Tapping in to range for microwave receptacle outlet.

[david luchini]

If so, seems like you could tap the range the circuit to provide a 20A OCPD to protect a receptacle for a microwave (IIRC the sections cited in the OP).

That wouldn't be Code compliant.

 

[wwhitney]

That wouldn't be Code compliant.

What section would that violate?

Thanks,
Wayne

 

[david luchini]

What section would that violate?

210.19. A branch circuit tap has to meet the requirements for branch circuit taps as spelled out in 210.19. What you have described doesn't.

 

[rambojoe]

I get it now, current is constant in a circuit. So if 40 amps are going through the breaker on one leg, then 40 amps are also going through the other leg. I just had to think about it logically for a second. Did you remember to put cover sheet on the TPS report?

Constant is not quite a good word.. Think alternating, and its not constant. Also, the most helpful advice is to learn watts and volt load formulas forwards and backwards to really see what happens to current when voltages increase (or decrease, be it in phase degrees or resistance) by any amount. Resistance is second... But not as fun to a wireman (oh, but important). Bam, it alternates and basic load calc! You now know as much as Mr. Holt!

 

[wwhitney]

210.19. A branch circuit tap has to meet the requirements for branch circuit taps as spelled out in 210.19. What you have described doesn't.

Well, with respect to 210.19, paragraph (A)(3) Exception 1 includes the language "The taps shall not be longer than necessary for servicing the appliance." So that would preclude running the tap conductors any significant distance to a readily accessible location for the OCPD. But if you were able to intercept the existing range wiring at a readily accessible location, then that language would be satisfied. I don't see any other impediments in 210.19(A)(3) Exception 1.

However, 210.19 does not apply to these tap conductors, as they are not branch circuit conductors, since they have downstream OCPD between them and the load. So they would be governed by 240.21(B).

Cheers, Wayne

 

[Sea Nile]

Constant is not quite a good word.. Think alternating, and its not constant.

Depends on the context. At any point in time current in a series circuit should be constant across all loads, OCPDs, conductors.

If the voltage or current from the source changes, it will change simultaneously through the series circuit making every part of the series circuit have the same current at any specific instance in time.

When I remembered that law if series circuits, everything clicked and it made sense.

 

[david luchini]

However, 210.19 does not apply to these tap conductors, as they are not branch circuit conductors, since they have downstream OCPD between them and the load. So they would be governed by 240.21(B).

How would you have a "feeder tap" from a 40A "branch circuit."

The circuit being tapped is a branch circuit, not a feeder, and is therefore not governed by 240.21(B).

 

[rambojoe]

If there is a context for you, then all the more "power" to ya.
And yes, when the voltage changes, the voltage changes.
But it is not constant. Only when its "on". And then, its still not constant. Meh, thats why i tried to get you off that word and on our word, a/c.

 

[rambojoe]

This trade is full of oddball ways to remember things.. but some are harmful to continue to elevate our learning and understanding... i wasnt trying to be mean, by far. Or political for once!

 

[Sea Nile]

This trade is full of oddball ways to remember things.. but some are harmful to continue to elevate our learning and understanding... i wasnt trying to be mean, by far. Or political for once!

Dude, I like you.

 

[rambojoe]

Also, dont worry about series a/c stuff. I tried wiring things that way my first hour on the job and got yelled at... you will probably never wire series anytime soon... in houses. I like all electricians except the jw's and foreman who will never take a minute to explain things, at least correctly, ever. Usually a reason why thats not me

 

[wwhitney]

How would you have a "feeder tap" from a 40A "branch circuit."

Because per the NEC definitions a conductor can obviously be both a branch circuit and a feeder. As the configuration I described demonstrates.

The circuit being tapped is a branch circuit, not a feeder, and is therefore not governed by 240.21(B).

Adding the 20A OCPD makes it a feeder with respect to the receptacle. And 240.21(B) precisely covers the case at hand, where the conductors do have overload protection, but not at their point of supply. Unlike branch circuit taps, where the conductors do not have overload protection.

Cheers, Wayne

 

[rambojoe]

Dude, I like you.

Everyone here had the moment of walking onto a job and suddenly realizing they dont know squat. Everybody.
Mine was my first food production line job... mind boggling. Luckily i was just piping ridgid sensor drops all day. That night i got a book on symbols and assembly line/commercial motor control..

 

[david luchini]

Because per the NEC definitions a conductor can obviously be both a branch circuit and a feeder. As the configuration I described demonstrates.

That's certainly not "obvious". In fact, it's obviously incorrect.

Adding the 20A OCPD makes it a feeder with respect to the receptacle. And 240.21(B) precisely covers the case at hand, where the conductors do have overload protection, but not at their point of supply. Unlike branch circuit taps, where the conductors do not have overload protection.

