i have intercepted the 220 line to my dryer, installed a j box and am running a 220 line from there for my tablesaw(cabinet) ..i consider these as givens
dryer and table saw will never be run simultaneously
goes against electrical code(?)
potential insurance issues, even if this modification had nothing to do with a fire
all that being said is there actually anything dangerous with this set up… thank you very much for any and all advice…
jpa
addendum…
what i meant by “givens” above, im saying for the sake of an argument lets accept this as the way it is or will be…
the saw is a powermatic 66. 3 hp-1 phase, 15 amp. the wire from the main panel to the j box is 10/3, approx 5′ long and buried in wall. the j box is surface mounted in garage.dryer feed is 10/3, and is run through conduit…surface mounted…the feed for the tablesaw is 10/3.it is also running through conduit(approx 45′) according to manual, a 10 ga wire running from a 30 amp breaker is needed??? but who really knows?
regardless, i have not made any connections( to the j box) … i appreciate everyone’s opinion, and hope to hear from more. i think a licensed electrician will be getting a call in the near future.
Edited 2/4/2003 4:53:18 PM ET by jpa
Replies
The only problem that I know you could have is if you have extended that line too far.
If you are putting a 20' extension or more on that connection it is possible that you could be trying to draw too many amps and heating up the wire in the wall. This would be a very bad thing. But also realize that your not running the tablesaw for long periods of time like a dryer would.
One additional question that you need to understand. Is the wire in the walls of the house copper? In the mid 70's some homes had aluminum wireing installed. Aluminum wireing is a very bad thing if not regularly maintained. Worse than just aluminum is mixing aluminum and copper together (takeing an aluminum wire and putting a copper wire with it in a single twist nut) the expansion and contaction rates of the two metals is very diferent and the connection will loosen over time.
So to sum this up you need to be able to answer a few more questions and then it "depends" on your situation. My guess is that your alright!
>> dryer and table saw will never be run simultaneously
why not? - I don't think this is a good "given". The result if they are run simultaneously: you'll possibly overload the circuit tripping the breaker.
A couple of potential problems / issues that occur to me that you may wish to consider:
Either: Don't run a smaller wire to your saw than that which feeds your dryer. What size is the breaker to the dryer? Mine's 30 amp with probably #10 wire (what it should be for 30 amp). The wire is that size because that's what it needs to be for the 30 amp current draw. The 30 amp breaker is there to protect the house and the wire in the event that more than 30 amps are drawn on that circuit. On a dedicated circuit, your saw will only require a 20 amp (technically 15 amp - I'd put 20 amp) breaker and #12 copper wire. The #12 wire is too small for more than 20 amps. If you run #12 or #14 wire to your saw off of your existing 30 amp breaker, that wire is not adequately protected by that large of a breaker and could overheat causing you safety issues and risk of fire.
Or: Run the number 12 wire and install an additional breaker where you tapped into the dryer outlet and the saw. Check your electrical supplier for a small breaker / fuse protected box / disconnect. The wire between the dryer outlet and the disconnect still needs to be sized according to the size of the breaker for the dryer.
Length of wire run is also a factor. Long runs need to be upsized to provide adequate power to your tools, or you're likely to burn up your motors more quickly - this won't be immediately evident but takes a while and is less of a problem for a 220 volt circuit. Long runs have a voltage drop. Quoting the following interesting read, "Operating a motor at low voltage causes the torque to drop and the motor to heat up (shortening the life of the motor)." http://www.popularwoodworking.com/features/fea.asp?id=1090
As a rule of thumb you can use the following wire sizes. Long and very short runs may vary.
15 amp circuit - #14 wire
20 amp circuit - #12 wire
30 amp circuit - #10 wire
40 amp circuit - #8 wire
50 amp circuit - #6 wire
Edit - I now see you have a cabinet saw. Is that 3 HP? What's the amp rating for that saw? My 1.5 HP contractor's saw is about 8.5 amps at 220 volts. Yours should be something like twice that, huh? The above was written with a 1.5 HP saw in mind. Make sure you size that wire for your amperage draw.
best of luck,
jdg
Edited 2/4/2003 10:43:22 AM ET by jdg
Edited 2/4/2003 10:48:06 AM ET by jdg
Edited 2/4/2003 10:54:34 AM ET by jdg
Edited 2/4/2003 10:57:51 AM ET by jdg
Just out of curiosity, what make/model saw is it, what hp, and what does the UL tag say about amps or watts, and are there any requirements on the tag or in the manual for max and/or min circuit ampacity.
Oh, yeah, if it has a cord and plug, what does the plug look like (maybe like this -.- ?).
Edit: p.s. There are a half-dozen or so electricians who are frequent posters next door on Breaktime, so you may want to ask over there for more responses.
Be seeing you...
