- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
How would that be compliant for 240.24(A)
I never heard this before
- Thread starter Ponchik
- Start date
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That is a good point. But 240.24(A)(4) will get him off the hook.
240.24(A) height regulation is about the handle of the switch and breaker. The only thing about the over current protection device in that section, is it has to be accessible. The fuse is accessible.
I also think 240.10 will allow him to do his install.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
This has been debated here before with no general consensus on total acceptance or disallowance of such a setup. Maybe even was over a range circuit supplying a microwave, and I do recall Dennis's washer supplied from a 30 amp dryer circuit coming up before as well.
If you tap the range circuit and install that fused device - you can create a legimate feeder tap and new branch circuit. Now what do you call the remaining portion supplying the range that doesn't specifically meet either feeder or branch circuit definition? (this was one area that had no consensus in the past and opinions were all over the board on that one)
If you do create a new branch circuit with that fused device - where do you place it? If it is a supplemental overcurrent device it can go anywhere as long as it is accessible, if it is a branch circuit overcurrent device it needs to be readily accessible, and most would say it also needs 110.26 working clearances around it as well so it isn't going behind the range or in the cabinet with or adjacent to the microwave.
One other thing not mentioned but probably a common issue by the appliance installer that says they do this is they likely just make the tap by inserting the 12 AWG into the same terminal of the range receptacle that the supply conductors land in - which very likely are only designed for a single conductor to be installed in.
If you have an old range circuit that is still allowed by exception to use the neutral conductor to ground the frame of the appliance - you are still fine with the range - but you create more violations when you feed additional loads that don't qualify as cooking equipment that is permitted to use that exception for equipment grounding.
I don't know of any appliance that has a 5-15 cord connector that is permitted to have the neutral also provide equipment grounding functions, that is pretty much limited to cooking appliances that have the option of supplying with a cord and plug or with "hard wired" methods - typical examples are ranges, ovens, cooktops that operate at over 2000 watts and over 120 volts, but may contain 120 volt loads within the appliance. There may be some standards on electrical characteristics required for this application - this is just my general observation and I kind of am mixing the 5-15 supply cord with the branch circuit tap allowance for cooking appliances here as well.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I believe those three letters though they kind of do create an acronym are actual catalog numbers so to speak of Bussman's versions of those devices. Though I don't know if anyone else even makes such devices. I think I may have seen re-labeled Bussman devices though.
macmikeman
Senior Member
- Location
- Planet macmikeman
It wont be legal to use that in a dwelling unless they make one in a tamper resistant version.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I almost went off on using a type S fuse adapter in it, but then I realized you were getting at the tamper resistant receptacle. But also you can use non TR receptacles in dwelling if it is more then 5.5 feet above the floor - which is typical for those microwave applications like in the OP anyway.
This installation is OK!
210.19.A.3 exp 1
Conductors tapped from a 50A branch circuit supplying electrical ranges, wall-mount electrical ovens, and counter-mount electrical cooking units shall have an ampacity of not less than 20A
1. shall have an ampacity of not less than 20A
2. shall be sufficient for the load to be served.
I believe it means, conductors tapped from a 50A or 40A electrical oven branch circuit or cooking unit to supply other appliances
the tap conductors shall have an ampacity not less than 20A and shall be sufficient for the load it served, and the taps shall not be longer than necessary for servicing the appliance.
Also each tap conductors shall not supply more than one appliance, and min 12 awg.
210.19.A.3 exp 1
Conductors tapped from a 50A branch circuit supplying electrical ranges, wall-mount electrical ovens, and counter-mount electrical cooking units shall have an ampacity of not less than 20A
1. shall have an ampacity of not less than 20A
2. shall be sufficient for the load to be served.
I believe it means, conductors tapped from a 50A or 40A electrical oven branch circuit or cooking unit to supply other appliances
the tap conductors shall have an ampacity not less than 20A and shall be sufficient for the load it served, and the taps shall not be longer than necessary for servicing the appliance.
Also each tap conductors shall not supply more than one appliance, and min 12 awg.
JDB3
Senior Member
- Location
- San Antonio, Texas
But, what about the AFCI requirement for the kitchen :?
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I don't believe they intend for you to supply a 5-15/5-20 receptacle outlet from the tap allowed by that section.
I do agree there is confusion here as a microwave oven is to most people a cooking appliance - yet in general NEC only seems to recognize ranges, ovens, cooktops as cooking appliances for most sections that deal with cooking appliances.
I do believe they intend such taps to be used for cooking appliances that typically do not have a factory installed cord / cord cap, or if the tap were to supply a receptacle outlet it would need to be a 50 amp receptacle if overcurrent protection is 40-50 amps.
It is confusing, 210.19 is not talking about sub-panel feeder tap, it's talking appliance tap into electrical range circuit.
usually no one will do it this way, but what if before final inspection the home owner decide to add a microwave oven above counter cabinet. How to add a new dedicate circuit for this microwave oven?
In residential, usually only HVAC & electrical range will have 40A or 50A branch circuit, and usually a 40A od 50A branch circuit will supply to the back of electrical range, and either terminate in a 4x4 j-box or an dedicate 220V outlet.
At the end all cabinets installed, tiles done the exception 1. gives you an alternative way to supply electricity to this microwave oven with 3 conditions 1. Shall have 1/2 of ampacity of the circuit being tapped.
2. The tap wires not be less than 20A, and sufficient for the
load to be served. "no other add in outlets"
3. The taps shall not be longer than necessary for the appliance it serve.
usually no one will do it this way, but what if before final inspection the home owner decide to add a microwave oven above counter cabinet. How to add a new dedicate circuit for this microwave oven?
