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Location of Feeder Tap

Yes, it has to be within a given distance of the OCPD supplied by the feeder tap, as per the section of 240.21(B) under which the tap is permitted.

Cheers, Wayne
 
jar546 said:
The tap shall be permitted at any point on the load side of the feeder overcurrent protective device.
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The above is open to misinterpretation. We've got a few different variables here--location of the feeder OCPD, location of the OCPD supplied by the tap, and location of the tap.

It's true that generically there's no restriction on where the tap can be on the load side of the feeder OCPD, it can even be on the feeder OCPD load side lugs. But it's also true the length of the tap conductors is limited by several of the options in 240.21(B), in which case the location of the tap is limited with respect to the location of the OCPD supplied by the tap.

Cheers, Wayne
 
jar546 said:
Yes, I agree. The discussion was never about the length or size of the tap conductors themselves.
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Yet clearly the location of the tap is one of the variables that determines the length of the tap conductors, and as the length of the tap conductors is typically constrained, that translates into a possible constraint on the tap location. It's simple geometry.

Cheers, Wayne
 
wwhitney said:
Yet clearly the location of the tap is one of the variables that determines the length of the tap conductors, and as the length of the tap conductors is typically constrained, that translates into a possible constraint on the tap location. It's simple geometry.

Cheers, Wayne
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Please give us a specific example of where the location of the tap to a feeder is limited in location. I will provide an example and you can explain where the tap location is limited to.

1) A 277/480v 1200A MDP feeds a 200A panelboard (P1) 120' away in a warehouse. The feeder starts with a 200A OCPD in the MDP and uses 250MCM cu to the said panelboard (P1). There are no more open OCPD spaces in the MDP, but the load calcs shows it is only at 50% capacity & P1 is only at 25% capacity. The electrician wants to tap off of the 120' long 250MCM cu feeder to run a new extruding machine. The extrusion machine requires a 60A OCPD, and the electrician plans to tap it with #4awc cu. The plan is to install a junction box at the tap location of choice.

A) If the 277/480v 60A fuseable disconnect is 8' from the tap location, where is the tap location limited to?

B) If the 277/480v 60A fuseable disconnect is 22' from the tap location, where is the tap location limited to?
 
jar546 said:
Please give us a specific example of where the location of the tap to a feeder is limited in location.
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OK I'll draw something up, but first let me just put my point this way:

If the OP said "Does it matter where I tap the load side of a feeder, in relation to the location of the feeder OCPD?" then the answer would be no, as per your post #3.

Whereas if the OP said "Does it matter where I tap the load side of a feeder, in relation to the location of the OCPD supplied by the tap?" then the answer would be yes, as per post #2.

Cheers, Wayne
 
wwhitney said:
OK I'll draw something up
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Here's my fairly basic drawing. The existing panels and feeder are in black. The location of the new equipment is fixed by the customer's needs. The location of the new disconnect is fixed by needing to be in line of sight of the new equipment, which per the NEC definition limits it to 50' away. The customer doesn't want a second disconnect.

If this is indoors, and conductor and OCPD sizes require the permissions of 240.21(C)(1), the 10' tap rule, then the tap has to be at that central red point.

If this is indoors, and conductor and OCPD sizes meet the limits of 240.21(C)(2), the 25' tap rule, then the tap can be anyway between the two outer red points

And lastly, if the existing feeder and panels are outdoors, while the new disconnect is on the interior face of an exterior wall, with the tap conductors entering the back of the new disconnect directly, then per 240.21(C)(5), the outdoor tap rule, the tap can be anywhere on the existing feeder.

Cheers, Wayne

Example.jpg
 
wwhitney said:
Here's my fairly basic drawing.
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Oh, I forgot to mention one more customer requirement, no diagonal conductor conductor runs. [That's just to keep the math simpler.] The "10' of run" figure already includes any necessary contribution from the vertical dimension not shown in the drawing.

Cheers, Wayne
 
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