Categories: FURMAN

FURMAN PL-PRO C Classic Series 20 Amp Power Conditioner with Voltmeter Owner’s Manual

FURMAN PL-PRO C Classic Series 20 Amp Power Conditioner with Voltmeter



  • SMP (Series Multi-Stage Protection) with EVS (Extreme Voltage Shutdown)
  • LiFT (Linear Filtering Technology) with zero ground contamination
  • 20-segment LED tri-color AC voltage meter (allows easy verification of voltage range from a distance or in poor lighting)
  • Front panel mounted USB charger
  • Two Smooth Track retractable, long-life, low-heat, front panel LED lights with dimmer-power switch for rack illumination
  • The BNC connector on the rear panel accepts any standard (12VAC 0.5 amp) gooseneck lamp to illuminate the rear of your rack (Furman GN-I and GN-LED accessory gooseneck lamps are best for this application)
  • Eight rear panel AC outlets (three with wide spacing and hook and loop straps to accommodate and secure transformers – wall warts)
  • One front-panel convenience outlet
  • 20 amp (2400 watt) capacity
  • Five year limited warranty


Thank you for purchasing a Furman Classic Series power conditioner, and congratulations on your choice. Classic Series power conditioners feature Furman’s revolutionary Series Multi-Stage Protection (SMP) circuit, Extreme Voltage Shutdown (EVS), and our exclusive Linear Filtering Technology (LiFT). Together, these technologies comprise precisely what our customers have come to expect from Furman – uncompromised AC protection and purification. Our Classic Series has been precisely engineered to exceed the critical demands of audio/video professionals, contractors, broadcasters, and musicians alike.


Furman’s SMP surge suppression virtually eliminates service calls and costly “down time”. Traditional surge suppression circuits sacrifice themselves when exposed to multiple transient voltage spikes, requiring the dismantling of your system and repair of your surge suppressor. Not so with Furman’s SMP. Damaging transient voltages are safely absorbed, clamped, and dissipated. Your connected equipment is protected, while your Furman protects itself!
Unique to Furman’s SMP is its unparalleled clamping voltage, defined as the amount of voltage that is allowed to pass through to your equipment when the protection device is subjected to a transient surge or spike. While other designs offer clamping voltages that are well above 330 Vpk, Furman’s SMP clamps at 188 Vpk, (133 VAC RMS) even when tested with multiple 6000 Vpk – 3000 amp surges! This unprecedented level of protection is only available with Furman’s SMP technology.


Furman’s trusted over-voltage (EVS) circuitry protects against prolonged overvoltage conditions, such as accidental connections to 208 or 240 VAC, or an intermittent neutral. It does so by monitoring the incoming voltage and, when an unsafe condition is detected, triggering a relay which shuts off the incoming power until the overvoltage condition is corrected and the power switch is reset.


Unfortunately, traditional AC power conditioners have been designed for unrealistic laboratory conditions. Prior technologies, whether multiple-pole or conventional series-mode filters, could actually harm audio and video performance more than they help, due to the resonant peaking of their antiquated, non-linear designs. Under certain conditions, these designs can actually add more than 10 dB of noise to the incoming AC line! Worse still, lost digital data, the need to reboot digital presets, or destruction of sensitive digital converters are frequently caused by excessive voltage spikes and AC noise contaminating the equipment ground. Furman’s LiFT takes a different approach, ensuring optimal performance through linear AC noise filtering with no ground contamination.


The PL-PRO C features Smooth Track LED rack lights which produce virtually no heat and provide an extremely long lifespan. A dimmer control for the rack lights allows the user to adjust the level of illumination (by rotating clockwise/counterclockwise) or switch the lamps on and off (by pushing the knob in). A rear mounted BNC jack accepts any standard (12VAC 0.5 amp) gooseneck lamp for rear rack illumination.
The PL-PRO C is equipped with a front panel convenience AC outlet and eight rear panel outlets in two isolated banks. The outlets in Bank A are spaced to accommodate transformer plugs (wall warts) which may be secured with the included hook and loop straps. Since the banks are isolated from each other, it is recommended to connect analog equipment into Bank A and digital equipment into Bank B (or vice versa). The PL-PRO C’s 20 amp (2400 watt) capacity is supplied from a robust 12 AWG, 10 foot AC cord.
Additionally, the PL-PRO C offers a tri-color multi-segment LED AC voltage meter that displays incoming voltage in 2-volt steps. The voltmeter’s accuracy is ±2.0 volts. This informs the user whether the voltage is in or out of a safe range, even from a distance too great to accurately read the displayed voltage.


