416

What voltage should a meter indicate when placing the leads on the line side and load side of the B fuse inside a 600-volt disconnect? The disconnect is on and the system voltage is 480/277.

0

What voltage should a meter indicate when placing the leads on the neutral and the ground of a 208/120, 3 phase, 4 wire system?

0

A 15-amp, single phase circuit runs from the panel to a bedroom and only energizes all the receptacles and the incandescent light in that bedroom. Assuming everything is wired and working correctly, what voltage reading would be plausible when you measure the line side of switch to load side of switch? (switch is on)

0 volts

A 15-amp, single phase circuit runs from the panel to a bedroom and only energizes all the receptacles and the light in that bedroom. Assuming everything is wired and working correctly, what voltage reading would be plausible when measuring the receptacle neutral conductor to ground?

0 volts

A 15-amp, single phase circuit runs from the panel to a bedroom and only energizes all the receptacles and the incandescent light in that bedroom. Assuming everything is wired and working correctly, what voltage reading is plausible when you measure the line side of switch to load side of switch? (switch is off)

120 volts

A 15-amp, single phase circuit runs from the panel to a bedroom and only energizes all the receptacles and the light in that bedroom. Assuming everything is working correctly, what voltage reading would be plausible when measuring the receptacle phase conductor to ground?

120 volts

What voltage should a meter indicate when placing the leads on phase A and phase B of a 208/120, 3 phase, 4 wire system?

208

What voltage should a meter indicate when placing the leads on phase A and ground of a 480/277, 3 phase, 4 wire system?

277

What voltage should a meter indicate when placing the leads on phase A and the neutral of a 480/277, 3 phase, 4 wire system?

277

A light over top of a set of stairs works some of the time but not always. What could be a possible reason for this fault?

3-way switch is miswired

What voltage should a meter indicate when placing the leads on phase A and phase C of a 240 volt delta system?

480

What voltage should a meter indicate when placing the leads on the line side of phase B fuse and the load side of the C fuse inside a 600 volt disconnect? The disconnect is on and the voltage is 480/277.

480

:Load side of breaker to neut - 120 Load side of breaker to ground - 120 Line side of switch to neut (switch in on pos) - 120 Line side of switch to ground (switch in on pos) - 120 Line side of switch to neut (switch in off pos) - 120 Line side of switch to ground (switch in off pos) - 120 Load side of switch to neutral (switch in on pos) - 120 Load side of switch to ground (switch in on pos) - 120 Load side of switch to neut (switch in off pos) - 0 Load side of switch to ground (switch in off pos) - 0 Phase fixture wire on light fixture to neut (switch in on pos) - 120 Phase fixture wire on light fixture to ground (switch in on position) - 120 Tab in bottom of socket to threaded part of socket (switch in on pos) - 0 Tab in bottom of socket to threaded part of socket (switch in off pos) - 0 Cont between neutral and ground at panel - .2 Cont between neut and G at switch - .2 Cont between neut and G at light box - .2

Bad light fixture

At which stage of troubleshooting should tools be first used?

Be systematic

A dedicated circuit feeds a light in a dwelling. The light is on all of the time. What could be a possible reason for this fault?

Defective switch

What helps when troubleshooting circuits?

Experience Knowing electrical codes Being logical

A 240-volt, single phase fused disconnect that feeds a motor is being tested. Meter leads are placed on the line side and load side of both fuses. The switch is on. The following readings are observed:Line side of Fuse A to line side of Fuse B - 240 voltsLine side of Fuse A to load side of Fuse B - 240 voltsLine side of Fuse B to load side of Fuse A - 0 voltsLoad side of Fuse A to ground - 120 voltsLoad side of Fuse B to ground - 120 voltsWith 100% certainty, what is the state of both fuses?

Fuse A is bad, Fuse B is good

What is the first step in the troubleshooting process?

Gather information

It has been determined that three bedrooms in a dwelling are on the same circuit. Bedroom one is closest to the panel, then bedroom 2, then bedroom 3. The overhead light and receptacles all work in bedroom 1. The overhead light does not work, but all the receptacles work in bedroom 2. Nothing works in bedroom 3. What's the most plausible reason for this fault?

Neutral came apart in bedroom 2 switchbox

A dedicated circuit feeds a light in a dwelling. The light never works. What could be a possible reason for this fault?

Neutral connection came apart Defective switch Bad breaker Bad lamp

The secondary side of a 480/277 volt to 208/120 volt transformer feeds a panelboard. The following readings are observed at the panelboard:Phase A to ground - 78 voltsPhase B to ground - 104 voltsPhase C to ground - 97 voltsPhase A to neutral - 122 voltsPhase B to neutral - 119 voltsPhase C to neutral - 123 voltsPhase A to B - 210 voltsPhase B to C - 214 voltsPhase A to C - 209 voltsNeutral to Ground - 54 voltsIs the transformer operating normally? If not, what is a possible reason why?

Neutral wasn't bonded in the transformer

A 240-volt, single phase fused disconnect that feeds a motor is being tested. Meter leads are placed on the line side and load side of both fuses. The switch is on. The following readings are observed:Load side of Fuse A to ground - 0 voltsLoad side of Fuse B to ground - 0 voltsLoad side of Fuse A to load side of Fuse B - 0 voltsWith 100% certainty, what is the state of both fuses?

Not enough information

Why is it important to understand the malfunction when troubleshooting?

The system could be working perfectly fine To help narrow possible causes of the problem To save time during the troubleshooting process

Once a voltage is found that is not expected, ___.

continue to check all possible voltages because there could be other underlying issues

A motor is controlled by a start/stop station. The operator pushes the start button, and nothing at all happens. If the motor starter contacts are manually closed, the motor runs. This is more likely a ___ problem.

control

A motor is controlled by a start/stop station. The operator pushes the start button. The motor starter makes odd noises and heats up. This is more likely a ___ problem.

control

When troubleshooting, ___.

multiple components may need to be fixed/replaced

A motor is controlled by a start/stop station. The operator pushes the start button. The motor runs slowly and then trips the overloads. This is more likely a ___ problem.

power

A motor is controlled by a start/stop station. The operator pushes the start button. The motor starter activates, but the motor does not run. This is more likely a ___ problem.

power

A fused combination motor starter controls a 3-phase motor. Line side voltage is 480 volt. There is a control transformer to reduce the voltage to 120 for the controls. The starter is controlled by a start/stop station. The start button is pushed, and the motor runs slow and then trips the C overload. What would be a possible reason for this fault?

Phase B fuse is bad