Advanced Marine Electrics and Electronics Troubleshooting A Manual for Boatowners and Marine Technicians

that if the circuit is protected by a GFCI
(ground fault circuit interrupter) or a GFP
(ground fault protection) device, the device
will trip during this test. Simply reset it after
you’ve acquired the values.
Use Table 4-3 to help you troubleshoot
impedance problems.

testing ac and grounding systems 53

Expected Possible Possible

Measurement Result Problem Causes Solutions

Voltage drop < 5% High voltage Too much load on the Redistribute the load on the

drop circuit. circuit.

Undersized wire for length Check code requirements

of run. and rewire if necessary.

High-resistance connection Locate high-resistance

within the circuit or at connection/device and

the panel. repair/replace.

Source:Ideal Industries, Inc.

Voltage Drop Troubleshooting Tips

TABLE

4-2

Expected Possible Possible

Measurement Result Problem Causes Solutions

Hot and neutral < 0.048 /foot High conductor Too much load on Redistribute the load on the

impedance of 14 AWG wire impedance branch circuit. circuit.

< 0.03 /foot of Undersized wire for Check code requirements

12 AWG wire length of run. and rewire if necessary.

< 0.01 /foot of High-resistance Locate high-resistance

10 AWG wire connection within the connection/device and

circuit or at the panel. repair/replace.

Ground < 1 to protect High ground Undersized wire for Check code requirements

impedance people impedance length of run. and rewire if necessary.

< 0.25 to High-resistance Locate high-resistance

protect equipment connection within the connection/device and

circuit or at the panel. repair/replace.

Source:Ideal Industries, Inc.

Impedance Troubleshooting Tips

TABLE

4-3

Measuring Available Short-Circuit

Current

The SureTest can also measure (in kiloamps, kA)

the amount of available short-circuit current

(ASCC)—how much current can flow through

a circuit in spite of resistance factors such as wire

gauge and terminal connections. This will be