Tap Rule Confusion

[david luchini]

Sure, not there, but in the first sentance of 240.21. "Overcurrent protection shall be provided in each ungrounded circuit conductor . . ."

They then go on to specify or allow the locations.

You are missing where they say "EXCEPT as specified in 240.21(A) through (H)." The EXCEPTION in 240.21(C)(2)(1)(b) does not require the conductors to terminate on an OCPD where they land on a "device."

 

[Smart $]

You are missing where they say "EXCEPT as specified in 240.21(A) through (H)." The EXCEPTION in 240.21(C)(2)(1)(b) does not require the conductors to terminate on an OCPD where they land on a "device."

No...

You are taking the exception clause out of context. Specifically, it says...

240.21 Location in Circuit. Overcurrent protection shall
be provided in each ungrounded circuit conductor and shall
be located at the point where the conductors receive their
supply except as specified in 240.21(A) through (H). Conductors
supplied under the provisions of 240.21(A) through
(H) shall not supply another conductor except through an
overcurrent protective device meeting the requirements of
240.4

Note there is no comma between 'supply' and 'except'. Therefore the except clause only applies to where overcurrent protection is located.

And how does that apply to 240.21(C)(1)? The secondaries from a transformer that are protected by the primary OCPD do NOT have a fuse or overcurrent trip unit of a circuit breaker connected in series with each ungrounded conductor.

240.21(C)(1) does modify the overcurrent protection actually being in the circuit conductor but under limited conditions, where primary current is, with few exceptions, always proportional to secondary current. 240.21(C)(1) is an excepted case to the 240.21 general statement and the wording could better indicate such.

 

[david luchini]

No...

You are taking the exception clause out of context. Specifically, it says...
Quote:
240.21 Location in Circuit. Overcurrent protection shall
be provided in each ungrounded circuit conductor and shall
be located at the point where the conductors receive their
supply except as specified in 240.21(A) through (H). Conductors
supplied under the provisions of 240.21(A) through
(H) shall not supply another conductor except through an
overcurrent protective device meeting the requirements of
240.4

Note there is no comma between 'supply' and 'except'. Therefore the except clause only applies to where overcurrent protection is located.

I disagree. If it had said "Overcurrent protection shall be provided in each ungrounded circuit conductor. The overcurrent protection shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (H)" then I would agree. If it had said "Overcurrent protection shall be provided in each ungrounded circuit conductor, and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (H)" then I would agree. But what is says is you have to do "A" and "B" except as permitted in "C." The exception applies to both "A" and "B".

240.21(C)(1) does modify the overcurrent protection actually being in the circuit conductor but under limited conditions, where primary current is, with few exceptions, always proportional to secondary current. 240.21(C)(1) is an excepted case to the 240.21 general statement and the wording could better indicate such.

So 240.21(C)(1) is not required to comply with 240.15, but 240.21(C)(2) is? That's selective application of the code. Nothing in 240.21(C)(1) says the requirements of 240.15 don't apply. If (C)(2) must comply with 240.15, then (C)(1) must also comply with 240.15.

Nor does anything in the text say 240.21(C)(1) is an "excepted" case to the 240.21 general statement. In fact, the text of 240.21(C) seems to give equal weight to (C)(1) through (C)(6.) You are reading something into the code which is simply not there.

 

[RB1]

240.21(C)(1) is intended to clarify that the secondary conductors in certain conditions are considered to be protected by the primary OCPD. In those cases the secondary conductors are already protected where they receive their supply. The tap rules really don't apply in those cases.

If 240.21(C)(2) intended for ten foot secondary conductors to terminate into an overcurrent device, why include the language "Not less than the rating of the of the device supplied by the secondary conductor or not less than the rating of the overcurrent protective device at the termination of the secondary conductors." You are given the option. I agree that this appears to conflict with the language of 240.15, but the Code is not perfect.

 

[Smart $]

I disagree.

We are at an impasse...

You are reading something into the code which is simply not there.

On this part I will agree. My interpretation is aligned with what I believe is the intent of the code rather than the seemingly inexplicit wording of the Code.

 

[RUWired]

I think i can settle the disagreement quite easily. In Davids senerio he wants to have the transformer secondary conductors feed a receptacle device and have the primary OCPD protect the seondary conductors. His OCPD is protecting the transformer and he meets 240.21(C)2. BUT he does not meet the first provisions of 240.21 because he is supplying another conductor via the receptacle without OCP.

Rick

240.21 Location in Circuit.
Overcurrent protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (H). Conductors supplied under the provisions of 240.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.

 

[Smart $]

I think i can settle the disagreement quite easily. In Davids senerio he wants to have the transformer secondary conductors feed a receptacle device and have the primary OCPD protect the seondary conductors. His OCPD is protecting the transformer and he meets 240.21(C)2. BUT he does not meet the first provisions of 240.21 because he is supplying another conductor via the receptacle without OCP.

Rick

240.21 Location in Circuit.
Overcurrent protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (H). Conductors supplied under the provisions of 240.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.

