That reasoning works the other way also, holiday time with most or all burners on and it probally would trip.
Dryer and Range on same circuit
- Thread starter Sharpie
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That reasoning works the other way also, holiday time with most or all burners on and it probally would trip.
Volta
Senior Member
- Location
- Columbus, Ohio
220.14(A). Dryer outlet~5000W, Range outlet~8000W.
220.18 The total load shall not exceed the rating of the branch circuit ...
5000+8000=13000. 13000/240=54A circuit needed.
210.21(B)(3). A 30 amp receptacle not allowed on a 50 amp circuit.
Can't do it.
- Location
- Connecticut
- Occupation
- Engineer
Volta, where do you see in 220.14(A) that a dryer outlet is 5000W and a range outlet is 8000W? I don't see that. I see that loads for dryers and household cooking appliances shall be permitted to be as specified in 220.54 and 220.55 (220.14(B)).
220.54 does say a dryer shall be calculated at not less than 5000W (but to use the nameplate if it is higher than 5000W.) Per 220.55, you can use the nameplate rating of the range, OR use the demand factors in table 220.55.
If the nameplate of the range is 2500W, and you use the 80% demand factor in column A, then the range demand is 2000W.
2000W+5000W=7000W which is 29.17A. That would be allowed on a 30A circuit.
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
Care to tell us where we can get a range that only needs 2500 ?
- Location
- Connecticut
- Occupation
- Engineer
No idea. Don't know if any such thing exists. But the code gives guidelines for electric cooking appliances over 1-3/4kW Rating, in section 220.55. Code does NOT say that ranges must be figured at 8000W.
The OP doesn't give the ratings of the proposed range. But as I mentioned earlier, a range up to 2750W would be allowable on the same 30A (240V) branch circuit as a 5000W (or smaller) dryer.
Volta
Senior Member
- Location
- Columbus, Ohio
First, remember that branch-circuit calcs are referenced in Part II of Article 220, and feeder and service calcs are Part III, generally.
A dryer outlet load on a feeder will be at least 5000 W, for now let's use that for the branch-circuit load too.
For the range, as you said, 220.14(B) permits us to use 220.55. Note 4. allows us to use the table for a branch-circuit for one range. That might stop it right there, as your proposed circuit is more than one range.
The OP said a range, and no nameplate info was given. T220.54 requires us to use Column C, unless permitted in Note 3. That may stop you again.
But lets say you can find a range that is rated only 2500 W. It would need to come with a 30 amp plug on it to work with 210.21(B)(3). That is not what we think of when somone says "a range", and an everyday "range receptacle" won't work here, it would have to be a second "dryer receptacle".
growler
Senior Member
- Location
- Atlanta,GA
I can answer that one. The house does belong to the owner. But any installation of electrical is the responsibility of the electrical contractor. The EC must provide warranty and accept liability for the work performed.
I don't let anyone tell me what type of work I'm going to be responsibile for. The code is a minimum safety standard and this would be safe but it's a darn poor circuit design.
Believe me the customer is not going to accept responsibility for the crappy work, they are going to tell all the neighbors about the breaker that keeps tripping and the electrician that installed it.
If you don't feel comfortable with a job it's always better to walk and let them get someone else. I would rather be known as a hard ass than a dumb ass. You do work your way and then you stand behind it.
- Location
- Connecticut
- Occupation
- Engineer
No, the circuit I propose has only one range.
Note 3 says for over 1-3/4kW thru 8-3/4kW, IN LIEU of Column C you can use column A or column B as described. 2.5kW falls into this range of values.
For all I know, this mystery 2500W range would come with a 30A plug on it. Nowhere does the code say a range must be plugged into an "everyday range receptacle." Maybe the range could be hardwired, if it was in sight of the panel, so that the branch c/b served as the disconnecting means. Just because the word "range" is used, that doesn't automatically mean 40A branch circuit and everyday "range receptacle."
- Location
- Connecticut
- Occupation
- Engineer
What would be "poor" circuit design about adding load to an existing circuit, if that added load does not exceed the circuit rating?
The work would only be "crappy" if you installed it crappily. Why would the breaker be tripping if the load doesn't exceed the circuit rating?
