Electrical Question

[Rink]

Question for you electrical experts:

I currently have a shop, 100 amp service, with numerous 110v and 240v circuits. My table saw is a Delta Unisaw, 5 HP, 240v. I forget the amps.

Soon, I will relocate and be in a rental house with a garage, only 110v outlets.

How can I use my 240v table saw in that garage? I don't want to get my saw motor re-wired.

Although I would be surprised....is it as simple as replacing the standard 110v outlet, if the saw amps are low enough for a 15 amp circuit?

By the way...same situation with my Grizzly 15" planer...

Thanks for any advice.

 

[mjrbuzz]

there are phase converters, but they are not cheap, for the price of one you can likely have a 3 phase outlet installed cheaper, is the breaker panel in the garage?

 

[bobjackson]

The short answer is to rewire the motors for 120 volts. I run the same saw in my garage with 120 and it works great. also my planer runs at 120.

 

[mredburn]

You will probably have to run a new 220 circuit for your saw. Trying to converting a 110 to 220 without changing the Circuit Breaker and wires is not going to work. At least not without a good likelihood of burning the house down. If the main panel is full you may have to add a sub panel or completely upgrade the existing panel. Your existing outlet is probably on a 15amp circuit and has wires to match, your saw is probably rated at 30 amps. You will need a larger wire size to SAFELY wire your table saw.

 

[robertkulp]

Unless I'm mistaken (wouldn't be the first time & certainly won't be the last), the 5HP motor is 240V only and can't be rewired to 120V. It is rated at about 18A for 240V, but if it could be rewired for 120V, it would pull about 36A - much more than a residential 120V circuit handles.

 

[Rink]

Good thoughts so far, thank you. Unfortunately, as it's a rent house...I won't be doing any installation of additional circuits, etc. I may just be stuck without the table saw for a while.

What about a step-up transformer? Anyone have any recommendations on those, or a source?

thanks again.

 

[Edgar]

Good thoughts so far, thank you. Unfortunately, as it's a rent house...I won't be doing any installation of additional circuits, etc. I may just be stuck without the table saw for a while.

What about a step-up transformer? Anyone have any recommendations on those, or a source?

thanks again.

A step-up transformer will not help in this case.
Your 120VAC wiring is probably only rated for 15 Amp.
The transformer will double your voltage, but will halve your current, so you would only get about 7.5A of 240V without tripping the breaker.

 

[Edgar]

If adding a new circuit and rewiring the saw are out of consideration, then I can only think of two alternatives:
1. Do without the saw as long as you are in the house or get a 120V saw
2. Buy a gasoline or propane powered generator to run the saw - you will probably need at least a 7500 watt unit though

 

[glenspens]

look on CL find a 110 saw use untill you get a new place i got a old b&d for $50 works fine for what i do (i don't do much flat work) or pawn shop

 

[SteveG]

If your house has a 220 V circuit for an electric water heater or dryer, you might be able to run a kind of "timeshare" line from either of those circuits. For example, you could unplug the dryer and plug in a fabricated ultra heavy-duty extension cord to provide power to the saw. This is obviously a nonstandard procedure, but can be done safely if done carefully.

 

[lorbay]

An easier way to do this and I have done it for a few friends is to make up an extension cord that plugs into your dryer with a sub panel on the other end with breakers in it the correct size for your table saw and other equipment.

Lin

 

[maxwell_smart007]

No, it's not as simple as changing an outlet. It involves rewiring, and will involve hiring an electrician to run a new 220v circuit to the garage for your table saw.

The 120v circuit runs on one hot, and one neutral (think of it as a push, and a return). A 220v circuit has two hots. As you can imagine, they're hooked up to the panel in very different ways - and they need much different wire sizes.

It's not even theoretically possible to use existing wires...if you have 5hp tools at 220v, you're pulling way too many amps for 120v wires to even remotely handle without bursting into flame...you'd burn the place down.

The solution - and it's much cheaper than hiring an electrician to rewire a rental shop - is to buy some new benchtop 120v tools, and save your industrial tools for when you have a shop that can accomodate them - or pay the electrician to upgrade your rental shop if you're planning on staying for a while.

 

[Edgar]

I'm sorry guys, but I have to respectfully disagree with the solutions offered by SteveG and lorbay.

While this would certainly accomplish the goal of providing 240VAC to the saw, I would never recommend this solution to anyone who is not adequately knowledgeable about electrical wiring. First there is the issue of being able to do this sort of thing safely and second there is the issue of the renter's liability in case any damage was caused to the the house.

 

[plantman]

Rink; A generator is your best and safest way to go !! But it comes with it's own problems. Size, weight, safe use, and cost. Size, at least 8750 Peak watts / 7000 running watts. Weight, they come on wheels for a reason, they are heavy. Safe use, not in an inclosed area or where fumes may enter your home, Cost, 8750. around $600-$800. If you live in an area that power goes out often, need power some distance away from your house, or go camping, this may not be a bad investment. With 5 acres, I can throw my generator in the bucket of my tractor and have power anywhere on the property. Go to a RV center to get the properly rated extension cord. Personaly, I would look for an inexpensive table top saw or used saw to get me by until times change. Rewinding motors can cost you more than you could buy new machnes for, and they won't run on a 15 amp circuit. Also, if you do any tweeking to a rental unit, you are libel for any damage it causes. The 8750 watt generator would give you 2-120 volt 20 Amp duplex outlets, 1-120 volt 20 Amp twist lock outlet, 1-240 volt 30 Amp twist lock outlet, and a 12 volt DC outlet. Requires a 12 volt battery to start. That should about take care of your needs. Even if the power is out, you can run your tools, have lights, and keep your beer cold !!! Jim S

 

[jttheclockman]

So many factors left out again. Who are you renting from??? Is this a family relative??? Where is the panel in the rental located??? Is it in the garage??? How large is the panel in the rental house??? Is there spare room in the panel??? How long are you planning of staying in rental house??? Forget about converting the motor on the saw you have now. Not an option. What are you going to do with your tools when moving??? Do you plan on using these tools much when in the rental and are these projects that can be done using other tools. A lot of woodworking can be done with more than one type tool. A router is a very useful tool. Chop saw and skill saw are good for breaking wood down. Bandsaw also good tool. Are you sure the saw is a 5HP and not a 1.5HP motor???