Cheers, Wayne

The circuit has to be a feeder in order to make a tap to it in accordance with 240.21(B). "Conductors shall be permitted to be tapped...to a feeder..."

I don't see anything in 240.21(B) about making a tap to a branch circuit to magically turn the branch circuit into a feeder.

And there is nothing in the branch circuit tap section about terminating branch circuit tap conductors on either an OCPD or a receptacle.

 

[rambojoe]

Oops... ok, switches are fundamentaly series.. i had to correct myself but, regular switches are'nt a load.. im actually racking my brain wondering what else we do in series in a normal house.. excluding doorbells and g.door sensors... am i forgetting something?

 

[Sea Nile]

Everyone here had the moment of walking onto a job and suddenly realizing they dont know squat

For me, I started binge watching M.Holt videos while I was still in the army 2 years before I got out. Along with many other sources that I won't mention here. But I also made a huge investment purchasing his training library and studying that. Day 1 of when I started in the trade, I knew a lot of things that others i worked with didn't know. Plus I had a code book which very few people had.
What i was lacking was the hands on part. But I've proven myself to my co workers and have actually inspired some of them to dig more into studying and working towards getting their license.
I tell them that I love being wrong, it gives me the chance to change my thinking and makes me better.
Even on this forum I love it when I'm wrong. But it doesn't happen very often, I'm usually right. . I'm working towards the day that I can say what my favorite person says, "ultimately, I'm always right". But I'm not there yet.

 

[Sea Nile]

[QUOTE="rambojoe, post: 2779864, member: 146762". im actually racking my brain wondering what else we do in series
[/QUOTE]

As it pertains to the breakers, which is what I was referring to, it's series, leg to leg through two breakers. It doesn't matter if you had 20 in line fuses or in line ocpd's. The current running through all of them will be the same. It doesn't matter if they Break off into parallel circuits down the line, that part is transparent at the panel.

 

[wwhitney]

That's certainly not "obvious". In fact, it's obviously incorrect.

I agree, obvious was a poor choice of words. But there's nothing in the definitions of branch circuit and feeder that makes them mutually exclusive.

Let's take a simpler example: suppose there's a 50A circuit supplied by a 50A OCPD. I run that circuit to a >=50A MLO panelboard with feed thru lugs. In the panelboard I put a single 20A OCPD. The feed thru lugs go to a 14-50 receptacle. The 20A OCPD supplies a 20A circuit to 5-15 duplex receptacle.

Now, does anything in the NEC prohibit that arrangement? If not, what are the 50A conductors from the 50A OCPD to the MLO panelboard? Answer: they are a branch circuit with respect to the 14-50 receptacle, and they are a feeder with respect to the 5-15 receptacle.

The circuit has to be a feeder in order to make a tap to it in accordance with 240.21(B). "Conductors shall be permitted to be tapped...to a feeder..."

And adding that 20A OCPD makes it a feeder. I agree that if there were no downstream OCPD, then it couldn't be a feeder tap, and would be a branch circuit tap.

Cheers, Wayne

 

[david luchini]

I agree, obvious was a poor choice of words. But there's nothing in the definitions of branch circuit and feeder that makes them mutually exclusive.

Of course there is. When I have my 40A branch circuit that I propose to tap....The 40A c/b is the final overcurrent device protecting the circuit.

When I add another ocpd down stream, is the 40A c/b now the "semi-final" device protecting the circuit? Or maybe the "sorta-final" device protecting the circuit. Or perhaps "finalish".

A feeder is the circuit conductors between the source and the final branch-circuit overcurrent device. A branch circuit is the circuit conductors between the final branch-circuit over current device and the outlet(s). There is no overlap.

And if I have a branch circuit, I cannot make a "feeder tap" to it per 240.21(B), because it is not a feeder.

 

[wwhitney]

When I have my 40A branch circuit that I propose to tap....The 40A c/b is the final overcurrent device protecting the circuit.

Until you add another OCPD in the manner I suggested, and then it is no longer the final overcurrent device with respect to at least one of the outlets. While remaining final with respect to another of the outlets. "Final" is relative to a given endpoint.

A feeder is the circuit conductors between the source and the final branch-circuit overcurrent device. A branch circuit is the circuit conductors between the final branch-circuit over current device and the outlet(s). There is no overlap.

There may be no overlap if there is an NEC section that prohibits the arrangement I described in my last post. If there is no such prohibition, then that arrangement demonstrates that the definitions may (rarely) overlap. The definitions are outlet-specific, and the status of a conductor may vary depending on the outlet referenced.

So what NEC section prohibits the circuit arrangement I described?

Cheers, Wayne