Volta
Senior Member
- Location
- Columbus, Ohio
No, it has an outlet for one range and an outlet for one dryer.
Yes, it does. And if that is what we have that is one thing. But if a person says "a range", they are not automatically planning to order a small custom range.
I agree. If it all works, that is fine. I have no moral judgement in this discussion. This is an NEC forum thread, either it can meet code, or it can't.
But from the information provided in the OP, what was proposed, interpreted using reasonable assumptions, would meet neither the intent nor the letter of the NEC, IMO.
Using other assumptions, anything is possible.
- Location
- Connecticut
- Occupation
- Engineer
Read the rest of note 4. If you have one range, use T220.55 as is. If you have one counter-mounted cooking unit and not more than two wall mounted ovens, add the nameplates of the units and treat the total as "one range." Note 4 does not infer an individual branch circuit for a range in order for T220.55 to apply.
Of course not. Nor are they automatically planning to order a standard range.
Yes, the point is that if it meets code, then the installation would be acceptable.
Based on the information provide in the OP, however, I don't believe that your assumptions are "reasonable." The OP asked said he reviewed section 210 and didn't see any code restrictions. It is then reasonable to assume that he wasn't being asked to install a 40A receptacle on a 30A circuit, in violation of 210.21(B)(3). Or he may have looked at 210.19(A)(3) and seen that ranges of 8-3/4kW or more (like standard ranges) shall have a minimum branch circuit rating of 40A. So it is reasonable to assume that the "range" in question is smaller than a "standard" range.
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growler
Senior Member
- Location
- Atlanta,GA
Sure it could work and even possibly win a "Rube Goldberg" award.
The best thing for a home design is the simplest, most efficient and most cost effect design. Never make things more complicated than they need to be. It doesn't get any more simple than a circuit for the dryer and a circuit for the range. They can work for the next fifty years because there are no moving parts to fail. A contactor has contacts, coil and control wiring that can also fail at some future time and now the circuit is more complicated to trouble-shoot and repair. Most service electricians are not going to have these parts on the sevice truck because this is not a standard repair.
Jim W in Tampa
Senior Member
- Location
- Tampa Florida
I see this install as having many unanswed questions that need looked at before it can be either a yes or no
#1 is this dryer outlet a 3 or 4 wire circuit
if it is 3 wire then stop because your installing a new outlet and it will require a grounding conductor as well as grounded.
#2 what is the size of new range ?
#3 can the circuit carry the full load of dryer and range at same time. If not then there is a problem.
Even if you somehow can fit the 2 loads on that 30 amp i suspect the breaker will be triping often. Now you have the customer complaining and that could end up in court and issues with your license. Neither one win or loose is not good and will cost you in time, money and bad name for your company. Most here will agree that its very poor design even if legal.
What will you do if they show up with a normal full size range ? Your setting yourself up for bad day.
I personally would tell customer the problems it causes and refuse to do it. Others can do as they like.
#1 is this dryer outlet a 3 or 4 wire circuit
if it is 3 wire then stop because your installing a new outlet and it will require a grounding conductor as well as grounded.
#2 what is the size of new range ?
#3 can the circuit carry the full load of dryer and range at same time. If not then there is a problem.
Even if you somehow can fit the 2 loads on that 30 amp i suspect the breaker will be triping often. Now you have the customer complaining and that could end up in court and issues with your license. Neither one win or loose is not good and will cost you in time, money and bad name for your company. Most here will agree that its very poor design even if legal.
What will you do if they show up with a normal full size range ? Your setting yourself up for bad day.
I personally would tell customer the problems it causes and refuse to do it. Others can do as they like.
And a very safe assumption as I have NEVER seen an electric clothes dryer that draws less than 20-25 amps per leg and that would not leave any room for anything other than a very small hotplate to be added on without the breaker tripping. :grin: (And before any smarty-pants chime in, remember we're NOT talking about a gas dryer here.)
There are certain situations where even without nameplate data it is not a stretch to figure out what's gonna happen. :roll:
The fair was fun BTW, got five more weekends to go.
