Tap rule help
- Thread starter majik009
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- Location
- Connecticut
- Occupation
- Engineer
Parallel 3/0 would be fine (assuming separate conduits.)
- Location
- Connecticut
- Occupation
- Engineer
Because the ampacity would be less than 400...using the adjustment factors for more than three current carrying conductors in a raceway.
majik009
Member
- Location
- Massachusetts
- Occupation
- Electrical Contractor
Its an interesting modification for sure
petersonra's earlier reply - "is it a tap or not" referrers to the actual definition of the conductors ? from the existing building main to the existing meter stack tap box (about 12' up over and down, away) via 3 sets of 90s on each side - i see these as feeders
I conclude yes we can employ a tap rule here , as we are not planning/hoping to extend all 3 sets of feeders from one meter section tap box to another
and if they terminate on a main cb for the stand alone new meter stack section then our one set of conductors should be protected ?
Bob
petersonra's earlier reply - "is it a tap or not" referrers to the actual definition of the conductors ? from the existing building main to the existing meter stack tap box (about 12' up over and down, away) via 3 sets of 90s on each side - i see these as feeders
I conclude yes we can employ a tap rule here , as we are not planning/hoping to extend all 3 sets of feeders from one meter section tap box to another
and if they terminate on a main cb for the stand alone new meter stack section then our one set of conductors should be protected ?
Bob
- Location
- Connecticut
- Occupation
- Engineer
Yes
- Location
- Connecticut
- Occupation
- Engineer
Yes, that is a feeder and you can use the feeder tap rules. You can't tap just one set of the conductors, however. You could use something like polaris multitap blocks to make the tap, or maybe you can add an additional lug to the bus in the meter bank tap box. The tap conductor ampacity must meet or exceed the rating of the main c/b on the standalone meter stack section.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
The only thing I may disagree on is the last sentence. If the meter stack section was "main lug". In that case it seems the wording in 240.21(B)(1)(1)(b) would allow it (Although the tap ampacity would need to be greater than that of the meter stack which would likely make it just a feeder continuation in practice).
- Location
- Connecticut
- Occupation
- Engineer
I'm not sure I follow. Maybe you missed that the OP said he would be terminating on a main c/b?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
I don't believe he said that. I believe the question was does he need over current protection.
- Location
- Connecticut
- Occupation
- Engineer
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Ok well that is not the OP, but irregardless (not a word), as an academic question, what are your thoughts about that wording and it's intent in 240.21(B)(1)(1)(b)?
- Location
- Connecticut
- Occupation
- Engineer
I think you mean disirregardless (actually heard someone say that once)
See post #7
The wording in all this is what's making this confusing.
First of all the "Tap" box in post #1 isn't actually a "Tap" box at all, It's actually a Main "Terminal" Box.
1200 amp evidently.
We never were told what the actual amperage of the new 4 stack group metering was going to be, or, what the size of the existing Feeder was to the existing Main Terminal Box and meters.
We're assuming a 1200a feeder to the existing and a 400 amp tap to the new.
With that being said, You're not "Tapping" the existing Tap Box as was stated in post #1, You're going to extend some wiring from the existing Main Terminal Box to feed a new one.
Depending on what size wire you use from the existing to the new is what's going to determine whether or not this is actually a "Tap" or not.
If you extend 1200a assumed wiring to the new group metering location, you haven't created a tap at all, You've simply extended a Feeder.
If you extend any wiring less than 1200 amps to the new location, then you are creation a "Tap" and need to follow the appropriate rule depending on the length and so forth.
Post #11 is a completely different scenario.
In that case a 1200 amp feeder is being "Tapped" with (3) individual 400 amp taps to (3) different locations.
As others have indicated, if you tap a 1200 feeder, you must originate the tap at a common point for each phase where they all come together, not tapping say 2 of the 3 parallel conductors by using a Polaris Terminal Blocks or additional lugs added to the bussing of the existing terminal box bus bars.
On a side note, I'd be leaning heavily towards the added lugs, and not the terminal blocks,,, just sayin.
JAP>
First of all the "Tap" box in post #1 isn't actually a "Tap" box at all, It's actually a Main "Terminal" Box.
1200 amp evidently.
We never were told what the actual amperage of the new 4 stack group metering was going to be, or, what the size of the existing Feeder was to the existing Main Terminal Box and meters.
We're assuming a 1200a feeder to the existing and a 400 amp tap to the new.
With that being said, You're not "Tapping" the existing Tap Box as was stated in post #1, You're going to extend some wiring from the existing Main Terminal Box to feed a new one.
Depending on what size wire you use from the existing to the new is what's going to determine whether or not this is actually a "Tap" or not.
If you extend 1200a assumed wiring to the new group metering location, you haven't created a tap at all, You've simply extended a Feeder.
If you extend any wiring less than 1200 amps to the new location, then you are creation a "Tap" and need to follow the appropriate rule depending on the length and so forth.
Post #11 is a completely different scenario.
In that case a 1200 amp feeder is being "Tapped" with (3) individual 400 amp taps to (3) different locations.
As others have indicated, if you tap a 1200 feeder, you must originate the tap at a common point for each phase where they all come together, not tapping say 2 of the 3 parallel conductors by using a Polaris Terminal Blocks or additional lugs added to the bussing of the existing terminal box bus bars.
On a side note, I'd be leaning heavily towards the added lugs, and not the terminal blocks,,, just sayin.
JAP>
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Nice! I'm going to have to try and use that sometime.
Ok I had to read that several times, its kinda confusing with the "or" and the double negative. I think you are saying the tap must terminate on an OCPD. IF so, how do you interpret the part in red? Couldnt that "device" be something like a meter stack? If not, what is this "device" they speak of and why the different language than in the 25' tap rule?
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