Is it ok to tap into dryer 30A line?

[Ken Platt]

Folks - I'm looking to get a nice new big bandsaw as an upgrade for my Jet 14 incher, but some of the ones I'm looking at (say, Laguna 14x14) require a 30 amp 220 circuit, and as my shop is right now, I only have a 20 amp 220 circuit ( which I use for all my big machines, obviously only 1 at a time).

There's this nice big 30 amp dryer outlet just sitting there. We do use the dryer, but not a heck of a lot, and of course would never run both the dryer and anything else. The dryer is right there in my shop, so there's no way that dryer and machine could be accidentally turned on at the same time.

Is there any particular reason (code or otherwise) why I couldn't run another outlet from the dryer circuit, starting at the current receptacle, to take advantage of the 30 amp circuit that's already there?

I tried to look around for an answer online, but wasn't able to find anything clear. It seemed that folks do this, but that it wasn't entirely a great idea, for reasons that weren't clear to me.

And, if this is one of those questions which indicate I just need to call an electrician 'cause I'm clearly a dolt, I have no particular problem with either that conclusion or calling someone.:D The guy who put in the aforementioned 220v 20amp line is local and very reasonable.

Thanks -

Ken

[Wade Lippman]

If it is a 3 wire circuit then extending it is a code violation; any change require upgrading to 4 wire.
If it is already 4 wire, then it could be done, but would be bad practice. What if someone uses the dryer and the bandsaw at the same time. I know you won't, but you could. Bad practice can be interpreted as a code violation.
If they are both in the shop, perhaps you could just have one or the other plugged in.

[Chris Padilla]

Way back before I rewired the garage, I used the dryer outlet to power my table saw. I just used an appropriate extension cord with an appropriate plug to fit the dryer outlet. We have always had a gas dryer so did not need the outlet for an electric dryer. If plugging and unplugging between the dryer and equipment works, you could go that route for now.

It has never been clear to me if one should daisy-chain 240V (and yes, it is 240V these days...not 220V or 230V...just like 110 is actually 120 but I digress), high-amp (like 30) circuits so when I rewired my garage, every 240V/30A outlet is on its own breaker. It seems safer to me to put each on its own breaker so I did. Certainly there are items in our shops that could all be running at once: air-compressor, saw, dust collector. Each of those should be on their own circuit if possible since they will tend to draw a decent amount of current each.

[Mike Henderson]

I don't know code so I can't answer from that point of view. In my shop, I have a couple of 240V 20 amp breakers that I've run two circuits off of in a star arrangement, not a multidrop. They go to two separate machines that I won't be using at the same time and the wire is 12 gauge. If I were to turn the two machines on at the same time, I might exceed 20 amps and the breaker will trip - but neither wire will ever carry more than it's spec'ed for.

You could do the same with a 30 amp breaker, using 10 gauge wire and in my opinion you'd be safe. But I don't know whether that will pass code.

Mike

[The reason I did that is that I ran out of slots in my sub-panel.]

[Jim Becker]

Simplest solution is to make up a cord for the new bandsaw that you can plug into the existing dryer receptacle. This does two things for you...it avoids any reconfiguration of what is supposed to be a dedicated circuit and also insures that you cannot run them both concurrently. A nice 10 gage rubber cord with appropriate connectors will do the trick. For big machines like my bandsaw, I put a pig-tail on the saw so there's no cord to deal with if/when it has to move around and then create a cord of appropriate length to safely reach the receptacle that will power it in use. The pigtail and cord use twist-lock type connectors. The additional benefit to this that you have a physical disconnect right at the saw, too. Yes, this is not the least cost solution sometimes, but it's a good, safe, workable one.

[Mike Cutler]

If you're talking about making some type of an adapter that would plug into the current receptacle, and from there wire out to your saw, then yes you can do that. NEC code stop at the face of that dryer receptacle.
If you want to hard wire in a new receptacle to permanently
Leave the saw plugged in, than it would be highly doubtful it would be a code compliant installation. The dryer , washer, and convenience receptacle in the laundry are generally dedicated circuits.
Make an adapter cord and just plug it when you want to use it.

