Technical Issues

  • My Luminaire doesn’t work, what should I do?

    If your lamps are failing to ignite in one of our double-ended luminaires, you should initially check that the lamps are properly installed—including using the right type of lamp, and right orientation (getter to ballast). Also ensure that the lamp holders are fully closed.

    For HID and LED luminaires, check the following:

    • Do you have power?
    • Is it the right voltage per the product label?
    • Is there power at the luminaire?
    • If controllable, is it commanded to be ON?
    • For HID luminaires, try swapping a troublesome lamp with a good one and see if you still experience problems.
    • Move your troublesome luminaire to a good location (verify power) and see if you are still having issues.

    If your luminaire still fails to function as it should, please send us a brief description of the problem(s) you are experiencing through the form on the contact us page, and a member of our technical support team will be in touch to address the issue.


  • How do I clean my fixtures luminaires? And how often should I be cleaning them?

    Regular cleaning and maintenance are essential for optimum performance of your luminaires, and we recommend that you check and clean your reflectors and luminaires every year, if possible. Cleaning your reflector and/or luminaire is easy and can be done using a simple 1:100 vinegar and water solution. Try to incorporate this as part of your regular routine when you are cleaning other parts of your greenhouse as well.

    Visit our Resources page for our maintenance recommendations and instructions on cleaning your reflectors and installing double-ended lamps.

    Watch our how-to video on cleaning your reflectors and luminaires.


  • Where can I find installation and maintenance instructions?

    A whole range of useful information is available in our Resources section—including installation instructions, helpful “how to” videos, maintenance guidelines and more.

  • Where can I go for light planning advice?

    Successful grow lighting starts with a carefully considered lighting plan. A lighting plan calculates the best possible coordination of luminaires, reflectors, patterns, distance between luminaires and crop, etc. Complete the relevant form for a custom, no obligation light plan for your project.

  • How do I safely dispose of my old lamps?

    Some lamps used in our luminaires contain a small amount of mercury or other materials that may be considered hazardous. The best way to prevent these materials from entering the waste stream and having a negative impact on our environment is to recycle them.

    In addition to our collective responsibility to protect the environment, there are federal mandates requiring that lamps are disposed of responsibly. The National Electrical Manufacturers Association (NEMA) has created an interactive map that outlines current mercury-containing product legislation by state.

    Contact a licenced lamp recycler near you in the USA or Canada to arrange for the safe and responsible disposal of your lamps.

  • How do I safely dispose of my legacy magnetic ballasts and/or capacitors?

    Older magnetic ballasts and/or capacitors, may contain Polychlorinated Biphenyl (PCB) based oils (used for cooling and insulation). The easiest way to tell whether your legacy lighting components contain PCBs, is to check the label part itself. If they do not contain PCBs, the label will likely include wording to the effect of “non-PCB” / “no PCB” / “PCB free”. Electronic ballasts DO NOT contain PCBs.

    Since PCBs are considered hazardous waste, any lighting components in which they are used, must—according to the Canadian Environmental Protection Act and the US Code of Federal Regulations (CFR)—be responsibly disposed of to avoid any environmental contamination.

    In many jurisdictions, a formal “certificate of recycling” (from a permitted hazardous waste recycling facility) is required to be submitted as part of a lighting retrofit rebate program.

    There will be a fee associated with the disposal of these PCB containing components, but the utility rebate customers receive for their lighting retrofits, is intended to compensate (at least partially) for the recycling costs that will be incurred in recycling these older lighting technology components.

    Contact a licenced recycler near you in the USA or Canada to arrange for the safe and responsible disposal of any PCB containing legacy components.

  • When should I replace my lamps?

    For high pressure sodium lamps, replacement is recommended after 10,000 hours of operation. Metal Halide lamps depreciate in output much quicker than HPS lamps and group re-lamping is recommended after 8,000 hours of operation (under normal operating conditions).   Some lamp failure can occur before these recommended intervals and single lamp replacement should be considered where necessary.

  • What Voltage should I use?

    We always recommend speaking with a licensed electrician before deciding what voltage to use to run your luminaires. The luminaire voltage will be noted on the product label.  A luminaire with a product label stating “120V-240V” will accept any one of these 3 voltages: 120,208 or 240 and will automatically sense the supplied voltage to ensure the same output to the light source regardless of the input voltage.  A luminaire with a product label stating “277V” will only accept a voltage of 277V.

    When it comes to lighting, we typically recommend going with the highest voltage available at your facility, which will also be the most efficient.  By using a higher voltage for your application, you can lower driver and conductor losses and increase efficiencies. But you should always consult with your electrician in advance to ensure you have an adequate power supply for your lighting and other equipment, including HVAC. They will need to consider your facility’s capacity, conductor sizes, circuit loads & voltage drop.

    For more information, please see our article Everything you need to know about voltage for your luminaire installation.

  • How long should I wait before re-striking my HPS luminaires?

    For maximum lifetime and performance of HPS luminaires (ballast and lamp), the luminaire should not be rapidly cycled on and off.  A 15-30 minute wait time should be observed when a luminaire is turned off before applying power again (re-strike) as this gives the lamp a suitable time to cool before the re-strike.

  • What is the maximum number of re-strikes / day for HPS luminaires?

    For maximum lifetime, the control system should be limited to 2 power-up (strikes) per day.  Excessive strikes per day may decrease the life of the ballast and/or the lamp.

