You're Guiding an Apprentice by Phone Through a Diagnosis: Decision Tree

Why this matters

The call comes in while you are elbow-deep in another job: the apprentice you sent solo is stuck, and the customer is waiting. You can diagnose through the phone, but a live guided session has its own failure modes: a rushed setup, a misheard number, a green hand nudged past what is safe. This tree is the order to run a phone-guided diagnosis so you get a real answer, not a confident guess.

Start here: safety before the first question

Before any diagnosis, settle the hazard.

• If the apprentice describes a gas smell, smoke, a burning odor, arcing, or water at live electrical: the check stops. Have them stop, get themselves and the customer clear, and secure or shut off from a safe position. Diagnose nothing until the hazard is handled.
• If the next step involves stored energy, live conductors, gas, or pressure they are not trained for: do not talk them into it. That is a drive-out or a hold, not a coach-through.

Only once the situation is safe do you move to the diagnosis.

Step one: find out what you are working with

Ask two things before you branch:

• What can they safely do? Confirm their comfort with the meter, the panel, the tool the check needs. Believe a hesitation; a green hand who says "I think so" cannot.
• What is the unit doing right now? Get the present symptom in their words, then translate it into an observable you can test.

Branch on the first observable

Pick the single cheapest, safest check that splits the problem in half, and have them run it while you stay on the line.

If they report a clear, in-range reading: good, but accept it only after confirming the setup (range, leads, the two points). Move to the next branch. A clean reading with a wrong setup is worse than no reading.

If they report a reading that cannot be right: stop and treat it as a setup or method error first, not a real finding. Walk the meter setup before you believe the number.

If they cannot get the reading at all: do not escalate the electrical difficulty. Step back to a simpler observable - a visual, a listen, a touch-test on a de-energized part - that gets you partway.

If they go quiet or unsure: that is a signal, not a gap to talk over. Ask them to describe what they see, plainly. Confusion on the line usually means the task has passed their depth.

Keep the session honest

• One instruction at a time. Stack three steps and a green hand does the first and guesses the rest.
• Make them read raw, not conclude. "Tell me the number," never "is it good?"
• Photo the decisive reading. A picture of the meter face and probe placement settles any doubt on the call the whole diagnosis rests on.

When to stop guiding and change plans

Pull the plug on the phone session when:

• The next real step is unsafe for their training level.
• You have walked the setup twice and still cannot trust the reading.
• The fault will not reproduce for them.

Then it is drive-out, reschedule, or send another hand, not one more question.

Recap

1. Handle any hazard first; stop the check if the next step is beyond their training.
2. Establish what they can safely do and the present symptom.
3. Run the cheapest splitting check live; confirm setup before believing any reading.
4. Simplify when they cannot get it; treat impossible readings as setup errors.
5. Stop guiding when it turns unsafe, untrustworthy, or unreproducible.

References

• Trade-standard practice for supervised remote diagnosis
• OSHA guidance on qualified persons for electrical and hazardous work
• See related: The Apprentice Reports a Reading That Can't Be Right; Talk the Apprentice Through It or Drive Out Yourself