Reading through the thread so far, seems the consensus is that the OP's proposed install might not be a Code violation (unless the current dryer circuit is 3-wire) but it is NOT a good design practice or one which most would be comfortable with.
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growler
Senior Member
- Location
- Atlanta,GA
Folks you might find a range and a dryer that this circuit would work for but it's not a normal situation. How long do appliances last anyway? Just as soon as one of these appliances goes bad the customer will be out shopping for a new one without a care in the world about current draw.
They bring home the new dryer or range and then there is a problem. And then it happpens, "that electrician screwed me". The next electrician comes in and looks at what's been done and says "What a hack", and thus comfirmed that the customer has been screwed.
Thanks everyone.
This thread has gone a lot longer than I expected!
The HO is being cheap. They want me to come and look it. They don't have the new stove yet (they are looking on Craig's list). I agree with the majority of what I've seen here that it may or may not be code compliant, however it is most likely a bad design for the home owner.
The walls are paneling and the ceiling is stapled up acoustical tiles. They don't want these things touched so I told them "rough estimate (without driving 1 hr each way to see it) to run wiremold around the room with new circuit would be approx. $500. They almost choked. At that moment I was determined not to do this work.
I'm not starving, and I don't think that I want to take on this headache.
This thread has gone a lot longer than I expected!
The HO is being cheap. They want me to come and look it. They don't have the new stove yet (they are looking on Craig's list). I agree with the majority of what I've seen here that it may or may not be code compliant, however it is most likely a bad design for the home owner.
The walls are paneling and the ceiling is stapled up acoustical tiles. They don't want these things touched so I told them "rough estimate (without driving 1 hr each way to see it) to run wiremold around the room with new circuit would be approx. $500. They almost choked. At that moment I was determined not to do this work.
I'm not starving, and I don't think that I want to take on this headache.
Look at 210.23. Stop making assumptions and read the code. Remember that the code is only concerned with safety - not convenience, adequacy, or even cost. Tripping a circuit breaker is not considered a safety issue. The question is, can this installation be code compliant. The answer is maybe, but we need more information. 210.23 (B) says that a 30-amp branch circuit may be used for cord and plug connected utilization equipment as long as it does not load the circuit to more than 80% of it's capacity. 30 amps times 240 volts = 7200 watts. 80% of 7200 watts is 5760 watts. Assuming that the dryer is the standard 5000 watt unit, it is OK. If the new range does not calculate to more than 5760 watts (see note 4 to table 220.55 - nameplate could be 7200 watts) the range would be OK. Also see table 210.24 - since this is now a multioutlet branch circuit the range receptacle would be required to be 30 amp not 50-amp. The fact that the breaker would trip if both appliances are used simultaneously does not appear to be a code issue, but rather a design issue; so if the homeowner is willing to make that sacrifice to save money, it is their choice. Also remember that if the range that they purchase off of "Craig's list" is rated 8.75 kw or more then a 40-amp circuit IS REQUIRED - see 220.19(3). Bottom line, if you carefully size the new range, it is possible. Perhaps a gas range should be suggested.
Volta
Senior Member
- Location
- Columbus, Ohio
Sure it is, otherwise we would not need any load calculations. We rely on math first, and protection from devices second. The conductors, terminations, and other components would quickly become damaged by repeated overheating if we simply wired loads to the tripping point.
No, an additional 5760 watts are not ok, the total load shall not exceed the rating of the branch-circuit. 220.18.
Branch-circuit conductors supplying household ranges, wall-mounted ovens ...shall have an ampacity not less than the rating of the branch circuit and not less than the maximum load to be served. 210.19(A)(3).
No conductor shall be used in such a manner that its operating temperature exceeds that designated for the type of insulated conductor involved... 310.10.
I agree, but 5760 watts is not a result of careful sizing.
Probably.
- Location
- Massachusetts
If it is a safety concern why can I place multiple receptacles on a circuit?
Volta
Senior Member
- Location
- Columbus, Ohio
Permissive code :roll:.
What we cannot do is design a circuit which is planned to exceed its capacity.
I can run a circuit with fourty NEMA 14-30 receptacles on it so the dryer can be moved around.
I cannot design a circuit with two 14-30 outlets intended to serve more than a total of 7200 watts.
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