Edited 2/4/2003 10:55:41 AM ET by Tom Kanzler
Hey j, I took three and a half years out of my fulltime woodworking for a stint as the County Building Inspector here in Southwest Virginia, so I can tell you a little about what you are doing. At the onset I will say that it is ok to do what you did if you had enough wire to connect them safely. I mean not just a couple of twists and some black tape. It is ok to use junction boxes to connect wires in and run to other places, but the code does require the box to be accessable. Not patched under the sheetrock in the living room and accessable by anyone who remembers where it is and can wield a knife. It has to be readily accessable ie just take the cover off. I think the main thing you need to be sure of is if you use the right wire (size) for the size of the breaker in your main box where the dryer wire oridginated from. I would figure they ran a no.10 wire, and if it was within the last few years,(after '97)it should have been 10/3 with a ground, and it should have a 30 amp breaker protecting it. You just have to make sure that if it has a 30 amp breaker you do not use smaller wire than #10 in the circuit. That means you need to have used at least #10 from you j/b to the saw.
Your idea that the loads won't be used at the same time is reasonable and all and while I have been back in the workshop for almost three years and have lost some of the (use it or loose it) N.E.C. stuf I had to learn to pass the inspector test and do the job, I only remember one exclusion from other loads to a laundry room and that is for the required 20 amp laundry circuit. I'm pretty sure they don't fool with you on the 220 for the dryer, probly since it isn't required that you have a dryer anyway. And since you can have a 20 amp circuit with moore outlets that would ever be used and you don't have to take into account the max load you could put on a circuit if you plugged in two things into each with twenty amps each for every outlet you have made out ok on you asumption.
I know I may be opening myself up to pretty hard scrutiny from other B.I.s , engeneers, and spellers, but that's my take on your situation. Be careful when the saw is plugged in no matter where you get the juice. I think you have more danger from the blade than anywhere else in your design. A.T.
I'm going to disagree with some of the others.
In my opinion, you've violated code. The dryer circuit should be dedicated and not have a saw on it.
I also don't think you can run your saw on a 30 amp circuit even if you use #10 wire.
Lastly, you clearly didn't get a permit and this is an issue for later resale of the home, but, more importantly, for insurance reasons. If you have a fire or an accident, the insurance guys are going to find a non-code situation and they'll walk away from any and all claims.
RECOMMENDATION: At least get a building permit, have the work inspected, and know that what you've done is code and legal. I think you'll be in for a surprise and you'll have to run a completely new circuit.
John
>>I also don't think you can run your saw on a 30 amp circuit even if you use #10 wire.
Why? The two 240 volt circuits into my shop are #10 wire and on a 30 amp breaker with 30 amp receptacles. All were installed by a licenced electrician and approved by the building inspector. The tools that run off them are using 10 amps maximum (except on start up). The tool plugs are 30 amp going into 30 amp receptacles with motor to plug wires being 14AWG.
The breaker is properly sized to protect the wiring to the receptacle and the receptacle does not exceed the capacity of the circuit which is the intent of the code. It's not the breaker function to protect anything beyond the receptacle AFAIK.
You may be right, but I get nervous when things are "non-standard". In your case, the wire from the saw to the outlet is 14 gauge. To pop the breaker, you'd have to pull more than 30 amps, which could overheat the 14 gauge wire and cause a fire.
I personally would change the 30 amp breaker to 15 amps so that the 14 gauge wire from the saw to the receptacle was protected as well. Maybe not required by code but, IMO, safer.
In the case of this post I was assuming that the poster didn't install a 30 amp receptacle or perhaps didn't run #10 wire.
In any event, I still don't think what was done here meets code and in any event there should have been a permit and an inspection.
And it's pure nonsense to assert that the two devices will "never" be run at the same time. If something can (physically) happen ... it will happen.
John
I agree with John on the size of the circuit. It is too big for the tool(s). I run a Unisaw off a 20 amp 220 circuit since the motor is rated at 17amps. This is plenty. By using a circuit to large for the tool, you are risking a fire hazard should something occur between the tool and the outlet that isn't big enough to pop the breaker but too much for the tool/tool cord to handle. This may not be as big a deal with your PW if you use large guage cord and assuming the saw has an on-board breaker for the motor. My concern would be with the smaller corded tools. Using 20 amp outlets for tools designed for 15 amp service is more than enough. If you feel the need to use 30 amp circuits for your smaller tools, I would recommend running multiple 20 amp circuits. Bigger isn't always better when wiring circuits. Its better (safer) to appropriately match the circuit to the tools that will be pluged into it.
--Rob
Rob, a dead short--which is what a circuit breaker is intended to protect from--in the motor or it's wiring will pop the breaker immediately. Think about a single 100 watt bulb going into an otherwise unused 20 amp residential circuit or a 1/4hp grinder motor going into the same circuit.
