Nace CP 1 - Page 37

Basic Electricity 1:14
CP 1 – Cathodic Protection Tester Course Manual
© NACE International, 2000
02/01/05
For example, consider the following circuit:
E
I
I
1
I
2
I
3
I
R
1
R
2
R
3
Figure 1.7 Parallel Circuit
I
T
= I
1
+ I
2
+ I
3
E
T
= I
1
R
1
= I
2
R
2
= I
3
R
3
321
T
R
1
R
1
R
1
1
R
++
=
1
T
R
E
I
1 =
2
T
2
R
E
I =
3
T
3
R
E
I =
Given E = 20 V
R
1
= 5 
R
2
= 4 
R
3
= 2 
IR
1
= E
T
= 20 V I
1
= E
T
/R
1
= 20 V/5 Ω = 4 A
IR
2
= E
T
= 20 V I
2
= E
T
/R
2
= 20 V/4 Ω = 5 A
IR
3
= E
T
= 20 V I
3
= E
T
/R
3
= 20 V/2 Ω = 10 A
I
T
= 4 A + 5 A + 10 A= 19 A