Purpose for parallel runs

[eager2learn]

Whats the purpose for parallel runs? Does it have to do with amperage? Secondary side of transformer has two parallel feeder runs feeding a distribution panel.

 

[Dennis Alwon]

Usually you would run parallel feeds when the conductors get too large to handle. Too smaller conductors are easier to deal with then one larger one. In some situation the amps needed is higher than any one conductor. Think about 2000 amp services--

So yes double the wire and you double the amps-- remember in most cases you cannot parallel smaller than 1/0

 

[Rockyd]

See art. 300.3(B)(1), and all of the places to go check...

 

[Besoeker]

Usually you would run parallel feeds when the conductors get too large to handle. Too smaller conductors are easier to deal with then one larger one. In some situation the amps needed is higher than any one conductor. Think about 2000 amp services--

So yes double the wire and you double the amps-- remember in most cases you cannot parallel smaller than 1/0

All other tings being equal, you can usually get more current from the same conductor area with two smaller conductors - more surface area to dissipate the heat.

 

[Crionics]

Also, keep in mind that your each EGC in the parallel feeds must be sized for the OCP device...

 

[wireman]

In addition to what the others have said, another reason is if one large conduit is too big to run concealed in a wall you can run two or more smaller conduits.

 

[iwire]

All other tings being equal, you can usually get more current from the same conductor area with two smaller conductors - more surface area to dissipate the heat.

I agree 100%.

For example a 100' long 3 phase 4 wire, 400 amp feeder in copper

1 set of 600 Kcmil copper $3,057*

2 sets of 3/0 copper $2,200*

(* July pricing, EGC not included)

Of course you do have to consider how much an extra raceway and labor will be but if you are using PVC the savings are pretty good.

 

[masterinbama]

I agree 100%.

For example a 100' long 3 phase 4 wire, 400 amp feeder in copper

1 set of 600 Kcmil copper $3,057*

2 sets of 3/0 copper $2,200*

(* July pricing, EGC not included)

Of course you do have to consider how much an extra raceway and labor will be but if you are using PVC the savings are pretty good.

3" EMT is double what 2" is. Your labor difference per 100' is negligible.If you add a ground wire instead of using the conduit a 3.5" is required.

$180 per hundred for 2"

$390 per hundred for3"