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Fluke 393 FC Review: Is This 1500V Solar Clamp Meter Worth the Professional Price?

The Fluke 393 FC is the clamp meter Fluke designed for utility-scale and commercial solar: a 1500 V DC category rating, weather resistance, DC power and polarity functions, and a thin jaw for combiner boxes. This review explains why those features exist and who needs them.

By the Akermin Editorial Team · 4 min read

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Fluke 393 FC Review: Is This 1500V Solar Clamp Meter Worth the Professional Price?

Fluke · Fluke 393 FC Solar Clamp Meter, CAT III 1500 V, IP54-Rated, DC Power Measurements, Audio Polarity Indicator, Visual Continuity, Fluke Connect Software Enabled, Thin Jaw For Easy Access, Includes iFlex

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Price and availability are shown on Amazon and can change at any time.

Verdict

The Fluke 393 FC is not a general-purpose clamp with a solar sticker; it is a clamp designed around the specific hazards and measurements of photovoltaic DC. The CAT III 1500 V DC rating covers the string voltages of commercial and utility systems. The IP54 rating means it tolerates dust and rain on a roof or in a field. DC power measurement, an audible polarity indicator and visual continuity address the three checks a PV technician repeats all day. The thin jaw fits between the closely spaced cables in a combiner box, and the included iFlex probe reaches the ones it cannot. Fluke Connect logs readings to a phone. For residential installers working at 600 V, it is more meter than needed; for anyone commissioning or maintaining large PV, the documentation supports it as the purpose-built option.

Who It Is For

  • Commissioning and O&M technicians on commercial and utility-scale PV.
  • Electrical contractors who install 1500 V string systems.
  • Test engineers who need documented DC power readings for performance ratio checks.

Our guide to choosing a clamp meter for solar PV explains where 600 V, 1000 V and 1500 V ratings each fit.

Documented Specifications

Item Documentation
Safety rating CAT III 1500 V
Ingress protection IP54, rated for outdoor use
Measurement type True RMS
PV functions DC power measurement, audio polarity indicator, visual continuity
Jaw Thin jaw for access in crowded combiner boxes
Flexible probe iFlex included
Connectivity Fluke Connect software enabled

The manufacturer’s datasheet gives the current and voltage ranges and their accuracy. We have not reproduced range figures here; consult the datasheet for the current revision.

What the 1500 V Rating Means

Safety categories describe the transient overvoltage a meter must survive, not merely the steady voltage it can display. A CAT III 1000 V meter is designed for transients on 1000 V distribution circuits; a 1500 V PV string exceeds that steady-state limit, so a 1000 V meter is outside its design envelope before any transient is considered. The 393 FC is built and tested for CAT III at 1500 V DC. Combined with IP54, it is intended to be used on the roof, at the combiner and at the inverter DC input in the conditions those locations present. For 600 V residential strings a standard AC/DC clamp is adequate, and the 393 FC’s advantages are convenience rather than necessity. Background is in choosing a solar PV tester.

DC Power, Polarity and Continuity

String commissioning involves three repeated checks: open-circuit voltage, operating current and the power those produce, plus polarity before connection and continuity of grounding conductors. The 393 FC computes DC power from voltage and current so a technician can compare a string’s output with the expected value from irradiance and module ratings. The audio polarity indicator gives a tone for polarity so the technician can keep watching the probe tips on a live string. Visual continuity gives a clear indication for bonding checks in bright sunlight where a beep is hard to hear. For the underlying procedures see measuring open-circuit voltage and measuring solar panel current.

Thin Jaw, iFlex and Fluke Connect

Combiner boxes pack string cables closely, and a conventional clamp jaw often cannot get around one conductor without including its neighbour. The thin jaw is the fix. The included iFlex flexible probe handles the opposite problem: large inverter output conductors and busbars that no rigid jaw fits. Fluke Connect sends readings to the phone app over Bluetooth, which lets one technician read a meter clamped inside a live enclosure from outside the arc-flash boundary and record every string in a report rather than on a clipboard.

Strengths

  • Rated for 1500 V DC PV systems, with IP54 weather resistance.
  • Purpose-built DC power, polarity and continuity functions.
  • Thin jaw and included iFlex cover combiner boxes and large conductors.
  • Fluke Connect logging for commissioning records.

Limitations

  • More capability and cost than a residential installer working at 600 V needs.
  • Bluetooth logging depends on the Fluke Connect app and account.
  • The thin jaw has a smaller opening than the general-purpose 37x series.

How It Compares

The Fluke 377 FC and 374 FC are the general-purpose Fluke Connect clamps at 1000 V and suit residential and commercial electrical work including 1000 V PV. For irradiance and module temperature during a commissioning test, the Seaward Solar Survey 200R is the companion instrument. The Seaward PV:1525 is a dedicated 1500 V string tester that adds insulation resistance measurement.

How We Research

This review is based on the manufacturer’s published specifications, the Amazon product listing and owner reports. We did not run laboratory tests. See also building a basic solar testing toolkit.

Fluke 377FC AC/DC TRMS Non-Contact Voltage Wireless Clamp w/iFlex

Fluke 377FC AC/DC TRMS Non-Contact Voltage Wireless Clamp w/iFlex

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FLUKE-374 FC 600A Ac/Dc TRMS Wireless Clamp

FLUKE-374 FC 600A Ac/Dc TRMS Wireless Clamp

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Seaward Solar Survey 100 - Irradiance Meter

Seaward Solar Survey 100 - Irradiance Meter

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Products shown because their documented specifications fit this guide. Price and availability are on Amazon and can change.

Frequently Asked Questions

Why does a solar clamp need a 1500 V rating?

Modern commercial and utility PV strings operate up to 1500 V DC. A clamp rated to 1000 V is not designed for the transients in those systems. The 393 FC is rated CAT III 1500 V DC, which is the category and voltage those installations require.

What is the audio polarity indicator for?

When probing DC strings you need to know which conductor is positive without looking at the display. The 393 FC gives an audible indication of polarity so you can keep your eyes on the probes.

Does it measure DC power?

Yes. It measures DC voltage and DC current and calculates DC power, which is what commissioning and performance checks on a string need.

Is the iFlex included?

The listing states that the iFlex flexible current probe is included. It wraps around large or awkwardly placed conductors that the jaw cannot reach.

Affiliate disclosure: Akermin earns a commission from qualifying Amazon purchases made through links on this page. Our editorial picks are based on documented specifications and owner feedback, not commissions.