To obtain best results from your Furman Classic Series power conditioner, please read this manual carefully before using.


To reduce the risk of electrical shock, do not expose this equipment to rain or moisture. Dangerous high voltages are present inside the enclosure. Do not remove the cover. Refer servicing to qualified personnel only. The lightning flash with an arrowhead symbol is intended to alert the user to the presence of uninsulated dangerous voltage within the product’s enclosure that may be of sufficient magnitude to constitute a risk of electric shock.


(Please read prior to installation)

  1. Please read and observe all safety and operating instructions before installing your Furman Classic Series power conditioner. Retain these instructions for future reference.
  2. Your Classic Series conditioner should not be used near water – for example, near a bathtub, washbowl, kitchen sink, laundry tub, in a wet basement, or near a swimming pool.
  3. Do not place your Classic Series conditioner near high heat sources such as radiators, heat registers, stoves, or other appliances that produce extreme heat.
  4. The Furman PL-PRO C should only be connected to a 120 VAC, 50Hz/60Hz, 20 amp grounded electrical outlet. Do not defeat the ground or change polarization of the power plug.
  5. Route the AC power cord and other cables so that they are not likely to be walked on, tripped over, or stressed. Pay particular attention to the condition of the cords and cables at the plugs and at the point where they exit your Furman conditioner. To prevent risk of fire or injury, damaged cords and cables should be replaced immediately.
  6. Clean your Furman conditioner with a damp cloth only. Do not use solvents or abrasive cleaners. Never pour liquid on or into the unit.
  7. Your Furman conditioner should be serviced by qualified service personnel when:
    1. The power supply cord or the plug has been frayed, kinked, or cut.
    2. Objects have fallen or liquid has been spilled into the unit.
    3. The unit has been exposed to rain or extreme moisture.
    4. The unit does not appear to operate normally.
    5. The “Protection OK” indicator is not lit.
    6. The unit has been dropped, or the enclosure has been damaged.
    7. The retractable LED lights have failed.
  8. Your Furman conditioner requires that a safety ground be present for proper operation. Any attempt to operate the unit without a safety ground is considered improper operation and could invalidate the warranty.
  9. Do not attempt to service your Furman conditioner beyond what is described in this manual. All other servicing should be referred to qualified service personnel.



The Furman Classic Series power conditioners utilize a dimmer control for the two retractable Smooth Track light tubes. The dimmer knob controls the brightness of both front panel lamps. Turn it clockwise to increase brightness; turn it counterclockwise to decrease brightness.
The knob is also a momentary power switch for the lamps: push it in to turn the lamps on or off. When the lamps are not in use, we recommend turning the dimmer fully counterclockwise, or pushing the knob to the off setting to maximize the life of the LED’s. Whether the light tubes are fully extended or flush with the front panel, there will be no appreciable heat regardless of the dimmer setting due to the efficiency of our full light spectrum LED’s. All Furman Classic Series Conditioners feature a rear rack BNC socket which will accept any 12 VAC (0.5A) gooseneck lamp assembly (such as the Furman GN-LED or GN-I). Simply slide the BNC plug over the socket and rotate clockwise until the connector snaps into the locked position. The rear rack lamp can be powered on or off with the rear light switch which is adjacent to the BNC connector.


Furman’s Classic Series 20 amp capacity power switch is specifically designed to stand up to the enormous high in-rush current demands of many power amplifiers. Additionally, Furman magnetic circuit breakers are not sensitive to temperature, and will not raise the AC impedance as do many, less costly thermal breaker. If the 20 amp RMS current capacity of the PL-PRO C is exceeded, the spring tensioned-switch will immediately switch to the off position. You will need to switch the toggle back to the on position once the problem is corrected (typically by eliminating one component, or until the RMS current does not exceed 20 amps or 2400 watts).