His example was where the primary OCPD did not protect the secondary, and he was only qualifying the receptacle under 240.21(C)(2). I agree this settles the debate in that he cannot because of the second sentence of 240.21 general statement.

I had thought of this previously and forgot to bring it up because I believe he was only using the receptacle as an example device. As such, I feel the main disagreement is about connecting a secondary load device without qualifying primary protection and no secondary conductor protection.

David says he can, without secondary OCPD, under 240.21(C)(2). I say he can't. What say you (all)?

 

[david luchini]

I think i can settle the disagreement quite easily. In Davids senerio he wants to have the transformer secondary conductors feed a receptacle device and have the primary OCPD protect the seondary conductors. His OCPD is protecting the transformer and he meets 240.21(C)2. BUT he does not meet the first provisions of 240.21 because he is supplying another conductor via the receptacle without OCP.

Rick

240.21 Location in Circuit.
Overcurrent protection shall be provided in each ungrounded circuit conductor and shall be located at the point where the conductors receive their supply except as specified in 240.21(A) through (H). Conductors supplied under the provisions of 240.21(A) through (H) shall not supply another conductor except through an overcurrent protective device meeting the requirements of 240.4.

I had thought of that. 240.4 is for protection of conductors, not flexible cables and cords. That is covered under 240.5 (I think.) So my example would meet all of the requirements of 240.21.

My interpretation is aligned with what I believe is the intent of the code rather than the seemingly inexplicit wording of the Code.

That was also my interpretation also, until Charlie first raised the point that 240.21(C) didn't explicitly require OCP. Then I came to believe that if the intent of the code was to require OCP on secondaries (except under 240.21(C)(1)) then it WOULD NOT have included the language about terminating on a DEVICE.

 

[Volta]

...


That was also my interpretation also, until Charlie first raised the point that 240.21(C) didn't explicitly require OCP. Then I came to believe that if the intent of the code was to require OCP on secondaries (except under 240.21(C)(1)) then it WOULD NOT have included the language about terminating on a DEVICE.

Possibly, but as an OCPD is a device, maybe not.

 

[Smart $]

I had thought of that. 240.4 is for protection of conductors, not flexible cables and cords. That is covered under 240.5 (I think.) So my example would meet all of the requirements of 240.21.

While it is true the overcurrent provisions for cords and cables fall under 240.5, but as you follow those requirements they always refer back to the branch-circuit overcurrent device (in that the CMP assumes they are being fed by a branch circuit rather than a feeder or a secondary tap circuit), even when considered protected by a supplemental overcurrent device.

That was also my interpretation also, until Charlie first raised the point that 240.21(C) didn't explicitly require OCP. Then I came to believe that if the intent of the code was to require OCP on secondaries (except under 240.21(C)(1)) then it WOULD NOT have included the language about terminating on a DEVICE.

Possibly, but as an OCPD is a device, maybe not.

240.21(C)(2)(1)(b) refers to device and overcurrent protective device separately in the same sentence, so that condition does infer the device is something other than an OCPD.

However, as I said before, compliance under 240.21 other than the general statement is as specified in (A) through (H), and under 240.21(C) compliance is required with 240.21(C)(1) through (C)(6). It does not say one of (C)(1) through (C)(6), so an installation must comply with all of six. As such, unless precluded from requirements therein by text within each of the six conditions, it must comply with any that are applicable.

The above means that when secondary tap conductors are protected by the primary OCPD under 240.21(C)(1), they must also comply with 240.21(C)(2) because it is not render inapplicable by the text therein. (C)(3) through (C)(6) all require the secondary tap conductors to terminate at a single OCPD, so they are inapplicable.

Also note (C)(1) is about protection only, whereas (2) through (6) are about distance right up front in the title, and only then goes on about any required protection... but in the case of 240.21(C)(2)(1)(b) it is an "or" statement with "device" and "overcurrent protective" as the subjects. So as I said before, it is stated this way only to permit a 240.21(C)(1) installation of a device rather than an OCPD at the secondary tap conductors termination.

Note the preceding is a literal interpretation of the Code, and not one of intent.

 

[Volta]

...



240.21(C)(2)(1)(b) refers to device and overcurrent protective device separately in the same sentence, so that condition does infer the device is something other than an OCPD.

Yes, now that I am reading it :roll: I must agree.

And 240.21(C)(2)(2) would seem to disallow a receptacle, as the conductors may not extend beyond the disconnects or control devices they supply. That does seem to allow the use of the secondary conductors to supply multiple control devices, such as a contact in series with a coil. But not general utilization equipment.

 

[RUWired]

That does seem to allow the use of the secondary conductors to supply multiple control devices, such as a contact in series with a coil. But not general utilization equipment.

240.21 prevents the use of a contactor to supply anything without the use of OCP.

If you going to have utililizatioin equipment supplied by the secondary conductors such as resistive heat or motors, most likely 240.21(C)1 would apply.

