Line voltage taps under 600 volts

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Groundedforlife

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Cayuga, NY
Hey guys I've got another one for ya.

I'm running a single phase 208 volt underground circuit. Distance tells me to use #8 THHN. The eights
are going to underground enclosures. Then I will be tapping #12 branch circuits to pedestal mounted GFCI convenience receptacles using split bolts.
Is it prudent or code to fuse the 12 AWG wires. All wires will be in sch.40 pvc.

Thanks,
Groundedforlife
 
If you are using a 20 amp OCPD ahead of the #8 conductors then you have a splice and not a tap. Since the tap rules do not apply the use of an OCPD at the device would be optional.
 
infinity said:
If you are using a 20 amp OCPD ahead of the #8 conductors then you have a splice and not a tap. Since the tap rules do not apply the use of an OCPD at the device would be optional.
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you didnt answer the question ;) I dont see any branch circuit tap rule applying here, so you would either need to provide OCP for the 12's at the split, or OCP the whole mess at the #12 ampacity.
 
electrofelon said:
you didnt answer the question ;) I dont see any branch circuit tap rule applying here, so you would either need to provide OCP for the 12's at the split, or OCP the whole mess at the #12 ampacity.
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The OP referred to #12 branch circuits. By the code definition that either requires OCPD at the start of each #12 run OR the OP is using the word branch loosely.
In the first case the OCPD must be suitable for #12 or for the actual load.
In the second case the entire single branch circuit which includes the #8 must be protected at 20A.
 
THHN

THHN

Isn't THHN not allowed for underground?
I think THWN, RHHW or XHHW etc. is needed.
In other words a wire type that has a "W"
designator (I think)

JR
 
infinity said:
If you are using a 20 amp OCPD ahead of the #8 conductors then you have a splice and not a tap. Since the tap rules do not apply the use of an OCPD at the device would be optional.
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electrofelon said:
you didnt answer the question ;) I dont see any branch circuit tap rule applying here, so you would either need to provide OCP for the 12's at the split, or OCP the whole mess at the #12 ampacity.
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How so? If there is a 20 amp OCPD at the start of the circuit with the #8 conductors the entire circuit is protected at 20 amps. Then any portion of that circuit could be wired with #12's. :)
 
infinity said:
How so? If there is a 20 amp OCPD at the start of the circuit with the #8 conductors the entire circuit is protected at 20 amps. Then any portion of that circuit could be wired with #12's. :)
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And the #12 runs would not be "branches".
They would be parts of one branch circuit.
 
I failed code by doing this with with 20a in front of the #8s: inspector said next guy who came along and saw only my #8 wire on 20a protector might increase it to 40a not knowing about the downstream smaller wire.
 
mike_kilroy said:
I failed code by doing this with with 20a in front of the #8s: inspector said next guy who came along and saw only my #8 wire on 20a protector might increase it to 40a not knowing about the downstream smaller wire.
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It sounds like the same inspector would have to prohibit oversizing conductors to limit VD since someone might change the breaker and add load causing excessive VD. :)
 
mike_kilroy said:
I failed code by doing this with with 20a in front of the #8s: inspector said next guy who came along and saw only my #8 wire on 20a protector might increase it to 40a not knowing about the downstream smaller wire.
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Then you could say it was supplying a 16 amp motor load. Would that work ?
 
mike_kilroy said:
I failed code by doing this with with 20a in front of the #8s: inspector said next guy who came along and saw only my #8 wire on 20a protector might increase it to 40a not knowing about the downstream smaller wire.
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Does code address putting larger wire on smaller breaker labeling or anything from preventing someone installing a larger breaker ?

Seams like most things like grouping for multi wire branch circs.

Hand ties. Label this and that.

Strange that isn't addressed . ( guess if there's a panel directory or common sense might be able to figure it out ) but
 
electrofelon said:
Just that my interpretation of the OP was that he was looking to use a tap rule and have the 8's protected over 20......
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But the OP makes no mention of OCPD.
Just having a limited load is not good enough.
And if using OCPD only physical configuration would prevent having it at the branching point, making it not a tap.
 
mike_kilroy said:
I failed code by doing this with with 20a in front of the #8s: inspector said next guy who came along and saw only my #8 wire on 20a protector might increase it to 40a not knowing about the downstream smaller wire.
Click to expand...