In residential, usually only HVAC & electrical range will have 40A or 50A branch circuit, and usually a 40A od 50A branch circuit will supply to the back of electrical range, and either terminate in a 4x4 j-box or an dedicate 220V outlet.
At the end all cabinets installed, tiles done the exception 1. gives you an alternative way to supply electricity to this microwave oven with 3 conditions 1. Shall have 1/2 of ampacity of the circuit being tapped.
2. The tap wires not be less than 20A, and sufficient for the
load to be served. "no other add in outlets"
3. The taps shall not be longer than necessary for the appliance it serve.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
You still can not supply that single 15 amp receptacle outlet from a 40 or 50 amp circuit, no matter what normally plugs into it. The appliance tap you mention is commonly used for cooktops or wall ovens. You can run a 40 or 50 amp circuit and tap both a oven and a cooktop from it, that have only 20 amp conductors in the "whip", per (A)(3) household ranges and cooking appliances, I see some of what you mention in there, but do not see the "1/2 ampacity of circuit being tapped" at all.
You possibly can tap the range circuit and supply a 15 amp 120 volt receptacle, but you will need a 15 amp overcurrent device for a single receptacle or can have a 20 amp device if more then one receptacle, but you have essentially created a new branch circuit - and very likely will have to apply 110.26 working clearances to that overcurrent device - plus it needs to be rated as a branch circuit device. Then comes the argument that has never been solved - is the original range circuit now a feeder - if so how by definition can it have the range outlet connected to it, outlets are on branch circuits.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I do have electronic copy of 2011 handbook, I see about same commentary you mentioned in there - I still don't see it applying to a 15 amp 120 volt receptacle, though it also is not specifically prohibited. Good luck convincing most any inspector that this is permitted in any edition of NEC since at least 1970's and possibly even further back then that.
This exception was for connecting cooking appliances - though the microwave in question may or may not be considered a cooking appliance. In general when NEC is talking about cooking appliances microwaves don't seem to be included in the discussion. Definitions involving permanent provisions for cooking always seem to not recognize a microwave as permanent provisions for cooking - they don't directly exclude them, but most discussions on this usually don't recognize a microwave as permanent provisions for cooking. This very topic does get attention at times here on the forum, I wish NEC would clarify whether a microwave is considered permanent cooking appliance or not for it's own application, as it makes a difference in some areas.
Also handbook commentary is nothing more then the opinion of the person(s) that wrote the commentary. It is not official NFPA interpretations of the code content itself. The handbook just happens to be published by NFPA, but only the non tinted panels in printed sections are the actual code, the content in tinted panels is commentary from outside the code itself.
from the end of the preface in 2011 handbook:
I'm sure other editions of the handbook have same thing or very similar printed somewhere in the preface of the book.
Why did people need NEC to clearly specify certain appliances is a cooking appliance in order to be use as a cooking appliance?
OK! 210.19.A.3 For range of 8.75 kw or more rating, the minimum branch circuit rating shall be 40A.
If I have a electric potable stove tap into 40A range circuit should comply with NEC, then why microwave can not?
I'm an electrician, and both comm & res electrical ICC certs.
NEC is for safety, if it's unsafe I'll write correction.
OK! 210.19.A.3 For range of 8.75 kw or more rating, the minimum branch circuit rating shall be 40A.
If I have a electric potable stove tap into 40A range circuit should comply with NEC, then why microwave can not?
I'm an electrician, and both comm & res electrical ICC certs.
NEC is for safety, if it's unsafe I'll write correction.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
I tried to mention before NEC is not clear on whether or not it considers a microwave as a cooking appliance. If majority of them out there did not have a 5-15 cord cap on them I think they would be treated differently. Problem we have with 5-15 receptacles is you just can not dedicate them to anything - people will plug power strips, multi-tap's, etc. into them to run other items, then you do have a problem as the exception under discussion here is not intended to supply other then cooking appliances. This is before we even get into possible needed overcurrent protection, GFCI protection or AFCI protection, or if an older 120/240 3 wire circuit we have issues with using the grounded conductor for equipment grounding purposes as well.
Next thing that possibly happens is we have this 5-15 receptacle supplied from a 40 or 50 amp circuit and someday someone decides to extend more 120 volt outlets from that receptacle location - now we have multiple 15/20 amp receptacles all tapped into a 40 or 50 amp circuit.
I think maybe the NEC should at least change wording to indicate this tap can only feed 240 volt or 120/240 volt appliances or at least not to supply 15/20 amp 120 volt receptacle outlets. I have a feeling that is the intention here but it is not written all that clearly.
After all that has been said I think maybe I should have been looking for a different code section - how about 210.21(B)?
That would not permit you to directly tap a 15 20 or 30 amp receptacle to a 40 or 50 amp circuit. If you tap and put proper overcurrent protection before the receptacle - it may fly - but now we get into the dilemma that has been brought up before about differences between feeders and branch circuits, and whether or not the overcurrent device has to be a branch circuit protective device or if it can be a supplemental type device. If it is a branch circuit device it must be readily accessible, if it is supplemental is doesn't have to be readily accessible - this is in 240.10.
There is also this in 210.23:
Some microwaves are fastened in place, some are not, most marketed for residential use have a 5-15 cord cap on them anyway. The turbochef ovens or similar mostly found in non dwellings usually have more then a 15-20 amp 120 volt circuit needed and I believe many of those could be tapped onto the circuit in question here.
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