Rick

 

[david luchini]

The above means that when secondary tap conductors are protected by the primary OCPD under 240.21(C)(1), they must also comply with 240.21(C)(2) because it is not render inapplicable by the text therein. (C)(3) through (C)(6) all require the secondary tap conductors to terminate at a single OCPD, so they are inapplicable.

So when the secondary conductors ARE protected by the primary OCPD as in 240.21(C)(1), they still MUST terminate on an OCPD or Device within 10' of the transformer secondary?

I don't believe that is the intent of the code. I don't read anything that would prevent the secondary conductors of a delta-delta transformer, protected by the primary OCPD, from running 100' or 1000'.

 

[david luchini]

And 240.21(C)(2)(2) would seem to disallow a receptacle, as the conductors may not extend beyond the disconnects or control devices they supply. T

The secondary conductors don't extend beyond the receptacle. They terminate at the receptacle, and go no further. A flexible cord or cable extends past the receptacle.

 

[Volta]

The secondary conductors don't extend beyond the receptacle. They terminate at the receptacle, and go no further. A flexible cord or cable extends past the receptacle.

The cord or cable contains conductors .

You would connect them to the secondary without OCPD.

They would be secondary conductors.

 

[david luchini]

And 240.21(C)(2)(2) would seem to disallow a receptacle, as the conductors may not extend beyond the disconnects or control devices they supply. That does seem to allow the use of the secondary conductors to supply multiple control devices, such as a contact in series with a coil. But not general utilization equipment.

The cord or cable contains conductors .

You would connect them to the secondary without OCPD.

They would be secondary conductors.

In that case, if I ran secondary conductors to an enclosed circuit breaker, and then extended a feeder from the enclosed circuit breaker to another device or panel, I'd be violating 240.21(C)(2)(2). The conductors "extend beyond" the device.

Yes, I am connecting them to the secondary without OCPD, because the code says I can. 240.21(C) says conductors can be connected to the secondary of a transformer, WITHOUT overcurrent protection in the secondary, as specified in 240.21(C)(1) through (C)(6). The conductors connected to the secondary run from the transformer to the device, but don't extend beyond it. Another set of conductors extending from the device would be required to have OCP in meeting the requirements of 240.4, but the requirements of 240.4 don't apply to flexible cords and cables.

 

[Volta]

In that case, if I ran secondary conductors to an enclosed circuit breaker, and then extended a feeder from the enclosed circuit breaker to another device or panel, I'd be violating 240.21(C)(2)(2). The conductors "extend beyond" the device.

Yes, I am connecting them to the secondary without OCPD, because the code says I can. 240.21(C) says conductors can be connected to the secondary of a transformer, WITHOUT overcurrent protection in the secondary, as specified in 240.21(C)(1) through (C)(6). The conductors connected to the secondary run from the transformer to the device, but don't extend beyond it. Another set of conductors extending from the device would be required to have OCP in meeting the requirements of 240.4, but the requirements of 240.4 don't apply to flexible cords and cables.

It does not say that. It says "...without overcurrent protection at the secondary..."

The secondary is part of the transformer. The OCPD is permitted by 240.21(C) to be located other than the point at which the secondary conductors receive their supply.

 

[Volta]

240.21 prevents the use of a contactor to supply anything without the use of OCP.

Section 240.21(C)(2)(2) implies that an unprotected secondary conductor may be allowed to feed control devices. A contactor qualifies as a control device, in my opinion.

If you going to have utililizatioin equipment supplied by the secondary conductors such as resistive heat or motors, most likely 240.21(C)1 would apply.

Rick

If one of the two type of allowed transformers, sure.

 

[david luchini]

It does not say that. It says "...without overcurrent protection at the secondary..."

Sorry, typing from memory, used the wrong word.

The secondary is part of the transformer. The OCPD is permitted by 240.21(C) to be located other than the point at which the secondary conductors receive their supply.

No, 240.21(C) permits conductors to be connected to the transformer secondary without overcurrent protection at the secondary, AS SPECIFIED in 240.21(C)(1) through (C)(6).

Some of the provisions of (C)(1) through (C)(6) require an OCPD to be located within 10', or 25' of conductor length, or unlimited conductor length for outside transformers, but the secondary conductors must terminate on an OCPD.

But 240.21(C)(2) PERMITS connection to either an OCPD or a DEVICE. It permits terminating secondary conductors (not more than 10' long) on a DEVICE without overcurrent protection. It doesn't say you are permitted to terminate on a device, as long as there is a secondary OCPD located somewhere else.

 

[Smart $]

So when the secondary conductors ARE protected by the primary OCPD as in 240.21(C)(1), they still MUST terminate on an OCPD or Device within 10' of the transformer secondary?

I don't believe that is the intent of the code. I don't read anything that would prevent the secondary conductors of a delta-delta transformer, protected by the primary OCPD, from running 100' or 1000'.

As I said, that is a literal interpretation of 240.21(C)(1) through (6)... i.e. completely disregarding any known or assumed intent.