I have to disagree with the gentlemen saying the wire is too large.
I think countless times I've used a 1.5 amp item on a 20 amp circuit, or a 5 amp drill, or what ever.
jdg
I'm not sure this is a fair comparison.
Let me give you an example from my own "shop". I've got a Performax 16-32 sander that is 110 volts. If I plug it into a certain 15 amp circuit (dedicated), and do some heavy abrasive planing, the motor will lug for awhile and then pop the breaker. The motor in this case is very hot to the touch, and the wire from the motor to the outlet is "warm". I also know by way of example that this motor has its own limit switch that will trip by itself.
Now, let's assume the motor doesn't have the limit switch. Let's also assume I change the breaker to 20 amps (instead of 15). I also install a 20 amp receptacle. I continue to abrasive plane, and now I'm really stressing the motor which really starts to overheat and bog down. But the breaker doesn't trip. The cord gets hot. The breaker doesn't trip. Things get hot enough for a fire. Is this possible? You bet.
If the original poster is bound and determined to proceed, here is what I'd recommend:
1. Replace the original 30 amp breaker with a 50 amp breaker and run the appropriate sized wire to the current J-box.
2. Replace the J-box with a mini-panel which contains a 30 amp breaker for the dryer and a 20 amp breaker for the saw (both 220 volts).
3. Use the current 10 gauge wire from the J-box (to be a new subpanel) to the receptacle for the saw. This is more than required but the 45 foot length may get voltage drop, and the oversized wire will prevent that.
4. Install a 20 amp receptacle for the saw.
5. Replace the 14 gauge wire from the motor with a 12 gauge wire so that this can carry the extra current.
6. Done.
As an aside, you could instead run a new, 20 amp 220 volt circuit from the breaker panel to the saw. I'd do one or the other. What I *would not do* is use the same 30 amp breaker for both devices. I'm absolutely certain this is a code violation. The code has provision for dedicated motors that are more than 1 (1.5?) HP and requires that they be on separate circuits.
I'd also get a permit and have all of this inspected.
John
Here's a post from Breaktime where I asked if this was code:
http://forums.taunton.com/tp-breaktime/messages?msg=27274.4
Note that the gist of the reply is that you cann't mix the dryer and saw "circuits" on one breaker, and the 30 amp breaker is too large for the saw.
John
"Now, let's assume the motor doesn't have the limit switch"
Sorry, but you have no idea of what you are talking about.
A limit switch is a switch that operates when something moves to a set limit. What you are talking about is overload protection.
If the motor does not have overload protection then that needs to be added at the motor controller. There are various types of approved overload protection. In general the brach circuit circuit breaker is not the overload protection. In most cases it is either internal thermal protection or over current protection in the motor starter.
The branch circuit circuit breaker is designed to protect against faults in the wire and recptacle. It IS NOT DESIGNED TO PROTECT THE LOAD.
In fact the code specifies that a 3 hp, 230 volt motor has a full load current of 17 amps. That requires a minium circuit of 25 amps, but 30 is the next most common size.
In fact because of large starting currents the in some motor applications the code allows you to put in an even larger breaker than would normally be allowed by the size of the branch circuit wire.
Geez, I'm sorry I used the wrong term. By "limit", I did mean "overload protection".
I don't know how you come up with a 30 amp circuit as appropriate for a 3 hp saw. That's way, way too big. I haven't figured the amperage of the saw in particular, but if you're right about 25 amps, that would be 12.5 amps per hot leg. A 20 amp 220 volt circuit would handle that just fine.
John
There is no such thing as a circuit being too big. Any electrical device will use only the amount of current it needs. If I plug a 110v .05A diode into a 10A, 20A or 30A circuit it will still only use .05A. Circuits are designed to protect the wiring, not the load. If your sander pops the breaker on a 15A circuit it either requires more than 15A to operate or there is something wrong with it. If moving it to a 20A circuit fixes the problem then it must require that much to operate. Moving it to a 30A circuit would be overkill but would not do any harm to the device or the home.Tom
The problem is not that you used the wrong term. The problem is that you don't know anything about electrical wiring and motors!
"I don't know how you come up with a 30 amp circuit as appropriate for a 3 hp saw. That's way, way too big. I haven't figured the amperage of the saw in particular, but if you're right about 25 amps, that would be 12.5 amps per hot leg. A 20 amp 220 volt circuit would handle that just fine."
When I said 25 amps I ment 25 amps. That is 25 amps on a 240 volt circuit. EACH HOT LEG WILL HAVE NEED TO BE RATED FOR 25 AMPS.
Check here for a table showing the size of the breakers and wiring for motor branch circuits.
http://ecatalog.squared.com/catalog/html/sections/06/17206028.htm
Look down the column for One Phase, 230 volts until you get to the 3 hp row.