A generator can be a good option but you have added a cost factor unless you have one. It would be cheaper to find a tabletop saw or a contractors saw. I use a Delta contractors saw and have never run into a situation that it could not handle the work load. Would I love to own a full sized saw, you bet but not needed.

Need to fill in the blanks.

 

[Smitty37]

Question for you electrical experts:

I currently have a shop, 100 amp service, with numerous 110v and 240v circuits. My table saw is a Delta Unisaw, 5 HP, 240v. I forget the amps.

Soon, I will relocate and be in a rental house with a garage, only 110v outlets.

How can I use my 240v table saw in that garage? I don't want to get my saw motor re-wired.

Although I would be surprised....is it as simple as replacing the standard 110v outlet, if the saw amps are low enough for a 15 amp circuit?

By the way...same situation with my Grizzly 15" planer...

Thanks for any advice.

What size breaker do you have it on?

 

[wyone]

If it is truly a 5 HP.. which it MIGHT be if it is a Unisaw.. it could draw as much as 28 amps at 240 volts. That is actually MORE than a dryer. It is equal to a Range or Welder circuit. 28 amps of 240 volt power would require 56 amps of 110 volt power, and such a receptacle is not even made (well ok.. they make them. HIGH PRICED.. SPECIAL APPLICATION..)

Unless you are prepared to spend a lot of money to install the appropriate circuit, I would look for a different saw to use until you can move back to a place that has an appropriate electrical service.

Been an electrician for 40+ years.. do NOT cobble it together.. nothing worse than a house fire.......

 

[Smitty37]

I think Delta says you want #10/3 wire w Ground. and a 40a 220 Delay breaker (I think they say time delay fuse) That makes sense to me...20 amps on each side hence 30 amp wire (#10) is enough but 40 amp protection. You might get away with a 40 amp breaker and #10 wire but If I went to that size breaker I'd probably go to #8 wire.

The time delay is to avoid trips when starting the saw and you can probably get along without it.

If you locate the Planer close enough to the saw you can use the same circuit for both. I have my planer and two saws all plugged into the same outlet...but no two of them EVER run at the same time,

In all of this, you might do well to check the owner/installation manual and if you don't have one you can probably down load one from somewhere on line.

I think I saw someone on here imply that you would draw more current with 220V than 110V --- if I did they got that wrong, you will draw half the current on 220V that you'd draw on 110V.

 

[wyone]

Well actually the current is basically EQUAL on two voltages with the same equipment. It is just split between the two phases. I just did the quick DESIGN amperage, which is how we size the circuit and according to the National Electrical Code 28 amps at 240 volts. Each of the two phases would carry 28 amps. If the same motor was installed using 120 volts that one phase would carry 56 amps.

As a MOTOR we are allowed some things different than if the circuit was other types of load. You are absolutely correct about the 40 amp circuit breaker for the load. typically we would only be allowed to use a 30 amp breaker on the #10 wire on a normal circuit. But as a motor, it is not uncommon for the starting current of the motor to be 5-7 times the actual running load of the motor. The higher current breaker will typically allow the motor to start and run.

 

[Smitty37]

Well actually the current is basically EQUAL on two voltages with the same equipment. It is just split between the two phases. I just did the quick DESIGN amperage, which is how we size the circuit and according to the National Electrical Code 28 amps at 240 volts. Each of the two phases would carry 28 amps. If the same motor was installed using 120 volts that one phase would carry 56 amps.

As a MOTOR we are allowed some things different than if the circuit was other types of load. You are absolutely correct about the 40 amp circuit breaker for the load. typically we would only be allowed to use a 30 amp breaker on the #10 wire on a normal circuit. But as a motor, it is not uncommon for the starting current of the motor to be 5-7 times the actual running load of the motor. The higher current breaker will typically allow the motor to start and run.

I have a 35a 220 breaker on my AC with #10 wiring....it passed electrical code in 2005 when the house was built.

 

[wyone]

The AC falls under similar rules for breaker sizing since it is a motor. I think the most difficult portion of that installation you describe would be FINDING the 35 amp breaker. LOL.. still would most likely be allowed, depending upon the actual amperage of the equipment.

 

[Rink]

Thank you, everyone, for the suggestions. And for the electrical engineering lesson! I have done some electrical work, but all very simple, nothing as involved as this would take. I appreciate the education, some very interesting things to learn.

As I mentioned, since we'll be renting, it seems my best option is an inexpensive small table saw or band saw for the time being. When I get to my next "permanent" place, I can break out the 240v Delta Unisaw again.

thanks again.

 

[maxwell_smart007]

Thank you, everyone, for the suggestions. And for the electrical engineering lesson! I have done some electrical work, but all very simple, nothing as involved as this would take. I appreciate the education, some very interesting things to learn.

As I mentioned, since we'll be renting, it seems my best option is an inexpensive small table saw or band saw for the time being. When I get to my next "permanent" place, I can break out the 240v Delta Unisaw again.

thanks again.

Good choice!

 

[ALA]

Probably a long shot but you might find a used 120 V motor and swap them out. I'm sure a new motor would be too costly.