210.19(A)(3) Exception 1

[tortuga]

Old modern style house, concrete slab, vaulted ceiling, that has a 210.19(A)(3) Exception 1 setup.
No remodeling going on customer is just replacing the built in microwave oven.
They appear to have a 50A circuit that feeds a 50A range receptacle and a 20A 240V receptacle in a upper cabinet for the old microwave oven.
I am not sure the route of the branch circuit conductors to the microwave, and have no idea if they are 50 amp the whole way, if say they are, can this outlet be converted to a 20A 120V single receptacle for a new 120V microwave?
Normally I just run a new microwave circuit, but this would be a royal job to do.

 

[augie47]

IMO, that exceptions does not include microwaves.

 

[brantmacga]

IMO, that exceptions does not include microwaves.

“Exception No. 1: Conductors tapped from a branch circuit supplying electric ranges, wall-mounted ovens, and counter-mounted electric cooking units shall have an ampacity of not less than 20 amperes and shall be sufficient for the load to be served. These tap conductors include any conductors that are a part of the leads supplied with the appliance that are smaller than the branch- circuit conductors. The taps shall not be longer than necessary for serv- icing the appliance.”


I’m not so sure. A microwave is technically an oven, and in this case, a wall-mounted oven. If it were on the counter, could we then call it a counter-mounted electric cooking unit? That’s a very broad definition, certainly on purpose.

This is an interesting question. If we’re following Charlie’s rule here, it says what it says, and it doesn’t say what it doesn’t say. I see no voltage restrictions here. I also don’t see anything that says it has to be hardwired.

The more important question I think is how many conductors are in the circuit? I would think this is a 3-wire 240v circuit being that it’s an older house.


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[tortuga]

Thanks all I guess it all depends on if a microwave is a "wall-mounted electric oven", its odd the CMP took the time to define 'cooking unit, counter-mounted' but not "wall-mounted electric oven". Some microwaves also have a heating element, but who knows what they will get as I am just being asked to replace the receptacle.

I did get a late update that the J box has 50Amp newer wire in it:

 

[letgomywago]

Is this microwave called a "speed oven"

 

[LarryFine]

Ideally, a sub-panel would allow protecting everything.

 

[brantmacga]

Thanks all I guess it all depends on if a microwave is a "wall-mounted electric oven", its odd the CMP took the time to define 'cooking unit, counter-mounted' but not "wall-mounted electric oven". Some microwaves also have a heating element, but who knows what they will get as I am just being asked to replace the receptacle.

A microwave is by definition an oven.

I did get a late update that the J box has 50Amp newer wire in it:

Then you are good to go. Full send.

 

[tortuga]

As an update to this odd ball situation, another option that surfaced is one of these Bussman covers that have a receptacle and a fuse.
They actually make a version that is a 4S cover.

A co-worker calls this a british style plug because 'all plugs in the UK are fused' not sure if that is accurate.
Using this supplemental protection can be provided. Granted that is only a 15A receptacle, and that is not a type-S fuse holder.
I'd probably put a 20A fuse in it for a I am guessing a ~1500W microwave.

 

[letgomywago]

As an update to this odd ball situation, another option that surfaced is one of these Bussman covers that have a receptacle and a fuse.
They actually make a version that is a 4S cover.
View attachment 2564244
A co-worker calls this a british style plug because 'all plugs in the UK are fused' not sure if that is accurate.
Using this supplemental protection can be provided. Granted that is only a 15A receptacle, and that is not a type-S fuse holder.
I'd probably put a 20A fuse in it for a I am guessing a ~1500W microwave.

View attachment 2564243

I think this wouldn't be compliant because of not being readily accessible behind a built in unit but I don't think it would ever have issues since fuses don't really "nuisance trip"

 

[tortuga]

Yeah, would not be easy to get to at all, I think going by the letter of the code Brant is probably correct in post #7, the branch circuit OCPD could be the 40A breaker and a regular single recept could go in there.
This would be a 'supplemental' protection fuse for peace of mind.

 

[kwired]

Does the original cable feeding this have separate grounded and EGC?

If only 3 wire was likely compliant at time of install, but any extension made off of it may not been compliant at the time extension was made.

I could be wrong but I don't think that you can tap a 20 amp receptacle off that 50 amp circuit, at least not without supplemental overcurrent protection. You can have multiple 50 amp receptacles or could direct connect other cooking appliances to said circuit though, if they are designed for direct connection which typically means they will be fixed in place type appliances or a conventional "range". I find it a little hard to believe you might find a 120 volt appliance that could be used in this setup, 208-240/120 yes you probably could use it but if cord and plug connected would need to be 50 amp receptacle.

 

[brantmacga]

Does the original cable feeding this have separate grounded and EGC?

yes, that was discussed above.

I could be wrong but I don't think that you can tap a 20 amp receptacle off that 50 amp circuit, at least not without supplemental overcurrent protection.

