Maximum homeruns

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satcom

Senior Member
what is the maximum homeruns in one 3/4" conduit? The circuits are powering 20a receptacles.


The best answer is sit down relax and open up your code book, and look at all the tables and then read the foot notes with care.
Type of conduit? and conditions it will be installed in? type of wire? size
 
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Dennis Alwon

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Location
Chapel Hill, NC
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Retired Electrical Contractor
what is the maximum homeruns in one 3/4" conduit? The circuits are powering 20a receptacles.

This would be hard to answer for a few reasons. First, there are tables in the back of the book in Chapter 9 that tell you how many wires would fit in different conduits. EMT may be different from PVC, etc.

Once you get over 3 wires you must derate and it could be possible that a larger size wire would be needed.
 

gardiner

Senior Member
Location
Canada
If you don?t mind I have a question on the way this question is worded in a way that may be a little different then normal, not how many wires in a 3/4 inch conduit but how many homeruns. The term homeruns can mean the entire grouping for a circuit as one homerun which would mean the answer would be different if it was a situation where you were running an independent neutral with each circuit or if the circuits were sharing neutrals. Exactly what are you trying to do?
 

don_resqcapt19

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Location
Illinois
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retired electrician
Are you asking about the derating of the conductors? If so, then in general, there is no issue for 15 and 20 amp branch circuits until you exceed 9 current carrying conductors in the raceway.
 
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satcom

Senior Member
If you don?t mind I have a question on the way this question is worded in a way that may be a little different then normal, not how many wires in a 3/4 inch conduit but how many homeruns. The term homeruns can mean the entire grouping for a circuit as one homerun which would mean the answer would be different if it was a situation where you were running an independent neutral with each circuit or if the circuits were sharing neutrals. Exactly what are you trying to do?


And if he had 277V or was loading with inductive loads, the answers will be different.
 

Cavie

Senior Member
Location
SW Florida
The number of home runs is irrelevant to the problem. # of conductors in the conduit is the problem no matter where it's going.
 

satcom

Senior Member
I think we just want the OP to understand, there is more to running conductors in conduit, then just how many.
 

kwired

Electron manager
Location
NE Nebraska
what is the maximum homeruns in one 3/4" conduit? The circuits are powering 20a receptacles.

most of the time 40% of the cross sectional area of the raceway.

you would also need to know what size conductors will be required and what the cross sectional area of the conductors is
 

rt66electric

Senior Member
Location
Oklahoma
rule of thumb

rule of thumb

I have been informed my many a seasoned hand-----6 hots in a 3/4------3 hots in a 1/2--- I have never seen a blow-out in the middle of a conduit run due to insuffient derating: however I have seen a few blowouts due to insuffient pipe reaming, or other factors...
 

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
Ah, can I actually shed some light on a question....whoo hoo.....a homerun can consist of any different number of circuits thus have different quantity of wires. The numbers of wire is what is needed. We usually run 6 circuit homeruns but lately the specs have been limited homeruns to 3 circuits.
 

Cold Fusion

Senior Member
Location
way north
It said Electrical Engineer in your profile, think what happens when you put conductors feeding a bank of ballast in a metal conduit.
Hummm ... I'll make a couple of assumptions:
1. By "metalic", you mean "ferrous".
2. The conductors are installed per NEC - all the circuit conductors are in the same raceway.

So, is the answer, "The conductors warm up porportional to the current loading - same as if they were in a non-ferrous conduit?"

cf
 

satcom

Senior Member
Hummm ... I'll make a couple of assumptions:
1. By "metalic", you mean "ferrous".
2. The conductors are installed per NEC - all the circuit conductors are in the same raceway.

So, is the answer, "The conductors warm up porportional to the current loading - same as if they were in a non-ferrous conduit?"

cf

We derate the conduit to reduce problems from the effect of heating, all conduits are enclosing the conductors, and in metal conduits, we have the additional effect of not just current loading, but also the added effect of induced induction loads, and these loads can, if not derated, reach a temp hot enough to cook an egg.

It would be nice for the OP the read up and learn as much as he can about derating, it is not a cut and dried, read the table. and just do it issue.
 

Cold Fusion

Senior Member
Location
way north
We derate the conduit to reduce problems from the effect of heating, all conduits are enclosing the conductors, and in metal conduits, we have the additional effect of not just current loading, but also the added effect of induced induction loads, and these loads can, if not derated, reach a temp hot enough to cook an egg. ...
This is the part I don't get. You're using some physics I've never heard of before.

What is an "induced induction load"?

cf
 
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