That inspector needs a refresher course. :roll:
 
GoldDigger said:
But the OP makes no mention of OCPD.
Just having a limited load is not good enough.
And if using OCPD only physical configuration would prevent having it at the branching point, making it not a tap.
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He uses the word "tap" twice. By definition, a tap is a lowering of wire size relative to the OCPD. Of course he may have been using "tap" in the general sense of just "splicing". He did say "for distance" but he also mentioned multiple outlets so it could be reasonable to asssume that he wants more than 20 amps.
 
infinity said:
That inspector needs a refresher course. :roll:
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He made me replace the oversized run, put in to reduce VD, with same #12. Actually it made sense to me; no telling if someday someone else just opened the breaker box and saw #8 on 20 amp breaker and assumed they could replace it with 40 amp; maybe I should have been allowed to make a note there was #12 downstream; but a note could fall off? Maybe he had OCPD too (Obsessive-compulsive personality disorder). Seems only proper way for OP is to put 20a protection devices at the end of #8 run.
 
electrofelon said:
He uses the word "tap" twice. By definition, a tap is a lowering of wire size relative to the OCPD. Of course he may have been using "tap" in the general sense of just "splicing". He did say "for distance" but he also mentioned multiple outlets so it could be reasonable to asssume that he wants more than 20 amps.
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NEC does not have a definition for the word "tap". In 240.21 NEC does use the words "branch circuit tap conductors" and "feeder taps", but doesn't give a specific definition for those terms, though the sections those terms are used in do kind of describe each situation fairly well. I think most any place else in the code that deals with such situations does reference 240.21 and requires that situation to also comply with 240.21.

Otherwise just field talk and the word "tap" can be confusing at times to what the intent was of the person that used that term.
Webster-Merriam online dictionary gives us this definition for tap as it relates to electrical applications:
"an intermediate point in an electric circuit where a connection may be made"
so without any other context as is in 240.21 any junction point could be considered a tap whether there is a change in conductor size or not.

mike_kilroy said:
He made me replace the oversized run, put in to reduce VD, with same #12. Actually it made sense to me; no telling if someday someone else just opened the breaker box and saw #8 on 20 amp breaker and assumed they could replace it with 40 amp; maybe I should have been allowed to make a note there was #12 downstream; but a note could fall off? Maybe he had OCPD too (Obsessive-compulsive personality disorder). Seems only proper way for OP is to put 20a protection devices at the end of #8 run.
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There is no requirement to tag or otherwise identify such oversized conductors though nothing prohibits that either, your inspector needs to pull his head out of the sand, voltage drop is a real world problem and over sizing conductors is a way to deal with it.

If I wanted I can put 500 kcmil copper on a 15 amp overcurrent device and the only way it violates code is if I try to land it directly on a device that wasn't designed to accept that size of conductor (which would be typical for a 15 amp device)
 
kwired said:
NEC does not have a definition for the word "tap".
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what about this one?

240.2
Tap Conductors. As used in this article, a tap conductor is
defined as a conductor, other than a service conductor, that
has overcurrent protection ahead of its point of supply that
exceeds the value permitted for similar conductors that are
protected as described elsewhere in 240.4.
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granted it does not define the word "tap".
 
petersonra said:
what about this one?



granted it does not define the word "tap".
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I knew I should have looked harder;)

But, that definition is in the .2 part of a particular section as well as it actually says " As used in this article" making it only apply to the article it is associated with and not a general term that has same definition throughout the entire code, if it were that it would be in art 100.

I guess OP's situation is still dealing with overcurrent protection issues so it still applies, But OP's conductors do not have an ampacity that is less then the overcurrent device setting either so still no problem with his install. For it to be a "tap" by that definition conductor must have ampacity less then the overcurrent protection (other then where next standard size up rule applies)
 
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