3 phase distribution

[Apower3000]

Am running two 500 parallel feeder (3 phases + Neutral + Gnd) and at one point they need to be spliced to one 350 feeder, so the connection would be every 2/C-#500 get spliced to 1/C-#350, the problem am having if I need to do the splice for the 3 phases and Neutral I will need kind of big enclosure so one suggestion was to put them in separate small boxes. Is there any code violation if splice three phase + Neutral not within the same enclosure.

 

[Smart $]

Am running two 500 parallel feeder (3 phases + Neutral + Gnd) and at one point they need to be spliced to one 350 feeder, so the connection would be every 2/C-#500 get spliced to 1/C-#350, the problem am having if I need to do the splice for the 3 phases and Neutral I will need kind of big enclosure so one suggestion was to put them in separate small boxes. Is there any code violation if splice three phase + Neutral not within the same enclosure.

I don't see how you can do that and comply with 300.3(B) Conductors of the Same Circuit and as modified by (B)(1)Parallel Installation.

 

[kwired]

If you are running parallel 500's you should have a fairly large box in the first place. Addition of the 350's into same box will also increase the minimum allowed size for the box. Wouldn't it cost less to make the box a little bigger if necessary than to use two boxes?

What are you splicing 350's onto 500's for? Feeder taps? Make sure you connect taps to both (or all if more than two) feeder conductors and not just to one of them, otherwise you are not following the parallel conductor rules properly.

 

[elec_eng]

pWhat are you splicing 350's onto 500's for? Feeder taps? Make sure you connect taps to both (or all if more than two) feeder conductors and not just to one of them, otherwise you are not following the parallel conductor rules properly.

Kwired,

What parallel conductor rule are you refering to? Which code section requires that you have to tap all parallel conductors?

 

[kwired]

Kwired,

What parallel conductor rule are you refering to? Which code section requires that you have to tap all parallel conductors?

310.4 is a place to start that has most of what applies.

The purpose of using conductors in parallel is to make multiple coductors effectively one conductor. If not joined at both ends this does never happen. If you make a tap in the middle of the effectively larger conductor but only connect the tap to half , or third, or fourth, etc of the effectively larger conductor you have disrupted the whole purpose of calling this one conductor as you throw off the load balance on the set. If you tie all conductors of the parallel together where making a tap then you are taping the whole conductor and not just part of it.

Take our two 500's in parallel in this thread.

500 has an ampacity of 380 @ 75 deg C.

Parallel two of them you effectively have a 760 amp conductor.

Make a tap off of one of them you are not taping a 760 amp conductor you are taping a 380 amp conductor.

This also creates another problem because that single 500 is not protected at its ampacity it is protected at the parallel conductor ampacity making it a tap conductor itself. You can not tap a tap either.

 

[masterinbama]

I would use a section of wireway and and either these,

http://www.ilsco.com/ProductsDetail...=Q/aOLKHyW/oPH7LkpNGycCyflIq7eXk3FrVCsYL8FTw=

or these

http://www.ilsco.com/ProductsDetail...=PwsKCWwZ4OvNxibvLkwWSFr4VOyYmnLO8irUEYFlgvc=

 

[elec_eng]

310.4 is a place to start that has most of what applies.

The purpose of using conductors in parallel is to make multiple coductors effectively one conductor. If not joined at both ends this does never happen. If you make a tap in the middle of the effectively larger conductor but only connect the tap to half , or third, or fourth, etc of the effectively larger conductor you have disrupted the whole purpose of calling this one conductor as you throw off the load balance on the set. If you tie all conductors of the parallel together where making a tap then you are taping the whole conductor and not just part of it.

Take our two 500's in parallel in this thread.

500 has an ampacity of 380 @ 75 deg C.

Parallel two of them you effectively have a 760 amp conductor.

Make a tap off of one of them you are not taping a 760 amp conductor you are taping a 380 amp conductor.

This also creates another problem because that single 500 is not protected at its ampacity it is protected at the parallel conductor ampacity making it a tap conductor itself. You can not tap a tap either.

kwired,

Thanks for the insight. That makes sense. However, if I had to cite a code violation, what sections I have to use to prevent this? 310.4 doesn't clearly layout the requirements the way you do.

 

[elec_eng]

kwired,

Thanks for the insight. That makes sense. However, if I had to cite a code violation, what sections I have to use to prevent this? 310.4 doesn't clearly layout the requirements the way you do.

Anyone else can provide the code reference?

 

[david]

Anyone else can provide the code reference?

240.21 Location in Circuit.

 

[kwired]

kwired,

Thanks for the insight. That makes sense. However, if I had to cite a code violation, what sections I have to use to prevent this? 310.4 doesn't clearly layout the requirements the way you do.

I guess I would cite 310.4 and/or 240.21. If the feeder is 800 amps then you are taping the feeder which is all sets that make up the feeder. If you don't tap to all sets that make up the feeder then what you tapped onto is a tap itself by definition.