  • What lamp do I use for a particular luminaire? (legacy products)

    Luminaires that have been in the field for 10+ years are likely to have had some parts replaced.  It is likely that the ballast, capacitor or ignitor has been replaced during regular maintenance.  This is not always done with the OEM parts, possibly making the product label information inaccurate.  When trying to find the correct lamp for your luminaire, it is important to know the current ballast and ballast ANSI code, if applicable.  Since horticultural lighting originated in Holland there are a variety of ballasts that were produced outside of ANSI standards.  This means the lamp you choose must match the ballast and the lamp base in your luminaire (e.g. E39 {Mogul} or E40).

    Since magnetic ballasts have slowly been phased out and replaced with electronic HID’s and LED’s, the lamp, ballast, ignitor and/or capacitor for older units may not be available anymore.  It is important that you are able to provide high-quality images of the luminaire, product label,  internal components of the luminaire (including the ballast label), lamp holder(s) and current lamps used, if requested by one of our customer service representatives.  The more images you are able to provide, the better when trying to determine what parts are needed for products.  To get in touch with our customer service team please use the contact page.


Product Information

Lighting for Plants

  • How much light do plants need?

    Each plant species (and sometimes even particular cultivars within the same species) has a particular DLI (daily light integral) requirement for optimal photosynthesis and plant growth. Plants are generally grouped into low, medium, high and very-high light species, so ensuring you are delivering the right light intensity is imperative for plant health, productivity and year-round consistency.

    Most plants need an average of 12-30 mols of light per day in order to produce a high-quality, high-yielding crop. For commercial growers, the use of supplemental lighting is essential, especially November through February when naturally occurring outdoor DLI values are typically between 5 to 15 mol/day.

    For more information on specific crop light needs please see our detailed crop cultivation guides.

  • What is the best type of lighting for my application?

    There are many different factors that should be considered when selecting the best type of lighting system (LED/HPS/MH/CMH/Hybrid) for any application. The decision  should always be based on a carefully considered light plan that is specific to that particular application. Most reputable lighting manufacturers offer light planning services. Growers, however, should be aware that a company who manufactures only LED or only traditional-source lighting products will, for obvious, reasons try to “sell” growers on the technology upon which their products are based. So working with a manufacturer who offers multiple product technologies will ensure an unbiased  recommendation so the  grower knows they are getting  the product/technology that’s the best fit for their particular application.

  • Should I make the switch to LED lighting?

    There are undoubtedly many benefits to growing with LEDs, including significant energy savings, spectral tunability, reduced heat, low maintenance and long lifetimes.

    However, converting to LED technology is a big investment, so growers should be sure to do their homework in advance.

    An incremental cost of four to five times that of HPS, means you have to look at many factors to determine if the ROI on converting to LED makes sense.

    Growers should consider not only the initial capital expenditure costs of the luminaires themselves, but also the incremental costs associated with a transition to LED lighting.  Growers in northern climates, for example, will have to compensate for the loss of heat from the traditional light sources in the winter—so the additional heating costs should be factored into the ROI calculation.

    A good way to get a true comparison between the cost of LED vs. traditional lighting is to look at the cost per µmol delivered, as the outputs can differ from one product to another.

  • What type of reflector should I be using?

    P.L. Light Systems offers a choice of multiple reflectors, each designed to deliver optimum performance for specific applications.

    The best reflector for your application will depend on several factors, including the mounting height above the canopy of the crop, the best distribution, type of crop, etc. Our sales and light planning teams will consider all these factors before making any recommendations. Please see our product page to view what reflectors we offer.

  • How do you measure light for plants?

    Plants use the electromagnetic spectrum for photosynthesis, referred to as Photosynthetically Active Radiation, or PAR, that encompasses the wavelengths from 400 nm (nanometers) to 700 nm. In addition to the spectral range of PAR, we also understand plants can detect wavelengths of light outside of this range including ultraviolet and infrared wavelengths.

    For plants, we use a term called Photosynthetic Photon Flux, PPF, which describes the quantity of PAR that is produced by a light source per second. This measurement is expressed in micromoles per second (µmol/s).

    A more important measurement used is Photosynthetic Photon Flux Density (PPFD), which describes the amount of light (intensity) used for photosynthesis (PAR) that arrives at the plant. PPFD it is given in units of micromoles of photons in the PAR range that is delivered to one square meter per second (µmol/m2/s).   This unit is important because you need to know how much light is being distributed at the crop level from the sun and/or luminaires to ensure plants are receiving the correct amount of light to hit your target DLI. PPFD should be measured at The crop canopy. Multiple readings should be taken, across the canopy, to ensure uniformity and accurate readings

    To determine how much light is needed over the course of a day for your crop, we also use a measurement called the Daily Light Integral (DLI), a parameter describing the cumulative PPFD over an entire day. DLI is strongly related to photosynthesis, growth rate, and overall plant productivity. The units for DLI are similar to that of PPFD but extend over an entire day (mol/m2/day). DLI will change over the course of the year, based on your geography. Most plants need a DLI of 12-30 mol/day.  More information can be found here referring to specific DLI maps for your region.  

    Note: When taking light measurements in a greenhouse, DO NOT use a Foot Candle/Lux sensor (which follows the sensitivity curve of the human eye and gives inaccurate information when comparing light sources with a different spectrum). Instead, use a quality quantum sensor (PAR-sensor) which is designed to follow the sensitivity curve of plants and measures the number of photons between 400 and 700 nm in µmol.