Power meters for 3D printers: voltage, energy and relay choices

Why a consumption overview is not a measurement

The power consumption guide covers the general topic; a meter documents your actual setup. HT90's page provides a useful example: Prusa says consumption depends on material and publishes peak power, without a per-print energy value. This concerns that particular page, not every manufacturer publication. For your purchase, obtain both the printer's input specifications and the types of data the meter provides.

A compatible meter that records energy can provide a reading for a print, but the sources on this page do not compare measurement accuracy or how the listed models behave. Prusa says HT90 consumption depends on material and publishes peak power, not kWh per job. For a cost estimate, use a reading from the exact setup and record its conditions; no measurement was performed for this page.

Record at least voltage, current, connection type, load conditions and operating temperature from the exact meter manual. Then assess measurement and control separately: remote switching is not energy measurement. For a wired module such as POWR3, include its required installation service in the budget rather than comparing only its hardware price with a plug-in unit.

Read the rated load before the feature list

Sonoff's index identifies families and links to manuals. This review also uses V1.0 PDFs for POWR3 and S61SZBTPB, whose conditions are detailed below. Do not transfer their ratings to POW Elite, S40, S60, SPM or POWCT: a name in the index does not verify another variant, its connection requirements or compatibility with your printer.

HT90 is a specific example: Prusa publishes a 1900 W peak for its 230 V version and 1800 W for its 110 V version, and says the chosen version supports one voltage without switching. These figures are not a per-print measurement and do not compare the HT90 with an open desktop printer or establish a meter rating for another machine.

Do not turn a power-supply rating into the printer’s mains-input peak: the sources reviewed here do not establish that relationship. If the printer maker does not publish its input rating or peak, these sources leave capacity compatibility undetermined. Check the printer maker and exact meter manual before choosing; an estimate alone does not validate a model.

Two exact manuals: POWR3 module and S61SZBTPB plug

POWR3's V1.0 manual describes a Wi-Fi smart switch with power monitoring, remote control, scheduling and sharing. It specifies input and output of 100–240 V AC at 50/60 Hz, maximum load of 25 A/5500 W, 2.4 GHz Wi-Fi and an operating temperature of −10 to 40 °C. These are published limits for this module, not permission to draw 5500 W at every voltage. The manual's conditions and the installation's requirements must both be satisfied.

POWR3 requires wiring: its manual calls for installation and maintenance by a professional electrician, with power off before work on connections. This page supplies no wiring procedure. To compare a workshop solution, provide the professional with the full module reference, intended printer and its input manual. V1.0 is the document examined here; confirm that it matches the actual version being offered before buying.

S61SZBTPB V1.0 is a Zigbee Type B plug for 100–125 V, 50/60 Hz systems, with published maxima of 15 A and 1875 W. Its manual specifies indoor use, −10 to 40 °C operation and an upstream 15 A MCB or RCBO. It describes a relay, remote control and energy monitoring. This is neither a European variant nor a meter without switching. Documented pairing uses a Zigbee gateway; do not assume a direct Wi-Fi link because other products from the brand use one.

Voltage, printer version, and outlet type

A plug that looks similar to another does not inherit its electrical limits. S61SZBTPB is explicit: Type B and 100–125 V. Changing plug shape with an adapter does not turn it into a 230 V model. For your country, obtain the manual for the variant actually sold and compare it with your printer input. That manual's protection requirements belong to that specific reference.

HT90 documentation says each chosen machine supports one mains voltage—230 V or 110 V depending on version—with different peak figures. This applies to HT90 and is not a sizing rule for all printers. For another machine, consult its electrical input data and the proposed meter’s manual.

Also separate instantaneous power, expressed in W, from accumulated energy, expressed in Wh or kWh. A peak describes an instant; it does not establish a job's energy alone. Before choosing, check that the interface lets you record the quantity you need, its unit and retention or export conditions. The examined manuals provide no metrological comparison between meters here or accuracy tested on a printer.

Record a session without treating it as a comparative test

To prepare an energy log, our editorial suggestion is to record printer and voltage variant, meter and version, material, file, profile and reading boundaries. State whether preparation, printing, cooling or idle time is included. This framework makes your notes understandable; it is not a validated laboratory protocol or a procedure published by Prusa or Sonoff. Keep connection and reading operations within the equipment manuals.

If a meter provides a cumulative energy register, subtracting the starting reading from the ending reading describes the chosen interval, provided units stay consistent and register behavior is accounted for under its manual. Record both values and times rather than copying only an instantaneous-power screen. Log a restart, reset or another device included in the measured scope before attributing that difference to one print.

For the cost calculator, enter energy in kWh with the tariff applicable to your case and keep the reading conditions. Do not assign one session's result to all future parts. To compare two profiles, record what changed and what stayed the same; these sources supply no guaranteed uncertainty margin or repeatability. No actual meter reading was taken for this page.

Relays and recovery: separate measurement from control

HT90’s page says it has no power recovery feature and that chamber cooling can cause a print failure for most materials used with this machine. This limitation concerns HT90 and does not describe all printers or meters.

POWR3 and S61SZBTPB document load control, so examine scheduling and power-on-state settings provided by their manuals before connecting a print. Sonoff's index also names MINI-1GP as Non-Switch. That label distinguishes a function without switching, but does not document all its installation limits here or guarantee continuous mains supply. HT90's page discusses an external third-party UPS without validating a model on this page.

The supplied sources do not show that a plug-in meter is an electrical protection device. Check the model limits and maker instructions in the exact manual; index titles alone do not select equipment or confirm an installation is safe.

Sources and limits

• SONOFF — User Manual index, model families
• Prusa Knowledge Base — HT90 Power Consumption
• SONOFF — POWR3 User Manual V1.0
• SONOFF — S61SZBTPB User Manual V1.0 (Type B)

We organize manufacturer and community documentation; we have not measured these products ourselves. The manual for your exact model takes precedence over general guidance.