your workshop from start to finish" written by qualified electricians. Honestly, it was an extremely worthwhile investment for me when I sub-paneled.

You need to be sure your electrical service to the house CAN supply, to code, what you're planning on doing and be permitted, before you go too far.

[Alan Schwabacher]

One option is to make the shop your main panel with service directly to it, and reroute to have your house run off from that. That might be less change if your house can't handle the extra draw the shop needs.

Talk to the inspector to make sure whatever you do is legal in your area.

[George Clark]

I used a solution such as Allan suggested. My home had 100 amp service and the panel was full. I wanted some additional circuits in the house plus wiring to my shop. The electrician installed 200 amp service with a new panel and made the original 100 amp panel a sub panel. Solved the problem with room for future expansion.

[Jim Terrill]

I went a slightly different direction, there were some other basement outlets on the panel, I took those off the panel and added them to the subpanel, creating enough space for my 60a dual pole and keeping all basement outlets on the same panel.

[David Hostetler]

Will any circuits be freed when you move the equipment into the shop?

I have a basement shop and if I were to get a separate shop, several circuits would be freed in the main panel and combined in to the circuit headed to the subpanel in the shop. Will you have this situtation?

I am keeping the existing house lighting circuit for the shop lighting to keep it separate (I can throw the main in the sub panel off without losing my lights...), one wall outlet will be moved from the common wall, to actually 3 feet to the left of where I plan on having the sub panel to power my water softener / house Reverse Osmosis System backflush pumps.

I have about 6 110v single breakers, the rest are doubles, and the big amperage 220s for things like the furnace, water heater, AC, and stove...

[David Hostetler]

I used a solution such as Allan suggested. My home had 100 amp service and the panel was full. I wanted some additional circuits in the house plus wiring to my shop. The electrician installed 200 amp service with a new panel and made the original 100 amp panel a sub panel. Solved the problem with room for future expansion.

I am honestly considering doing something similar, but my original panel is pretty beat up, at least exterior wise. It is an exterior mount panel, and has been through a couple of hurricanes and tropical storms. A new box isn't THAT much money compared to the labor to get it done, and the hassle of getting the inspections done.

[Rob Russell]

Before you go down the path of turning the existing main panelboard into a subpanel, I'd take a close look at the wiring in the panelboard. When you convert from a main panelboard to subpanel, you need to isolate the neutral conductors onto an isolated buss. That may not be as easy as you think ifyou don't have long enough conductors inside the panelboard to do that.

150A is a lot of juice unless you're running a whole lot of AC, which you may be in Texas.

IMO, swapping the main panelboard for a larger one is the best solution. That gives you the ability to run your workshop panelboard and have plenty of space left over for other non-workshop circuits in the future.

[David G Baker]

What I did was swap out my main panel to 200 amp service, added two 100 amp breakers in the main panel, converted my indoor 100 amp panel to a sub panel fed by one of the 100 amp breakers in the main panel, added another 100 amp sub panel and mounted it next to the original indoor 100 amp panel. I separated the ground and neutral in each of the sub panels. I now have around 40 breaker slots or more. When I need to do some wiring, I kill one of the breakers in the main panel that controls the circuit I plan on working on. This way I still have power in the house being fed by the separate sub panel. This method is how I wired my home when I lived in California and it has served me well.
The 200 amp main has a bunch of open slots so I can add breakers in that box as well if I want to run another sub panel or just add a breaker for some exterior circuits.

[David Hostetler]

Before you go down the path of turning the existing main panelboard into a subpanel, I'd take a close look at the wiring in the panelboard. When you convert from a main panelboard to subpanel, you need to isolate the neutral conductors onto an isolated buss. That may not be as easy as you think ifyou don't have long enough conductors inside the panelboard to do that.

150A is a lot of juice unless you're running a whole lot of AC, which you may be in Texas.

IMO, swapping the main panelboard for a larger one is the best solution. That gives you the ability to run your workshop panelboard and have plenty of space left over for other non-workshop circuits in the future.

I am unfortunately in an all electric home. My entire neighborhood has no gas run to it. (Yeah I know the iron of living in coastal Texas, less than 20 miles from the refineries, and I can't get gas... So yeah, 150 amps to run everything really isn't all that much... I am getting a pretty good idea how to approach the electricians, so I will at least sound like I have a clue...

[Rob Russell]

... I can't get gas ...

There's always the freestanding propane tank route. My brother has either 2 or 3 125-pounders behind their garage. They use the bottled gas for heat, cooking, dryer, gas fireplace and have a line run to their gas grill.

It's possible that even that's not available in your area, although I'd be surprised if it weren't.