The Extreme Voltage LED Indicator is normally off. It is located to the left of the power switch, though during normal use it will NOT be lit.
The Extreme Voltage indicator monitors a hazard common in the entertainment, remote broadcast, and AV contractor industries: wiring faults. For example: accidental connection to 208VAC where 120VAC is expected, or an open series neutral from a 208 to 240VAC electrical service. The Furman EVS circuit senses voltages that are so high that operation would be impossible and shuts the power down before damage can occur.
Upon initially applying power to the PL-PRO C, the Extreme Voltage indicator will illuminate to a bright red if the input voltage is above the extreme voltage cutoff. When this occurs, power will not be applied to the PL-PRO C’s outlets. If the unit has been operating with an acceptable input voltage and subsequently that voltage exceeds 140V, it will shut off power to the outlets and the Extreme Voltage LED will light.

NOTE: If the mains power is above the high cutoff voltage and has caused the EVS circuit to remove power from the PL-PRO C’s outlets, it cannot restore power without the operator manually turning the unit off, then on again. Avoid turning the unit back on without first checking the source of the problem and changing the AC source (if necessary).


Although the Furman SMP circuit assures virtually maintenance-free protection from transient voltage spikes and surges, nature has a way of occasionally creating electrical forces that are beyond the capabilities of ANY surge suppression device to absorb without some degree of damage (such as a direct lightning hit in an outdoor application). In the rare instance that this occurs, the green “Protection OK” LED indicator (located to the right of the retractable light tubes), will not be illuminated. If this happens, some level of protection from voltage surges will remain, but the PL-PRO C’s clamping voltage rating will be compromised and the unit must be returned to Furman for service.

NOTE: Furman’s Classic Series power conditioners do not compensate for high or low AC line voltage. If you frequently move your rack to different locations, derive power from generators, use very long extension cords, travel internationally, or are in an area prone to brownouts, you may benefit from the use of one of Furman’s AC Voltage Regulators.


This three-color, 20-LED bar-graph is an accurate, self-checking AC voltmeter that continually measures input AC voltage. The meter reads from 90 to 128 volts in 2 volt increments. The optimal range voltages are indicated in green, with moderate and extremely high or low voltages in yellow and red, respectively.
The voltmeter provides three special flashing patterns to indicate abnormal conditions:

  1. If only the single left-most (beneath the 90V mark) LED flashes, the input voltage is marginally low.
  2. If all of the LED’s on the voltmeter flash, the input voltage is marginally high. Power to the PL-PRO C’s outlets will remain unless the incoming voltage rises above the Extreme Voltage Shutdown (EVS) cutoff voltage (140 volts).
  3. (If none of the LED’s on the voltmeter are lit, and the Extreme Voltages LED indicator is illuminated, then the PL-PRO C has shut down power to its outlets because the input voltage is in a range considered extreme (in excess of 140 volts).


The Furman PL-PRO C’s USB charger provides an easy way to recharge many popular electronic accessories as well as cellular communication devices by simply plugging the re-charge cord into the front panel socket. Please note that as there are currently many standards for USB, some devices may not be compatible with our charger.


Your 20 amp Furman Classic Pro Series conditioner features rear panel AC outlets that are widely spaced for plug transformers (wall warts). Additionally, these may be secured for transport with hook and loop straps (included). Each outlet has threaded screw holes on either side to accommodate the hook and loop straps.


  • Symptom:
    • No power to the AC outlets.
      • Possible Cause:
        • The circuit breaker (located on the front panel) has tripped due to excessive load.
      • Action Needed:
        • Unplug one piece of equipment from the Furman conditioner and manually turn the unit off, then on again.
  • Symptom:
    • No power to the AC outlets, “Protection OK” indicator is not lit.
      • Possible Cause:
        • Either the AC outlet to which your Furman conditioner is connected has no AC voltage present, or the protection
          circuitry in your unit has been compromised.
      • Action Needed:
        • Plug the Furman conditioner into an AC receptacle where a nominal 120 VAC is present. If the problem persists,
          contact Furman for service.
  • Symptom:
    • Extreme Voltage (EVS) indicator lit.
      • Possible Cause:
        • Input voltage is above 140V causing power to the unit’s outlets to be shut down. Additionally, if the voltage is
          below 85V – 90V at turn on, the unit will not allow AC voltage to reach the outlets.
      • Action Needed:
        • Correct the line voltage, then turn the Furman conditioner on. If the voltage present is below 114 VAC or above 126 VAC, consider installing a Furman voltage regulator.


