Voltage Drop vs distance chart available?

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c2500

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I am wondering if there is a chart of some sort available that will give me wire size needed for varying amperages at a given distance. I am working in a warehouse and am hoping to avoid running alot of caculations. For example I need to place a 30A/240V receptacles at 250 from the panel. Then another at 230 feet and so on. Just hoping there may be a premade answer out there.

Thanks,

c2500
 
There on line calculators available, I doubt you will find a chart as there are to many variables.

A rough method is to bump up a size per 100'
 
Are these receps on the same circuit? And will they both be used at the same time? And what is the actual amperage draw [load] on the circuit (not the recep. rating)?
 
IMO voltage drop calcs are a worst case scenario. I fired up parking lot lights yesterday and my calcs said I would have 196V at the last 208V fixture. I have 204V there? Go figure.

This is not the first time I have noticed this.
 
chris kennedy said:
IMO voltage drop calcs are a worst case scenario. I fired up parking lot lights yesterday and my calcs said I would have 196V at the last 208V fixture. I have 204V there? Go figure.

This is not the first time I have noticed this.
Click to expand...
What was the voltage at the main? You may have started with 215 volts
instead of 208 volts.
 
chris kennedy said:
IMO voltage drop calcs are a worst case scenario. I fired up parking lot lights yesterday and my calcs said I would have 196V at the last 208V fixture. I have 204V there? Go figure.

This is not the first time I have noticed this.
Click to expand...

Many variables like starting actual voltage vs. nominal, actual load vs. name-plate, load distributed along the cicruit vs. at the end, etc.

source>>>>>>>middle>>>>>>>>end
208>>>>>>>>>>>>>>>>>>>>total load 196
208>>load>>>load>>>load>>>load>>>Last 204
Volts 208 207 206 205
Less load>>>>>>>>>>>>>>>>>>>>>Higher load
 
Fast way to do voltage drop

Fast way to do voltage drop

I don't know of any voltage drop charts but if you have to do a lot of voltage drop calculations then you might as well buy Electric Calc Pro. It is a very nice $100 dollar calculator that solves the voltage drop really easy and much more.:)
 
Has anyone else noticed how often,especially lately,that the Calculated Industries 'ElectriCalc' calculator gets brought up ?
Man those things must do it all,except pull the wire,the way they're all talking it up . JMO ... Think they should create a category just for the ElectriCalc's discussions ?

Carl
 
re: voltage drop

re: voltage drop

Although rather low tech in the American Electricians' Handbook (eleventh edition) in Division 11 page 80 (11-80) there is a good pictorial graph relating cooper conductor sizes for circuits according to voltage drop.
 
c2500 said:
I am wondering if there is a chart of some sort available that will give me wire size needed for varying amperages at a given distance.
Click to expand...
Perhaps this one will suffice. Still requires a little bit of calculating for specifc situation, but otherwise straight forward. This is also the method published in Ugly's Electrical Reference, as I recall.

Cooper Bussman Method (pdf)
 
bob said:
What was the voltage at the main? You may have started with 215 volts
instead of 208 volts.
Click to expand...

I'll be there again today. I'll get good numbers at both ends of all 4 circuits.

I use this:

VD=2xLxRxI?1000

L=one-way length in feet

R=resistance per 1000' fromm Chapter 9,Table 8

I=load amps

Anybody use this?

Voltage Drop Calculator JavaScript
 
chris kennedy said:
I'll be there again today. I'll get good numbers at both ends of all 4 circuits.

I use this:

VD=2xLxRxI?1000
Click to expand...
Aside from correction for actual voltage, that formula contains no adjustment for pf/reactance or ambient temperature.
 
sparkle5 said:
Although rather low tech in the American Electricians' Handbook (eleventh edition) in Division 11 page 80 (11-80) there is a good pictorial graph relating cooper conductor sizes for circuits according to voltage drop.
Click to expand...

sparkle5 ,
Since you have a version of "The American Electricians' Handbook" ,
would you consider it the electricians' bible as I've often heard it referred to as being ?

Carl :confused:
 
Smart $ said:
Aside from correction for actual voltage, that formula contains no adjustment for pf/reactance or ambient temperature.
Click to expand...
You figure power factor into I. In this case P/F was .85.(I use .9 when it's unknown)

I have 1800W of metal halide. 1800?208=8.65A. Actual load is 10A(all measurments taken with 2 Greenlee CM-850's). 8.65?.85=10.18A

Underground and concrete poles so ambient temp is a non-issue.

I couldn't get to the pole I wanted to because it was swarming with POed bees??? I took readings on the 2nd longest cir. and found this:

L=620' this includes wire up the poles
R=.491 #6 cu Chapter 9 Table 8
I=10A

VD= 2 x 0.491 x 620 x 10 ? 1000 = 6V

Actuall readings with a CM-850 at source and last head at the same time:

Source = 210V Furthest head = 206V

Difference between my calc and reality = 2V. Closer than I thought it would be.
 
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