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The answer to this question is simply ohms law. For most cables the resistance of the cable per meter will be defined by the manufacturer, so firstly multiply this by the length of the cable you are using.
Then apply ohms law V=IR. This will give you the voltage drop across the cable.
In most cases for domestic use, this value of R is so small the voltage drop is negligble, though using a cable with the lowest value R will give you the lowest voltage drop for any application.
If you're referring to a voltage drop in an Electrical Network the calculation becomes abit more complex and involves solving some implicit and explicit equations (assuming you know the voltage and power factor at the sending end and the real and complex powers consumed at the receiving end). If you wish to know more about this calculation let me know.
THIS CONSIDERATIONS SHOULD BE STRICKLY FOLLOWED: SOUND ENGINEERING AND ACCEPTABLE ECONOMICS;
1.DEFINE DEMAND LOAD - AFTER APPLYNG POWER FACTOR AND EFFECIENCY FOR MOTOR LOADS AND ACTUAL SYSTEM VOLTAGE AND PHASE.
2. ONE WAY LENGTH OF WIRE OR CABLE - FT. (AWG) OR MTR. (SQ.MM) SELECTION
3. MULTIPLY BY 125% TO THE CALCULATED LINE CURRENT TO GET AMPACITY REFERENCE
4. LOOK OR SELECT THAT NEAREST RESULT TO ANY LOCAL CABLE SUPPLIER CATALOGUE OR NEC TABLES AND MATCH IT TO CORRESPONDING CABLE SIZE.
5. APPLY DERATING FACTORS - ALSO AVAILABLE TO NEC OR CABLE SUPPLIERS AND DEFINE THE FF:
A. MEDIUM OF INSTALLATION - PVC OR RSC CONDUIT, CABLE TRAY OR CABLE LADDER OR TRUNKING, THROUGH, ETC.
B. AMBIENT TEMPERATURE - INDOOR OR OUTDOOR?
C. GROUP FACTOR - CONSIST OF CABLE SPACING AND DISTANCE TO WALL OR INSIDE CONDUIT INSTALLED IN TRAYS OR UNDERGROUND
6. APPLY DERATION IN WHICH RESULT IS LESS THAN ONE (1) TO THE PRE-SELECTED CABLE - THIS IS NOW YOUR ACTUAL FOR SELECTED CABLE
7. DEFINE REQUIRED OR ACCEPTED VOLTAGE DROP IN PERCENT VALUE
8. NOW USE THIS FORMULA:
VDapp(APPLICABLE VOLTAGE DROP) = %Voltage Drop x Actual Voltage x 1000 divided by Derated Current x One Way Length x 100
9. THE RESULT WILL HAVE A UNIT OF -- mV/A.Mtr OR MILLIVOLT PER AMPERE-METER
10. NOW COMPARE IT TO AVAILABLE TABLES FOR VOLTAGE DROPS OF CABLES - IF IT IS LOWER THEN SELECT THE NEXT SIZE OR WHICH EVER MEET THE REQUIREMENT.
you'll need to know the resistance of the conductor. copper has a certain amount of resistance per length. there are charts available on this
Wiki User
∙ 12y ago
Wiki User
∙ 10y agoThe formula to calculate cable size and voltage drop is Vdrop = current x distance times 2 times Ohms per 1000ft times 0.001.
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How do you calculate the cable size for a run of 30 meters?
to calculate the cable size of a run of 30 meters long you first will have to know the current of the appliance use the voltage drop formula V d = (mVxIxL)/1000 once the voltage drop is less than 2.5% of the nominal voltage, the cable should be upsize.
What effect does it have on the voltage drop in an electrical cable if the resistance of the cable is decreased?
It will decrease the voltage drop.
Will voltage drop over cable distance?
If the voltage is supplying any current through the cable, i.e. if there is any 'load' at the end, then the voltage will drop through the cable.
Why drop voltage in xlpe cable is more than PVC cable?
The voltage drop in a wire has nothing to do with the insulation. Voltage drop has to do with the cross sectional area of the wire.
What would the cable size be for a 90 meter armoured cable with a 110 amp supply with a 330 amp start up?
To calculate voltage drop to size the wire, a voltage must be stated.
How do you find cross sectional area of cable when you have the lent current and the voltage drop?
cross sectional area of cable * voltage drop
What is voltage drop when utilized with cable runs?
A: ANY CABLE will have a definite impedance and if current flow there is going to be a definite voltage drop because of it
How do you calculate voltage drop for starting motor current and how to get the starting pf?
How do you calculate voltage drop for starting motor current
How do you calculate voltage drop in a parallel circuit?
The formula for a simple DC voltage drop across a cable is:VDrop = Vmeasured at the input of cable - Vmeasured at the output of cableThis formula may seem simplistic however keep in mind that the sensitivity, accuracy and resolution of measuring instrument instrument is what is really important.If you know the DC current flowing through the cable and the impedance of the cable then you can use Ohm's law. Vdrop = I R where Vdrop is the voltage drop across the cable in volts I is the current flowing through the cable in amperes R is the resistance of the cable in ohms.ADDITIONALCalculation of the voltage drop is given by the formula belowVoltage Drop (Volt) = [(mV/Am)/1000] * I * lWhere mV/Am = millivolt drop per meter per ampere of the cable(this information is given in the table based on IEE Wiring Regulation)I = Current in the cable (in Ampere)l = Distance of cable (in Metre)See related links below
What is the voltage drop for 16 mm Cable over 100 meters?
The voltage drop depends on the current through the cable.For DC current in cable of 16 mm diameter, at 68° F, the voltage drop is(0.00857) x (current, Amperes) volts.
Is it okay to use thicker cable to avoid voltage drop?
It is mandatory to use a larger wire size to overcome voltage drop at the load.
How do calculate voltage drop in a circuit?
for calculating the voltage drop in ckt first of all you have to calculate the total resistance of the ckt as well as total current also then applying ohm's law v=IR u can calculate the voltage drop across a ckt While the answer is correct you might investigate thevenin theory.
