Short answer: Both articles deal with equipment that sits next to motors. A phase converter (Article 455) lets certain three-phase loads run from a single-phase supply. A rotary converter produces a third, “manufactured” phase while it runs; a common static converter mainly helps the motor start. A power factor correction capacitor (Article 460) supplies part of a motor’s magnetizing current, so the line current drops. That drop matters for the exam: when a capacitor is connected on the load side of the motor overload, the overload is selected from the reduced current, not the motor’s full nameplate current (NEC 430.32(A)(1) Informational Note). Capacitors also store a charge after the power is off, and Article 460 has rules for draining it.
PSI lists Motors and Generators as a subject area on the Texas Journeyman exam: 5 scored NEC Knowledge questions and 2 scored Calculations questions. PSI does not say how many cover these articles or which subject area it files them under. The Texas Journeyman Practice Pack has 1,000 original questions and 10 timed mock exams in the real two-part format, with step-by-step solutions for every calculation. Try free practice questions without signing up. Get the full pack for US$39 with one payment.
Tsai Electro is an independent learning site. Not affiliated with TDLR, PSI or NFPA. We explain the ideas in our own words and do not reproduce NEC text. Check every rule and table value in your own 2026 NEC, and follow your supervisor and the local inspector.
Phase converters: what the question is describing
A shop has only single-phase service but owns a three-phase lathe. A phase converter takes the two single-phase lines and adds a third line that it produces itself. That third line is the manufactured phase.
| Type | How it works |
|---|---|
| Rotary | An idler motor spins and generates the third phase; it can run several machines |
| Static | Capacitors create a phase shift to start the motor; after starting, the motor runs on single-phase power at reduced available horsepower |
Points to look up in Article 455 of your 2026 NEC before exam day: how the converter’s supply conductors are sized, where the disconnecting means goes, and how the manufactured phase is marked so it is not used to feed single-phase loads. Because the manufactured phase is not as stiff as a utility phase, it is kept off single-phase loads.
Capacitors: why the current goes down
An induction motor draws two kinds of current: the part that does work and the magnetizing part that builds the field. A capacitor placed near the motor supplies much of the magnetizing part locally. The supply only has to deliver what is left, so the line current falls and the power factor rises toward 1.
Power factor in one line. Power factor = real power (kW) ÷ apparent power (kVA).
Worked example: power factor and line current
A motor load draws 40 kW at a power factor of 0.80.
- Apparent power before. 40 ÷ 0.80 = 50 kVA.
- Correct to 0.95. 40 ÷ 0.95 = about 42.1 kVA.
- What it means. The work done (40 kW) did not change, but the supply now delivers about 42.1 kVA instead of 50 kVA, so with the same voltage and phase arrangement, the current on the supply conductors drops by the same proportion, about 16 percent.
The overload trap
Because the capacitor lowers the current the overload sees, the overload is selected from that reduced current when the capacitor is connected on the load side of the motor overload device (NEC 430.32(A)(1) Informational Note). The Informational Note points to Article 460 for the rule. If you set the overload from the full nameplate current, it can trip too late to protect the motor. For the motor overload math itself, see NEC 430 motor circuits and calculations.
Stored charge: treat every capacitor as live
A capacitor can hold a dangerous charge after the circuit is opened. Article 460 has rules on draining that charge and on the time it takes; check the exact values in your 2026 NEC. On the job, follow your employer’s lockout/tagout and capacitor discharge procedures, and verify the stored energy is gone before work starts. Opening the disconnect alone does not make a capacitor safe to touch.
Check yourself
- A load draws 30 kW at a power factor of 0.75. What is the apparent power? 30 ÷ 0.75 = 40 kVA.
- A capacitor is installed on the load side of a motor overload. Is the overload set from the full nameplate current? No. It is selected from the reduced current.
- What is the third line produced by a phase converter called? The manufactured phase.
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Find 455 and 460 faster on exam day
NFPA 70, National Electrical Code, 2026 Edition (softcover). In your notes next to 430.32(A)(1), write “capacitor on load side of overload: see 460.11,” so the overload trap sends you to the right rule. The Texas exam is open book. PSI allows a soft-bound NEC with highlighting, underlining and notes made in advance. Loose-leaf, spiral-bound and ring-bound copies are not allowed, and only permanent index tabs made or supplied by the NEC publisher are permitted; homemade and third-party tabs are not.
FAQ
What is a phase converter?
Equipment that lets certain three-phase loads run from a single-phase supply. A rotary converter produces a third, manufactured phase; a static converter mainly helps the motor start.
Why do power factor capacitors lower the current?
They supply part of the motor’s magnetizing current locally, so the supply delivers less current for the same real power.
How does a capacitor change the motor overload setting?
When the capacitor is on the load side of the overload, the overload is selected from the reduced current, not the full nameplate current.
Are capacitors dangerous after the power is off?
They can hold a charge. Article 460 has rules for draining it; follow lockout/tagout and discharge procedures and verify the stored energy is gone before touching it.
Are motors on the Texas Journeyman exam?
PSI lists Motors and Generators as a subject area, with 5 scored NEC Knowledge questions and 2 scored Calculations questions.
Sources checked October 2026
- PSI Candidate Information Bulletin, Texas electrician examinations (updated September 15, 2026): https://test-takers.psiexams.com/api/content/bulletin/1682
- NFPA 70, National Electrical Code, 2026 Edition, 430.32 and Articles 455 and 460