YOU WILL SEE THAT IT SHOWS A 30 AMP CIRCUIT BREAKER AND A ***MINIMUM*** OF #12 WIRE.
Bill,
I'm an ex-general contractor and I've done lots and lots of residential wiring. I've never had an inspector kick back any wiring I've done. Period.
I got involved in this thread because the original poster had done things that are clearly against the NEC. I was trying to help out.
How can I say this? Stuff it.
John
Now boys..... Be sweet.
I conceed Bill that you may have a point. I wonder whats up with that sander. Perhaps your brushes are shot. What size is the wire on that circuit and how long is it. What's the name plate rating? I think if it's tripping your breaker or getting hot enough to approach being a fire hazard, it's time to consider a) looking further into potential problems; b) servicing the sander; c) pitching it.
jdg
Edit: Should have been sent to John. Sorry Bill
Edited 2/4/2003 10:46:26 PM ET by jdg
John,
>> If I plug it into a certain 15 amp circuit (dedicated)
I'm wondering also about this circuit - You say a "certain" circuit. If the nameplate rating on that tool is less than 15 amps, theres a couple of possibilities that occur to me.
1) There's low voltage - due to maybe high resistance - on that circuit for some reason, resulting in a higher amperage draw. - I'm not certain of the logic of this statement, but it's my understanding of how it works.
2) There's a problem within the tool or it's power cord that causes it's amperage draw to exceed it's nameplate rating.
jdg
I think you're probably right. Another possibility is a flawed breaker (too sensitive). The sander runs without tripping the 15 amp breaker when my now have my shop. I suspect the breaker or, perhaps, nicked wire. When I get the time (you know how that goes ...) I'll check for the nicked wire, and then probably simply replace the breaker.
The overload protection on the motor of the sander kicks in now when the motor is "done", rather than tripping the breaker.
John
Since you're getting all this great feedback, would you perhaps do me a small favor? Would you read the motor catalog number off the nameplate and post it here? It's near the bottom of the nameplate. The spec number would be nice, too. It's at the top. I'm curious what motor PM is using on those saws.
Thanks.
Edit: p.s. While you're under there, what's the frame size?
Be seeing you...
Edited 2/4/2003 2:14:39 PM ET by Tom Kanzler
Not going to address the code issues, I'd have to ask myself. My poor memory says you'd have trouble selling this. but I also remember exceptions for two pieces of 220 equipment being ran on the same circuit if they are unlikely to be ran at the same time.
Personally, I'd hesitate to do this. If at all possible I'd add a seperate circuit. But if not, I'd be more likely to put in a small subpanel where you put the j-box with 2 breakers one 30 amp for the dryer and one 15 or 20 amp for the saw.
If this isn't possible, then I'd insure the cord from the wall, and the plug, to the saw is capable of 30 amps and put a fuse or breaker box on the side of the saw with 15 or 20 amp fuse or breaker protection for the motor itself.
Somehow it seems for fire safety you must protect the entire system so no part that isn't rated for 30 amps of current can ever see 30 amps of current. Anything less is asking for trouble in my view.
jpa -
A dryer must be on a dedicated circuit (per code) but you seem to indicate that code issues aren't a concern for you.
Your saw is overprotected with a 30A breaker. Yes, a dead short will trip the breaker no matter what its amperage rating. But the saw motor should, by rights, be protected with a minimum size of breaker as listed on the motor name plate.
You can operate more than one 220/240v device on a given circuit however you need to be sure no two devices will be operated simulataneouly. Do you expect your wife, assuming she does the laundry, or anyone else in your household for that matter, to come to your shop and let you know when they're going to run the dryer? Can you hear the dryer running in your shop so you'll know not to start your saw until it shuts down?
If you have the capacity in your existing panel, I think you'd be much better off to hire a qualified electrician to either wire in a dedicated outlet for the saw or perhaps install a new subpanel with a little expansion capabilities for future use.
I know you can run multiple 220v machines off a single breaker since I just this morning went over the electrical design for the shop I hope to build later this year. I explained that the lathe, table saw and jointer would not be used at the same time since this is a one-person shop. He agreed that these machines could be 'daisy-chained' on one circuit.
Dennis in Bellevue WA
[email protected]
Something that's been bugging me is if there is only 5' from panel to J-box, and conduit the rest of the way, why didn't you just run another 10/3/G into the J-box, and pull new wire into the conduit (use the old to pull the new bundle)? Then you'd have separate circuits for each. You've only got 5 current carrying conductors, three of which are dropped off at the dryer. Just a thought.
Be seeing you...
This is clearly the only answer to the situation. And it's cheap. And, lastly, will only take a few minutes. All he has to do is run two #10 wires to the J-box and install another 30 amp breaker in the panel. He may or may not need to run another ground wire.
John
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