[Dan Hahr]

I don't know code so I can't answer from that point of view. In my shop, I have a couple of 240V 20 amp breakers that I've run two circuits off of in a star arrangement, not a multidrop. They go to two separate machines that I won't be using at the same time and the wire is 12 gauge. If I were to turn the two machines on at the same time, I might exceed 20 amps and the breaker will trip - but neither wire will ever carry more than it's spec'ed for.

You could do the same with a 30 amp breaker, using 10 gauge wire and in my opinion you'd be safe. But I don't know whether that will pass code.

Mike

[The reason I did that is that I ran out of slots in my sub-panel.]

Mike,

Can you explain what you mean by the star arrangement? I'd like to do the same thing as well with my shop. I can't figure out how you wired it to the panel..

Thanks, Dan

[Ken Platt]

Thanks folks. Making, essentially, a heavy extension cord should be pretty easy. I appreciate the ideas.

Ken

[Mike Chalmers]

If it is a 3 wire circuit then extending it is a code violation; any change require upgrading to 4 wire.
If it is already 4 wire, then it could be done, but would be bad practice. What if someone uses the dryer and the bandsaw at the same time. I know you won't, but you could. Bad practice can be interpreted as a code violation.
If they are both in the shop, perhaps you could just have one or the other plugged in.


The band saw should be three wire, or more appropriately, two wire, as the ground is a given.

[Wade Lippman]

The band saw should be three wire, or more appropriately, two wire, as the ground is a given.

Probably; so ignore the neutral. And while the ground might be a given, 10/2 is called three wire.

[Bill Space]

If it is a 3 wire circuit then extending it is a code violation; any change require upgrading to 4 wire.
If it is already 4 wire, then it could be done, but would be bad practice. What if someone uses the dryer and the bandsaw at the same time. I know you won't, but you could. Bad practice can be interpreted as a code violation.
If they are both in the shop, perhaps you could just have one or the other plugged in.

The three wire VS four wire circuit consideration is important! Good point!

But, as long as the wire coming out of the circuit breaker panel was properly protected by the correct size circuit breaker, and if the bandsaw requires the same type of power feed as the dryer, why would extending the circuit be bad practice? Certainly other circuits in one's home have multiple drops that offer the opportunity to draw more current than the circuit breaker supplying them can provide.

Take a normal outlet circuit that may have a number of 15 amp rated receptacles supplied by a 20 amp circuit breaker. Plug in two 15 amp devices and what happens? The CB trips, just like the drier circuit CB would likely do if the bandsaw and drier were both powered up at the same time.

If it were me I would feel better having a second outlet in the drier circuit. Extension cords offer their own dangers, as does repeatedly plugging in and removing 220 volt high capacity plugs. Not that the capacity matters, as it takes little current to do a person in. But the larger plugs require more effort to remove...perhaps an opportunity for the hand to slip across the prongs...

For sure the NEC should be followed. Do not recall if it addresses this question or if it requires dedicated circuits for appliances such as cloths driers...

Bill

[Wade Lippman]

The three wire VS four wire circuit consideration is important! Good point!

But, as long as the wire coming out of the circuit breaker panel was properly protected by the correct size circuit breaker, and if the bandsaw requires the same type of power feed as the dryer, why would extending the circuit be bad practice? Certainly other circuits in one's home have multiple drops that offer the opportunity to draw more current than the circuit breaker supplying them can provide.

Interesting question, and one that I spent way too much time googling. The best I could find is that Fairfax County VA requires a dedicated circuit for dryers. I suspect it is much more widespread than that, but haven't found a specific NEC requirement.

But even if it isn't, it is still a proper practice, and most (all?) inspectors would consider proper practice to be a code requirement.
A dryer is assumed to require all the circuit capacity, leaving nothing for other appliances. It would be unreasonable for a buyer to have to check that the dryer circuit is dedicated; it is a general condition of habitability. OTOH, normal outlets circuits generally have more than one receptacle on them. I suspect from a legal point of view, a buyer could sue for remediation unless the second outlet was specifically disclosed. The seller could hardly deny they knew about it.

I agree that having to keep plugging and unplugging stuff is bad, but it is just a bad situation that is crying out for a new circuit for the bandsaw.

