500mcm

[frank melillo]

how meany 500mcm can go into 3.5 inch conduit

 

[Dennis Alwon]

how meany 500mcm can go into 3.5 inch conduit

What type conduit? & what type insulation

 

[wbalsam1]

how meany 500mcm can go into 3.5 inch conduit

Try this: Chapter 9 Tables, Table #5 for conductor choices, and Table #4 for conduit choices.

 

[frank melillo]

500mcm

the type of wire is thhn

 

[infinity]

500 kcmil THHN in 3.5":

EMT=6

FMC=5

IMC=6

RMC=5

PVC Sch 80=5

PVC Sch 40=5

 

[iwire]

Frank, now you can see why Dennis asked for both insulation and raceway type.

 

[Dennis Alwon]

Go to table 4--- Conduit type-- If you are using PVC then the sq. in is 3.895 for 3 1/2" conduit.

Go to table 5 for 500 mcm thhn and the sq. in is .7073

now divide 3.895/.7073= 5.5

you can get 5 500 mcm THHN cables in 3.5 PVC

 

[iwire]

Dennis with all the same size conductors how about using Annex C?

 

[frank melillo]

500mcm

sorry not to give all the info i had three phones in ear when asking.
thank to all for you help.
this question forum is great

 

[Dennis Alwon]

Dennis with all the same size conductors how about using Annex C?

Yes-- I wanted to show how to calculated it for future references for the OP.

 

[Dennis Alwon]

You know I always hated using Annex C because it took so long to find the correct page. I just realized that the first page (which I must of missed all these years) has an index--- much easier.

 

[chris kennedy]

Dennis with all the same size conductors how about using Annex C?

I guess we won't ask OP if theres a EGC involved.

 

[George Stolz]

I cheat. I have the EMT table (Annex C.1) on my palm pilot, saves papercuts.

View attachment 570​

 

[chris kennedy]

I'm with Dennis on this. It's a very quick and easy calc. And 90% of the time I have an EGC.

 

[ty]

saves papercuts.

How's this for a papercut?
Stitches and tape to hold end of thumb on:

 

[LarryFine]

I cheat, too. I use this: http://jlgengsoft.com/Documents/fill.htm

Added: Ty: ouch!

 

[iwire]

And 90% of the time I have an EGC.

I usually carry an EGC as well.

That said I bet 90% of the runs we have to figure have the same size EGC as the circuit conductors.

Once we get into larger circuits the plans usually have a conduit size indicated.

I agree it is not a 'hard calculation' but a table is faster.

 

[chris kennedy]

Once we get into larger circuits the plans usually have a conduit size indicated.

Bob, On all large jobs I double check ampacity, EGC sizing, conduit size and load calcs. I'll only find a couple of mistakes a year but a common one is under sized EGC. So correct that and now you find you have .003 in.2 left in a 200' run. More soap or next size up?

 

[iwire]

Bob, On all large jobs I double check ampacity, EGC sizing, conduit size and load calcs.

I will never say always.

Ampacity: I will check if something seems out of whack.

EGC: I will check if something seems out of whack.

Conduit size: I will check if something seems out of whack.

Load Calcs: Never, that is definitely the engineers issue as far as I am concerned.

How can I 'check' load calcs? I will have no idea the method they used to arrive at their answers.

So correct that and now you find you have .003 in.2 left in a 200' run. More soap or next size up?

I have no problem using a code minimum size conduit in some instances.

The size of the conduit does not change the pulling tension assuming the conduit is at least code minimum.

I had a 1,600 amp feeder to run specified as five sets of 500 kcmil XHHW + grd in five - 4" RMC. I did the math and got approved to run five sets of 3" EMT instead. The run had to go above an existing crowded suspended ceiling, I needed it as compact as I could get away with.

and yes.....we used a lot of soap.

On the other hand PVC underground we will usually go bigger than needed.