- Location
- New Jersey
- Occupation
- Journeyman Electrician
A 12 amp dishwasher fastened in place and a 7 amp disposal fastened in place cannot be on one 20 amp circuit?
Dish & Garb Together
- Thread starter tryinghard
- Start date
- Status
A 12 amp dishwasher fastened in place and a 7 amp disposal fastened in place cannot be on one 20 amp circuit?
electricmanscott
Senior Member
- Location
- Boston, MA
More proof that the NEC is based on overkill. This setup would never be a problem.
tryinghard
Senior Member
- Location
- California
No Article 240 is for the overcurrent protection (breaker), I am at 430.24 for the circuit conductors; this coupled with Art 334 and 60 deg column in 310.16 qualifies the 12-2 romex.
The breaker cannot be over 20A as you noted; but it can be qualified through 430.52 & 53 as 9.8A + 9A = 18.8A meaning a 20A breaker could suffice "where it can be determined...[it] will not open under the most severe normal conditions of service that might be encountered" (430.53(B)).
I have ALWAYS ran 2 20amp circuits, one for the disposal and one for the dishwasher, usually a 12-3 to the disposal outlet and then ran a whip to the dishwasher.
I did it because #1. it was our comany policy and #2. as time goes on each of these appliances, in their prospective evolutions, always end up drawing more power. Now the big thing in dishwashers is disposals, and separate heating elements.
Trust me, you don't want to insall one circuit and then have a service call because the breaker keeps tripping. I have had to fish a circiut in one or two times in that area of the house and it is a pain in the neck.
Maybe and only maybe would I ever consider running (in new construction) a single 20 amp circuit for both. I would NEVER run only a 15amp for both. You are asking for trouble if you ask me.
I did it because #1. it was our comany policy and #2. as time goes on each of these appliances, in their prospective evolutions, always end up drawing more power. Now the big thing in dishwashers is disposals, and separate heating elements.
Trust me, you don't want to insall one circuit and then have a service call because the breaker keeps tripping. I have had to fish a circiut in one or two times in that area of the house and it is a pain in the neck.
Maybe and only maybe would I ever consider running (in new construction) a single 20 amp circuit for both. I would NEVER run only a 15amp for both. You are asking for trouble if you ask me.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
I'm unable to find the NEC violation. Help!
tryinghard
Senior Member
- Location
- California
The circuit rating noted in 422.10(B) does lead to 210.23 but in my opinion only a slight portion of 210.23 is applicable to a traditional dish & garb situation I am talking about.
Notice it can only comply with portions:
(A)(2) is obvious ?not fastened in place?.
(A)(1) ends ?where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.? The traditional dish & garb 20A circuit I?m talking about does not include lighting or non-fastened items, just two fastened in place loads.
I can see 422.10(A) more than (B) for the circuit in question because it leads to Art 430 II but 210.23 does not seem to address this common case.
Notice it can only comply with portions:
- 210.23 ?a branch circuit supplying two or more outlets shall supply only the loads specified according to its size as specified in 210.23(A)??
- 23(A) ?A 20A branch circuit shall be permitted to supply other utilization equipment or a combination of both?
(A)(2) is obvious ?not fastened in place?.
(A)(1) ends ?where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.? The traditional dish & garb 20A circuit I?m talking about does not include lighting or non-fastened items, just two fastened in place loads.
I can see 422.10(A) more than (B) for the circuit in question because it leads to Art 430 II but 210.23 does not seem to address this common case.
e57
Senior Member
- Location
- San Francisco, CA
Example: 12A DW - 7A GD = 19A total connected load.... On a 20A circuit.
If cord connected 210.21(B)2 would apply, and limits the total cord connected load to a maximum of 16A.
