VD

Status
Not open for further replies.
A

Alwayslearningelec

Senior Member
Location
NJ
Occupation
Estimator
So I have some 20A 120v receptacles that are about 150-200' away from panel.
About 20 of them on more than a few circuits,
I don't think 12/2 mc cable( for each circuit) would work due to voltage drop.
A few questions.
1. I think it would make more sense to run pipe and wire to the are the drop down with MC from there. I know I need to consider derating for # of ccc's.
2. If one was to run MC from the location to a box near the panel( about 150'-200' away) what size cable? I ran a calc and came up with #8's. I don;t think that's right.

THanks.
 
ptonsparky said:
I would be inclined to run a feeder to the area but you will need to have some idea as to the loads involved to determine VD. Also inclined to oversize the feeder, just because. Budget constraints will be your issue to deal with.
Click to expand...

I agree, and for voltage drop it could be best to run a 3-wire feeder for split-phase, or a 4-wire if it's 3-phase.
 
Ok and agree. How about if one was to use mc cable from the receptacle( 1 circuit) to the power source 150-200' away. #12 would not work, correct?
 
horsegoer said:
Ok and agree. How about if one was to use mc cable from the receptacle( 1 circuit) to the power source 150-200' away. #12 would not work, correct?
Click to expand...
You can run #8 or #10 MC to the first receptacle and then #12's from there. Given that you need several circuits I would just run a single run of EMT and then branch out from there with MC.
 
infinity said:
You can run #8 or #10 MC to the first receptacle and then #12's from there. Given that you need several circuits I would just run a single run of EMT and then branch out from there with MC.
Click to expand...
Right I got that. but trying to determine what footage 10/2 mc would be good for from receptacle to near panel if we were to do that.
I think the conduit would be better idea.
BTW can you land #8 on receptacle?
 
wwhitney said:
Southwire's calculator disagrees by around a factor of two. It gives 6.5% for #12 and 1.1% for #4.

Cheers, Wayne
Click to expand...
I used the Southwire calculator. FOr the input " current at end of cable" what would one put? The OCPD rating?
In this situation 20a breaker feeding the receptacles.
 
horsegoer said:
So for receptacles one doesn't really know the load....what would I enter? A set value for each receptacle and add that up?
Click to expand...
You need to know the load. You could ask the specifier/user what they want.

If you want to cover the worst case that someone is going to plug in (2) 10A resistive heaters on a single 20A branch circuit, then you need to use 20A as your load.

On the other hand, loads that will draw 20A might often be tolerant of more voltage drop than the typical spec of 2% or 3%. (As a resistive heater would be.) So it might be reasonable to design for 2% at 10A and accept that would mean 4% at 20A.

Cheers, Wayne
 
Status
Not open for further replies.
Top