Tap rule question

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AZElectrical

Member
Location
Arizona
A co-worker asked me about this and I did not have a good answer. I am trying to determine if the following installation would be code-compliant:

Existing circuit is fed from a 480V 60A3P circuit breaker and feeds two 480V 60A receptacles. I would like to intercept the conductors to one of these receptacles at an above-slab junction box and feed a new 480V 20A receptacle within 10 feet of the junction box. The feed to the 20A receptacle would have a fused disconnect (with 20A fuses) between the tap point and the receptacle itself.

In reading through 210.19 and 240.21 I did not see anything that immediately jumped out at me as a violation, but I figured I would post here to get some other opinions.

Thanks for any input.
 

Smart $

Esteemed Member
Location
Ohio
I agree with David.

However, if you run full 60A size conductors to a 60AF/20AT disconnect, you'll not be relying on tap rules... but you'll have the ever controversial combination feeder-branch circuit.

Another alternative is to install another 60A receptacle, then make a "portable" adapter for your 20A receptacle.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
I don't see how what you describe complies with the branch circuit tap rules in 210.19.
So, the branch circuit tap rules in 210.19 seem to cover cases where no additional OCPD is required. Since the proposed installation includes OCPD at the load, isn't this a feeder tap, rather than a branch circuit tap?

Cheers, Wayne
 

david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
So, the branch circuit tap rules in 210.19 seem to cover cases where no additional OCPD is required. Since the proposed installation includes OCPD at the load, isn't this a feeder tap, rather than a branch circuit tap?

Cheers, Wayne

He has an existing branch circuit...he wants to tap it...how could it be a "feeder tap"?

240.21(B) Feeder Taps. Conductors shall be permitted to be tapped...to a feeder...

He could turn the 60A branch circuit into a feeder by adding OCPDs before the two existing receptacles, but as it exists it is a branch circuit and would have to follow the branch circuit tap rules.
 

david

Senior Member
Location
Pennsylvania
He has an existing branch circuit...he wants to tap it...how could it be a "feeder tap"?

240.21(B) Feeder Taps. Conductors shall be permitted to be tapped...to a feeder...

He could turn the 60A branch circuit into a feeder by adding OCPDs before the two existing receptacles, but as it exists it is a branch circuit and would have to follow the branch circuit tap rules.

Wouldn’t the 60 amp devices (rec.) if they fall within parameters of 250.21(B) (1) qualify them under the 10 ft. feeder tap rule.
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
To me, once he adds a downstream overcurrent device that portion of the supply circuit could just as easily be called a feeder. He meets the rules of 240.21 and I would have no problem with it.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
He has an existing branch circuit...he wants to tap it...how could it be a "feeder tap"?
By adding OCPD downstream he is turning (part of) it into a feeder. The previous configuration is immaterial to how to categorize the new configuration.

I think everyone agrees that the following is an acceptable feeder and feeder tap:

60 amp OCPD
|
60 amp conductors
|
Tap -- 20 amp conductors -- 20 amp OCPD -- 20 amp load
|
60 amp OCPD
|
60 amp load

But that second 60 amp OCPD serves no function, so delete it. The 60 amp conductors are now branch circuit conductors with respect to the 60 amp load, and feeder conductors with respect to the 20 amp load.

Cheers, Wayne
 

david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
By adding OCPD downstream he is turning (part of) it into a feeder. The previous configuration is immaterial to how to categorize the new configuration.

I think everyone agrees that the following is an acceptable feeder and feeder tap:

60 amp OCPD
|
60 amp conductors
|
Tap -- 20 amp conductors -- 20 amp OCPD -- 20 amp load
|
60 amp OCPD
|
60 amp load

But that second 60 amp OCPD serves no function, so delete it. The 60 amp conductors are now branch circuit conductors with respect to the 60 amp load, and feeder conductors with respect to the 20 amp load.

Cheers, Wayne

I don't agree that that arrangement is acceptable. Where does the Code permit conductors to be both feeders and branch circuits? If you have a branch circuit that you want to tap, 240.21(A) directs you to 210.19 and 210.20.
 

david

Senior Member
Location
Pennsylvania
Where would the final branch-circuit overcurrent device be for those Rececptacles?

Yes it is currently intended to be a branch circuit by definition .

The question is can you tap a 60 amp feeder with two 60 amp rec. without individual over current protection ahead of the two 60 amp rec.
 

david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
Yes it is currently intended to be a branch circuit by definition .

The question is can you tap a 60 amp feeder with two 60 amp rec. without individual over current protection ahead of the two 60 amp rec.