I hope a real electrician will correct me if I am wrong.:)

[Doug Garson]

Take a normal outlet circuit that may have a number of 15 amp rated receptacles supplied by a 20 amp circuit breaker.
Bill
Wouldn't it be a code violation to have any 15 amp rated receptacles supplied by a 20 amp circuit breaker? I think you meant to say 15 amp breaker (or 20 amp receptacles).

I'm confused by the references to three and four wire circuits. I'm used to a 120 volt circuit being referred to as two wire (hot and neutral ) with the ground assumed unless it feeds a split receptacle which would be referred to as a three wire with two hots, one neutral and again the ground assumed, a 220 circuit would be two wire (both hots on different side of neutral) and assumed ground. Typical wire designation for a 120 volt 15 amp circuit would be NMD 14/2 with a black, a white and uninsulated ground.

[Allan Speers]

Ken, consider using portable cordage for your saw, and then plugging in the dryer only when needed. This would eliminate the need for you to run the new line through conduit or on runners, and give you time to decide if you really "need" an entire new circuit. - Although the latter is a very good idea. It's probably even OK to use 3-wire cordage, although you want to check local codes for that, of course.

Later on, you might also consider adding a sub box in your workshop, in which case running a dedicated 30a line right now would end up being a waste.

[Wade Lippman]

Wouldn't it be a code violation to have any 15 amp rated receptacles supplied by a 20 amp circuit breaker? I think you meant to say 15 amp breaker (or 20 amp receptacles).

I'm confused by the references to three and four wire circuits. I'm used to a 120 volt circuit being referred to as two wire (hot and neutral ) with the ground assumed unless it feeds a split receptacle which would be referred to as a three wire with two hots, one neutral and again the ground assumed, a 220 circuit would be two wire (both hots on different side of neutral) and assumed ground. Typical wire designation for a 120 volt 15 amp circuit would be NMD 14/2 with a black, a white and uninsulated ground.

15a outlets can be used on 20a circuits. The difference between them and 20a outlets is just in the shape of one hole. It is just to prevent you from plugging a 20a load into a 15a circuit.

3 wire means there are three wires in the cable. Couldn't be much simpler.

[Mike Henderson]

3 wire means there are three wires in the cable. Couldn't be much simpler.
Does the wire count include the ground? For example 12/2 is two insulated wires plus ground. 12/3 is three insulated wires plus ground.

Mike

[Doug Garson]

Does the wire count include the ground? For example 12/2 is two insulated wires plus ground. 12/3 is three insulated wires plus ground.

Mike
I agree, are people referring to a 12/3 as a four wire circuit? Yes there are four wires in it but I always thought the wire count only included current carrying wires not grounds. I'm not an electrician I'm just trying to understand.

[Doug Garson]

15a outlets can be used on 20a circuits. The difference between them and 20a outlets is just in the shape of one hole. It is just to prevent you from plugging a 20a load into a 15a circuit

Really? I'm not an electrician but why would it be legal to install a receptacle that's rated for less than the protection device on the circuit? Plugging a 20 amp load into a 15 amp circuit is not dangerous, it will just trip the breaker, however having a receptacle wired into a circuit that is rated for less than the circuit breaker in the circuit is dangerous since the receptacle could be passing more current than it is rated for, and thus overheating, and the circuit breaker wouldn't trip. A quick Google search seems to confirm your comment that a 15 amp and 20 amp receptacle are rated the same internally and either can be used in a 15 amp circuit in the USA but not here in Canada. Seems to me it is poor practice.

[Allan Speers]

Really? I'm not an electrician but why would it be legal to install a receptacle that's rated for less than the protection device on the circuit? Plugging a 20 amp load into a 15 amp circuit is not dangerous, it will just trip the breaker, however having a receptacle wired into a circuit that is rated for less than the circuit breaker in the circuit is dangerous since the receptacle could be passing more current than it is rated for, and thus overheating, and the circuit breaker wouldn't trip. A quick Google search seems to confirm your comment that a 15 amp and 20 amp receptacle are rated the same internally and either can be used in a 15 amp circuit in the USA but not here in Canada. Seems to me it is poor practice.

I dunno about codes, but from a practical, safety standpoint, all that matters is that the breaker matches the gauge of the wiring inside the wall.

