Wiring for future 220

[isddarms]

I'm wiring the some additional circuits in the <s>shop</s> garage of our new house. What do I need to consider to wire a outlet that will be 110 now but will want to convert to 220 later?

[LCHIEN]

A 220V household outlet (single phase) is really just
Two phases of 110.

The power that comes into your house is actually two legs of 110 and a neutral which is normally tied to ground. Around half your 110 AC outlets are tied to one leg and the other are tied to the other leg.

When you need 220 they use both legs and no neutral.

I believe all you need to do in build a 110V circuit in the normal fashion. When you want to convert it, you will need to replace the breaker with a double pole breaker and the outlet with a 220V outlet.

[LJR]

isddarms, 120 volt receptacle circuits are typically run with #12 wire, three wires: black, white, ground. As LCHIEN says, when it comes time to change to 240 volt you re-mark the end of the white wire and use it as a "hot".

It's easier to add more wire now instead of find out you need em later. That #12 will limit you on current draw. Think about pulling in #10 wire with four wires: black, red, white ,and ground. That will allow for just about any machine you're likely to put in a home shop.

On your original installation you may find that #10 wire too big to fit on your 120 volt receptacle. Splice in a "pigtail" with smaller wire that will fit the receptacle (make sure the breaker is sized to protect). Put tape or wirenuts on the unused conductors and stuff them back in the box til you need them.

http://www.selfhelpandmore.com/homewiringusa/index.htm

[isddarms]

Thanks for the advice. My intention was to do just ad LCHIEN mentioned, but I wasn't sure if I needed a neutral in addition to the two hot legs. As for stepping up to #10 wire, I just don't see that I'll ever use any equipment that's going to run more than 20 amps @220.

[Stick]

quote:Originally posted by isddarms

Thanks for the advice. My intention was to do just ad LCHIEN mentioned, but I wasn't sure if I needed a neutral in addition to the two hot legs. As for stepping up to #10 wire, I just don't see that I'll ever use any equipment that's going to run more than 20 amps @220.

I wouldn't run it without a neutral. Who knows what you may acquire later that may need it. Same with the #10. In fact, I'd go with #8 or even #6. You may someday decide to take up welding and want a 50A circuit. If the wire's already there, it's easy. Or you might want a spare range in the shop for heating parts, etc. You never know. Maybe you'll get a great deal on a 10hp compressor or a big metal lathe.

Previous owner of my place installed welder outlets all over, but only sized them for 40 amps, what his buzzbox needed. Mine draws more than that on high current, and I trip the breakers if I try to run very long. I woulnd up installing real 50 amp circuits as well. All because he tried to save a few bucks on breakers and wire.

[Hellrazor]

If i was you i would plan for the future before i even start the project.

As a general rule:
#14 wire is good to 15Amp
#12 wire is good to 20Amp
#10 wire is good to 30Amp

I would consider running a subpanel to the shop/garage. Then you dont have to worry about wanting 220 down the line and messing with the wires. I know this sounds like overkill, but i just did it with my workshop. I NEED 30amp for what i have now, but i ran #6 so i can upgrade to 50A if needed. All depends on how far the run is from the main panel on the cost of doing this. Running 1.5" conduit, a full size Square D QO panel, 3 #6 THWN and 1 #8 THWN ground 130' cost a decent ammount of money. If your garage is attached (as it sounds) you will be far better off.


For those of you who have driven grounding rods in for detached garages i have a nice trick for you...

Take a palm nailer and install the largest head you have on it and palm nail the ground rod home. Its entertaining, easy and fast.

[isddarms]

Fortunately, the electrical panel is right in the <s>shop</s> garage. I'm trying to do a reasonable amount of amount of planning for the future without going way overboard.

In addition to two general purpose circuits for outlets, I'm running stand-alone circuits for the major power tools I currently have or plan to acquire in the near future - especially those that have the potential to run simultaneously (table saw, air/compressor, dust collector).

[LCHIEN]

I would think that leaving the wire at 12 ga. would be plenty.
When and if you changeover to a 220V circuit, you will be able to deliver twice the power on the same wire (same amps, twice the voltage). It's easier than
changing the wire - that's why you do it (go to 220V instead of chanign wire).

[don_hart]

I suggest you just pull some 12/3 romex. I would go ahead and get a double pole breaker and put in a double outlet box wired with each outlet fixture wired at 110v one on each phase. When you are ready to use 220v all you need to do is turn off the circuits and replace one or both of the 110v outlets with a 220v outlet. This way you will not have to buy a different breaker when you go to 220v and you will only have to work in the panel once.

[LCHIEN]

quote:Originally posted by don_hart

I suggest you just pull some 12/3 romex. I would go ahead and get a double pole breaker and put in a double outlet box wired with each outlet fixture wired at 110v one on each phase. When you are ready to use 220v all you need to do is turn off the circuits and replace one or both of the 110v outlets with a 220v outlet. This way you will not have to buy a different breaker when you go to 220v and you will only have to work in the panel once.

Well, that's a very good idea.

[Hellrazor]

Thats a good idea Don. Its a simple form of a multiwire circuit. Also remember a garage also needs GFCI protection for each circuit. So either GFCI breakers or a gfci outlet wired first in series on each circuit.

[os1kne]

Popular Woodworking did a good article on a configuration just as Don described - it's either in this month or last month. It's really not too hard/complex, but I'd say it's worth a read.

Good luck.

[isddarms]

Thanks! I really appreciate all the ideas. I'm pretty well finished now - just have to see what the real electricians think of my work. They've been kind enough to let me add stuff to the garage under their permit, but were a bit worried about whether I'd mess up their inspection.

[greenacres2]

I suggest you just pull some 12/3 romex. I would go ahead and get a double pole breaker and put in a double outlet box wired with each outlet fixture wired at 110v one on each phase. When you are ready to use 220v all you need to do is turn off the circuits and replace one or both of the 110v outlets with a 220v outlet. This way you will not have to buy a different breaker when you go to 220v and you will only have to work in the panel once.

Okay, it's a 7-8 year old thread, but i'm almost 100% sure that i'm going to run a 240 volt circuit and convert my table saw, RAS and jointer. I'd only ever use one at a time and was searching to see if i could run multiple receps on one circuit when i ran across this. Clever plan--i may even do it so i can run the circuit one weekend and wire the 120 volt--then do the tool conversion at a later date.

edit--make that a 10 year old thread!!

earl

[chopnhack]

Just do your homework well, Earl. Multiwire methods require careful installation to prevent errors that can overload the neutral. There is a good picture to describe what I am thinking:




As you see above, in a shop environment, assuming a 20a breaker on black and red with a shared neutral (12g wire) if you are running large loads on both legs you can potentially have more than 20a running on the neutral line - if these are gfci breakers I think that they might trip, sensing the imbalance.. regardless your neutral line can potentially be overloaded.

MBC's are used all the times in tract homes and can save the builder large $$ but IMHO for small projects that we all get into, its much better to have dedicated runs to several outlets.