This is the text from the NEC

(3) Household Ranges and Cooking Appliances. Branchcircuit
conductors supplying household ranges, wall-mounted
ovens, counter-mounted cooking units, and other household
cooking appliances shall have an ampacity not less than the
rating of the branch circuit and not less than the maximum
load to be served. For ranges of 8¾ kW or more rating, the
minimum branch-circuit rating shall be 40 amperes.
Exception No. 1: Conductors tapped from a branch circuit supplying electric ranges, wall-mounted ovens, and counter-mounted electric cooking units shall have an ampacity of not less than 20 amperes and shall be sufficient for the load to be served. These tap conductors include any conductors that are a part of the leads supplied with the appliance that are smaller than the branch- circuit conductors. The taps shall not be longer than necessary for serv- icing the appliance.

There is no requirement for supplemental overcurrent protection on the tap conductors mentioned anywhere in 210.19.

 

[augie47]

Maybe just me.....
It's not detailed in 210.19 but it just seems a bit sketchy to have a 120v receptacle with #12 (?) fed from that tap (as opposed to a hard wired cooking appliance) especially a duplex... lends itself to something other being plugged in a a future date.
Al.so, to me, a bit concerning to have a microwave protected by a 40 or 50 amp OCP device.

 

[letgomywago]

Maybe just me.....
It's not detailed in 210.19 but it just seems a bit sketchy to have a 120v receptacle with #12 (?) fed from that tap (as opposed to a hard wired cooking appliance) especially a duplex... lends itself to something other being plugged in a a future date.
Al.so, to me, a bit concerning to have a microwave protected by a 40 or 50 amp OCP device.

I'd do a simplex outlet with a note on the cover. I have seen a speed oven bolted to a standard wall oven and they had 1 single pigtail. The microwave speed oven was tapped inside the UL listed oven and was from the factory that way. I have also seen them bolted together with 2 separate pigtails and instructions to have separate circuits.

 

[tortuga]

Maybe just me.....
It's not detailed in 210.19 but it just seems a bit sketchy to have a 120v receptacle with #12 (?) fed from that tap (as opposed to a hard wired cooking appliance) especially a duplex... lends itself to something other being plugged in a a future date.

No I entirely agree its sketchy, I posted a pic of what was there, its a 4S deep box with #8's in it, and the tap is 6 inches of #12 to a 240 Volt single. It had passed an inspection during a remodel about 20 years ago..

Al.so, to me, a bit concerning to have a microwave protected by a 40 or 50 amp OCP device.

Augie what do you think of the fused receptacle I posted in post #8

 

[Dennis Alwon]

Why would you mess with the 50 amp circuit if you have a 20 amp 240V circuit there? Just change that to a 120V and be done. What am I missing

 

[brantmacga]

Why would you mess with the 50 amp circuit if you have a 20 amp 240V circuit there? Just change that to a 120V and be done. What am I missing

OP said "Old modern style house, concrete slab, vaulted ceiling, that has a 210.19(A)(3) Exception 1 setup."

Its not a dedicated 240v circuit, its tapped off the 50A 120/240v circuit. He needs to change the taps from a 240v circuit to a 120v circuit, and needed to verify this is also compliant with the Exception listed in 210.19(A)(3).

 

[curt swartz]

How would connecting a 15 or 20 amp receptacle to a 50 amp overcurrent device comply with 210.21(B)1?

The 14/3 or possibly even 16/3 cord on the microwave is not rated for 20 amps as required by 210.19(A)3 EX 1.

Appliances that come with 15 plugs are only tested listed for connection to 15 or 20 amp branch circuit.

Many years ago a kitchen remodeling contractor asked me to meet at a job to disconnect an old oven and reconnect a new oven. He new he was going to need to do some minor cabinet modifications. When we get there the old over was a double over with a microwave on top. The new oven was actually 2 separate ovens, 1 single standard oven and 1 microwave. We started looking to see how we could get a new circuit for the microwave but realized we would have to do major wall and ceiling demo. I ended up using the buss fuse holder receptacle behind the microwave.

 

[brantmacga]

How would connecting a 15 or 20 amp receptacle to a 50 amp overcurrent device comply with 210.21(B)1?

The 14/3 or possibly even 16/3 cord on the microwave is not rated for 20 amps as required by 210.19(A)3 EX 1.

Appliances that come with 15 plugs are only tested listed for connection to 15 or 20 amp branch circuit.

Many years ago a kitchen remodeling contractor asked me to meet at a job to disconnect an old oven and reconnect a new oven. He new he was going to need to do some minor cabinet modifications. When we get there the old over was a double over with a microwave on top. The new oven was actually 2 separate ovens, 1 single standard oven and 1 microwave. We started looking to see how we could get a new circuit for the microwave but realized we would have to do major wall and ceiling demo. I ended up using the buss fuse holder receptacle behind the microwave.

That’s a good point, but i don’t see anything in the exception of 210.19(A)(3) that says you must comply with 210.21. As for the cord, I would say that it’s part of the listed assembly of the microwave. I think the wire leads are mentioned because some built-in microwaves can be hardwired.

 

[wwhitney]

That’s a good point, but i don’t see anything in the exception of 210.19(A)(3) that says you must comply with 210.21.

Yes, but nothing exempts you from it. If you are going to use a receptacle in your tap, rather than hard wire the equipment, then you'll need to comply with the receptacle rules as well as 210.19(A)(3) exception.

Cheers, Wayne