[Wade Lippman]

Really? I'm not an electrician but why would it be legal to install a receptacle that's rated for less than the protection device on the circuit? Plugging a 20 amp load into a 15 amp circuit is not dangerous, it will just trip the breaker, however having a receptacle wired into a circuit that is rated for less than the circuit breaker in the circuit is dangerous since the receptacle could be passing more current than it is rated for, and thus overheating, and the circuit breaker wouldn't trip. A quick Google search seems to confirm your comment that a 15 amp and 20 amp receptacle are rated the same internally and either can be used in a 15 amp circuit in the USA but not here in Canada. Seems to me it is poor practice.

It might trip the breaker, it might burn your house down. I would rather not plug a 20a load into a 15a circuit even if you don't think it is dangerous.

If a 15a outlet is the same as a 20a outlet then why would putting a 15a outlet on a 20a circuit be bad practice? What could it possibly harm?
Okay, I had a 18a table saw once with a 20a plug on it, but I think that is the only 20a device I have ever seen; so that is the only time it would matter one iota.

[Wade Lippman]

I dunno about codes, but from a practical, safety standpoint, all that matters is that the breaker matches the gauge of the wiring inside the wall.

That is not at all true. The outlet has to be a match for the breaker and wiring. Both 15a and 20a outlets are matches for 20a breakers; but 30a outlets don't match 20a breakers and 20a outlets don't match 30a breakers. They are code violations and dangerous.

[Allan Speers]

That is not at all true. The outlet has to be a match for the breaker and wiring. Both 15a and 20a outlets are matches for 20a breakers; but 30a outlets don't match 20a breakers and 20a outlets don't match 30a breakers. They are code violations and dangerous.

It's completely true. FROM A SAFETY standpoint, the breaker is there to keep the wall wiring from overheating. Period. If you put a 20 outlet on a 15a circuit and use a 20a appliance, you trip the breaker. If you put a 15a outlet on a 20a circuit, no problem.
I was respondng specifically to a post about mixing 15a and 20 outlets. Of course, even a 30a outlet on a 15a circuit (while stupid) is no danger, as the breaker would still trip before the wiring could get too hot.

What's technically legal is / may be a different matter.

[Frank Pratt]

It's completely true. FROM A SFETY standpoint, the breaker is there to keep the wall wiring from overheating. Period. If you put a 20 outlet on a 15a circuit and use a 20a appliance, you trip the breaker. If you put a 15a outlet on a 20a circuit, no problem.
I was respondng specifically to a post about mixing 15a and 20 outlets. Of course, even a 30a outlet on a 15a circuit (while stupid) is no danger, as the breaker would still trip before the wiring could get too hot.


What's technically legal may be a different matter.


Not quite correct. a 15A outlet on a 20A circuit can be a hazard because the receptacle is only rated to carry 15A, but circuit breaker won't trip until 20A. If a 15A receptacle is carrying 20A for an extended period it will overheat.

[Mike Chalmers]

Not quite correct. a 15A outlet on a 20A circuit can be a hazard because the receptacle is only rated to carry 15A, but circuit breaker won't trip until 20A. If a 15A receptacle is carrying 20A for an extended period it will overheat.


Could be why the 15 and 20 amp receptacles are different. If someone puts a 20 amp appliance on a 15 amp plug, then that is another issue.

[David L Morse]

... a 15A... receptacle is only rated to carry 15A,...

Untrue. According to the NEC a 15A receptacle can be used on a 20A circuit. Thus, to be listed, a 15A receptacle must be as capable of carrying 20A as a 20A receptacle.

It's called a 15A device because it is designed to accept only a 15A plug. The name of something is not always the same as it's "rating".

[Frank Pratt]

Untrue. According to the NEC a 15A receptacle can be used on a 20A circuit. Thus, to be listed, a 15A receptacle must be as capable of carrying 20A as a 20A receptacle.

It's called a 15A device because it is designed to accept only a 15A plug. The name of something is not always the same as it's "rating".

I should have qualified that. In Canada, a 15A receptacle cannot be used on a 20A circuit because it is rated for only 15A. There are 20A t-slot receptacles available that will accept a 15A or 20A plug

[Chris Padilla]

I suspect these little nitpicks could go on for a while in this thread but I think the [OP]'s question has been thoroughly answered....