If there is no overcurrent protection ahead of the two 60 amp receptacles, then the circuit is still a branch circuit. You cannot apply feeder tap rules to a branch circuit.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
I don't agree that that arrangement is acceptable.
By "that arrangement" I assume you mean with the second 60 amp OCPD deleted. What code section forbids?

Where does the Code permit conductors to be both feeders and branch circuits?
The code is permissive, where does it prohibit a conductor from serving as both a feeder and as a branch circuit? The definitions clearly overlap, as in the case of my ASCII art arrangement with the second 60 amp OCPD deleted.

Cheers, Wayne
 

david

Senior Member
Location
Pennsylvania
Can I build a feeder from scratch that has two 60 amp rec. without overcurent protection ahead of them and a 20 amp rec. with 20 amp overcurrent ahead of the rec. and if so what size would the feeder have to be?

Are you saying I have to disassemble the 60 amp branch circuit and build a feeder from scratch that looks exactly like what I would have had if I just would add the 20 amp portion to it.

The initial question I had in looking at this was what is the load for the rec. evolved?

I do not have anything to add so I'll step back and watch this discussion develop from others input
 

david luchini

Moderator
Staff member
Location
Connecticut
Occupation
Engineer
By "that arrangement" I assume you mean with the second 60 amp OCPD deleted. What code section forbids?


The code is permissive, where does it prohibit a conductor from serving as both a feeder and as a branch circuit? The definitions clearly overlap, as in the case of my ASCII art arrangement with the second 60 amp OCPD deleted.

Cheers, Wayne

The Code defines a feeder as all conductors from the source to the final branch-circuit overcurrent device, and a branch circuit as the circuit conductors between the final overcurrent device protecting the circuit and the outlets(s). I don't see any overlap in those definitions, I see a clear demarcation.

240.21(A) applies to branch circuit taps and 240.21(B) applies to feeder taps. The existing circuit that is intended to be tapped is a branch circuit, not a feeder. The 240.21(B) rules do not apply to tapping a branch circuit and therefore cannot be used to tap the existing circuit.
 

wwhitney

Senior Member
Location
Berkeley, CA
Occupation
Retired
240.21(A) applies to branch circuit taps and 240.21(B) applies to feeder taps. The existing circuit that is intended to be tapped is a branch circuit, not a feeder. .
Sure, but tapping it and adding OCPD turns it into a feeder. The previous configuration doesn't matter.

The Code defines a feeder as all conductors from the source to the final branch-circuit overcurrent device, and a branch circuit as the circuit conductors between the final overcurrent device protecting the circuit and the outlets(s). I don't see any overlap in those definitions, I see a clear demarcation.

Conductors may run between one OCPD and an outlet while simultaneously supplying another OCPD. That makes them both a branch circuit with respect to the the outlet, and a feeder with respect to the second OCPD, under the definitions. I'm unaware of anything that prohibits this.

Consider this general arrangement:

OCPD A
|
Conductors A
|
TEE -- Conductors B -- OCPD B -- Load B
|
Conductors C
|
[Possible OCPD C]
|
Load C

1) If OCPD C is present, then Conductors A, B, and C are feeder conductors. If the ampacity of Conductors B or C is less than the rating of OCPD A, then the feeder tap rules need to be met.

2) If OCPD C is absent, and all Conductors A, B, and C are of ampacity not less than the rating of OCPD A, then there are no taps. Conductors A are a branch circuit with respect to Load C, and a feeder with respect to Load B. Conductors B are a feeder only, and Conductors C are a branch circuit only.

3) If OCPD C is absent, and Conductors B are of ampacity less than the rating of OCPD A, then the feeder tap rules apply.

4) If OCPD C is absent, and Conductors C are of ampacity less than the rating of OCPD A, then the branch circuit tap rules apply.

I think we agree on (1). Do we agree on (2), or are you saying this is a prohibited configuration? If so, what prohibits it? (3) is the OP's situation we are discussing. I think also we agree on (4)?

Cheers,
Wayne
 

jap

Senior Member
Occupation
Electrician
Why not just install a J-box, make a splice, install 60 amp rated wire to a 60 amp fused disconnect, install 20 amp fuses in the disconnect with 60 to 30 amp fuse reducers, feed a 20 amp receptacle below the disconnect and be done with it?

JAP>
 

augie47

Moderator
Staff member
Location
Tennessee
Occupation
State Electrical Inspector (Retired)
The receptacles are devices, the 20 amp disconnect is a device. The circuit, to me, is a feeder supplying three devices.
 
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