If you require technical support or equipment service, please contact the Furman Service Department at (760) 438-7000. You may also email
All equipment being returned for repair must have a Return Authorization (RA) number. To get an RA number, please call the Furman Customer Service Department. Before returning any equipment for repair, please be sure that it is adequately packed and cushioned against damage in shipment, and that it is insured. We suggest that you save the original packaging and use it to ship the product for servicing. Also, please provide a note giving your name, address, phone number, RA number and a description of the problem.


SAVE YOUR SALES RECEIPT! The receipt is your proof of purchase and confirms the product was purchased at an authorized Furman dealer. It will need to be submitted to Furman in order to process any warranty claims.

Furman, a brand of Nortek Security and Control LLC, warrants its PL-PRO C (the “Product”) as follows:
Furman warrants to the original purchaser of the product that the product sold hereunder will be free from defects in material and workmanship for a period of five years from the date of purchase. If the product does not conform to this Limited Warranty during the warranty period (as herein above specified), purchaser shall notify Furman of the claimed defects by calling (760) 438-7000 or via email ( If the defects are of such type and nature as to be covered by this warranty, Furman shall authorize purchaser to return the product to Furman headquarters. Warranty claims MUST be accompanied by a copy of the original purchase invoice or receipt showing the purchase date. Shipping charges to Furman headquarters must be prepaid by the purchaser of the product. Furman shall, at its own expense, furnish a replacement product or, at Furman’s option, repair the defec-tive product. Return shipping charges back to purchaser will be paid by Furman.


Furman does not warrant against damages or defects arising out of improper use or abnormal handling of the product, or against defects or damages arising from improper installation. This warranty shall be cancelable by Furman at its sole discretion if the product is modified in any way without written authorization from Furman or Nortek Security and Control LLC. This warranty also does not apply to products upon which repairs have been affected or attempted by persons other than pursuant to written authorization by Furman or Nortek Security and Control LLC.

THIS WARRANTY IS EXCLUSIVE. The sole and exclusive obligation of Furman shall be to repair or replace the defective product in the manner and for the period provided above. Furman shall not have any other obligation with respect to the products or any part thereof, whether based on contract, tort, strict liability or otherwise. Under no circumstances, whether based on this Limited Warranty or otherwise, shall Furman be liable for incidental, special, or consequential damages. This Limited Warranty states the entire obligation of Furman with respect to the product. If any part of this Limited Warranty is determined to be void or illegal, the remainder shall remain in full force and effect.


    • 20 amps
    • 90 to 139 VAC
    • 140 VAC typically
    • Line to neutral, zero ground leakage
    • 188 VAC peak @ 3,000 Amps, 133 VAC RMS
    • 1 nanosecond
    • 6,500 amps
    • 10 dB @ 10 kHz, 40 dB @ 100 kHz, 50 dB @ 500 kHz
      Linear attenuation curve from 0.05 – 100 Ohms line impedance
    • 1.75” H x 19” W x 10.5” D.
    • 12 lbs. (5.5 kg.)
    • Steel chassis, .120” brushed and black anodized aluminum front panel; glass epoxy printed circuit boards
    • 15 VA

Nortek Security & Control
5919 Sea Otter Place, Carlsbad, CA, 92010
USA ©2021 Nortek Security & Control LLC. All rights reserved.
Furman is a registered trademark of Nortek Security & Control LLC.
10032266 Rev-A


Documents / Resources

FURMAN PL-PRO C Classic Series 20 Amp Power Conditioner with Voltmeter [pdf] Owner's Manual
PL-PRO C Classic Series 20 Amp Power Conditioner with Voltmeter, PL-PRO C, Classic Series 20 Amp Power Conditioner with Voltmeter, 20 Amp Power Conditioner, Power Conditioner


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