Circuits supplying two or more loads covered in 422.10(B) says to go back to 210.23... and limit cord connected (if you assume not fastened in place) to 80% of a 20a circuit - 16A - if you assume one is hard wired, and has other cord connected on it, the hard wired would be limited to 50% of 20A - 10A. (And 210.23 also says to see 210.24, which says to see 210.19~210.21... 210.20 says to see 240.3&4 etc....) So depending on how connected and how you look at it in terms of 'fastened in place' - there could be more... :roll:
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you have only have a 12 amp dishwasher and a 7 amp disposal, but don't forget that the disposal is a motor load and that 7 amp isn't really 7 amps, it will surge.
i am not sure what horse power disposal that is but they make larger ones and if that dishwasher is running in drying mode and you flip that switch on that disposal, you will trip that breaker.
e57
Senior Member
- Location
- San Francisco, CA
Actually - you probably wont trip it - most breakers will hold well over their rating for quite some time, but that's not the point.... The permissible load, and the protection of the conductors is...
In the example of with the 12 and 7 = 19
If one of those gets swapped out to gain just more than one additional amp it would definitely be a violation - no question - but the breaker would probably hold 25A for ten minutes or more before it tripped.
Either way - I think it is poor planning for the future... And if some inspector shows up at finish and adds the two up - and you find out the hard way that the plumber up-graded to this 10.2A beast, with your dishwasher at 12A - then picks up the instructions from inside it, and it says....
At that point you're screwed and failed to CYA.... JMSO
Sure in many cases you could put "Generic" DW, and "Generic" GD together on one 20A - but there are cases you cant.
ok, well...then wire it to code.
there are many things that you can do but are not wise, this would be one of them in my opinion.
who wants to be known for only doing what is necessary to just get by. when you wire high end homes, you are required to go above and beyond and think outside of the box. if you don't you will get screwd. i'd hate to see it if a ec was wiring a bunch of 1/4 million to 3/4 million dollar home in a development and homeowners kept having problems with the dw/disp circuits tripping because people put a single 15 amp or 20 amp circuit.
i'd bet sooner or later they wouldn't be wiring those homes much longer.
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tryinghard
Senior Member
- Location
- California
e57
Senior Member
- Location
- San Francisco, CA
A duplex is two recept's.... Is the other hard-wired, and using a single recept for the other?
tryinghard
Senior Member
- Location
- California
A 15A for both would most likely be a violation but 15A for each usually not.
Your policies & standards are your prerogative and a good idea to have. It has been a long time since I?ve wired a house but I am responsible for 100?s in my past most of which include one 20A circuit for the dish & garb and some 15A per each, (none of these comparables are track type); I do not recollect one call back for dish & garb circuits tripping. At any rate we can remain compliant by applying standards like yours or using one 20A circuit for both loads, the latter is safe and good if compliant maybe the real question is are these loads know before installing the circuit?
e57
Senior Member
- Location
- San Francisco, CA
The hammer meets the nail...
yeah, most loads are not known, though if you in a standard midrange track houses, sure you know what will go there.
i would feel fairly confident by running two 15amp circuits, one for each, that you would have no problems. though not too confident that there would be no problems if you were to run one 20amp circuit, it would probably work with no problems.
it just happened to be a policy where i worked that you run two 20amp circuits and the reasoning was you would never have any problems.
as many people know, often times in the resi world all it takes it one time consuming call back and your profit is toast. i guess for me, i have always done it like that so it is just normal and i don't question it and i see it as odd if it is done another way.
i would feel fairly confident by running two 15amp circuits, one for each, that you would have no problems. though not too confident that there would be no problems if you were to run one 20amp circuit, it would probably work with no problems.
it just happened to be a policy where i worked that you run two 20amp circuits and the reasoning was you would never have any problems.
as many people know, often times in the resi world all it takes it one time consuming call back and your profit is toast. i guess for me, i have always done it like that so it is just normal and i don't question it and i see it as odd if it is done another way.
tryinghard
Senior Member
- Location
- California
A 20A circuit is not a foolish risk at all with know appliance loads; it just is whats needed.
tryinghard
Senior Member
- Location
- California
e57
Senior Member
- Location
- San Francisco, CA
NO - A duplex is two recepts, the total for both would be 16A. See table 210.21(B)(2)
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