Frequently asked questions

  • What does an LED driver do?

    A driver is used to output the necessary constant current or voltage required for our LED product operation. Our constant current drivers operate at 350mA or 700mA depending on the product and require the luminaries to be wired in series. Our constant voltage drivers operate at 24V CV and this is used to operate our Contour LED strip light.

    Unlike traditional transformers used with halogen or LED retrofit lamps which convert mains 230V down to 12V, LED drivers allow for multiple dimming platforms such as Phase, 0-10V and DALI dimming which provide a smoother dimming performance with the addition of a ‘DRINT’.

    What is a DRINT?
    A DRINT is used in conjunction with a Constant Voltage Driver to enable smooth dimming via a 1-10V or Dali control.


  • Can I return my products if they are no longer required – Returned Material Authorisation (RMA)?

    It is possible to return products, but this will need to be arranged prior with your current sales person before any goods are shipped back to us.

    The sales person will issue you with a Returned Material Authorisation (RMA) form along with an RMA number to fill out and return via email.

    Once you have received the RMA number and have agreed on the terms with your John Cullen representative, the goods can now be sent back with the completed form attached to the sales person’s attention.

    This will enable us to track the status of the RMA all times.

  • Who can I contact if we have any installation queries?

    Our sales team are able to help with most queries however our technical team are on hand also to further assist.

    Please contact our customer service centre on 020 7371 9000 for any queries that you may have.

  • Do you carry out contractor training?

    Yes, we run a John Cullen Lighting approved contractor scheme in which contractors attend our customer service centre in Bagley’s Lane London to carry out product training and installation guidelines along with Q&A sessions.

    Successful contractors are then added to our list of approved contractors that we recommend to clients.

    For more information contact our customer service centre on 020 7371 9000.

  • Do you carry out site visits?

    Yes, we can provide a site attendance form to clients which requires filling out before attendance.

    The call out rates are defined in this document and the visit lead times vary from within the same week to two weeks advanced notice depending on current workloads.

    Customers who hold a Service Level Agreement ‘LuxCare Package’ with John Cullen Lighting directly should state this and will be given a priority call out response.

  • How far can I install my driver from the fitting?

    Governed by the driver manufacturers’ guidelines, we suggest up to 10 meters max. Should your drivers require placement further than this, your electrical contractor will need to work out the potential voltage drop that may occur on the type and size of cable installed to ensure that it matches the parameters of the driver such as forward voltages and wattage.

    In some instances, it is possible for the cable installed to be of a larger diameter to allow for a greater voltage drop within the driver parameters.

  • Can my lights be controlled via tablet or phone?

    All controls systems offered come with their own SMART phone/tablet standalone applications which allow for more flexibility in controlling the systems.

    Our controls team will go through how they operate in person and cover all the features that they offer.

  • Do you sell control systems?

    Yes at John Cullen Lighting we sell lighting controls in house and they are supported by our specialist controls and technical team.

    We offer controls for various scenarios in the home from Single room solutions to whole home systems.

    Working alongside respected brands Lutron, Helvar, Rako and Forbes & Lomax we have a solution that will suit your requirements.

    For any enquiries please contact the customer service centre on 020 7371 9000 or email

  • Can the control be integrated into other systems?

    All controls systems can be integrated into 3rd party controls systems (Crestron, Control 4 etc.).

    Our controls team will provide your systems integrator with the necessary information they require to make this happen.

  • Do you install control systems?

    All mains voltage and dimming control connections are to be installed by an approved electrical contractor with our controls team carrying out the setup of the system. We work closely in hand with contractors providing all necessary documentation, site visits and support.

    We can also arrange in house contractor training with our Demo Panels to ensure clarity all round.

  • What are LEDs?

    An LED is a semiconductor device that emits a visible light of a certain colour when an electrical charge is applied. They provide a very low heat source with a very long lamp life – around 50,000 hours.

    What defines the colour of the chip?
    Different material composition of LED Chip materials allow for a single colour from a huge spectrum of colours.

    Can an LED chip emit white light?

    How do we get white light for lighting?
    LED Chip manufacturers combine either a blue or UV emitting LED with a yellow phosphor.
    They can be used to introduce accents of colour or are ideal in situations where no heat is a requirement such as uplighters and floor washers where little fingers could be burnt. Linear versions can now be used for shelf lighting such as the Contour. They are also more energy efficient than standard halogen fittings which help in our efforts to be greener consumers.

    What are dimming LEDs?
    LED’s can be easily dimmed but require slightly different equipment and wiring. Most LED’s are 0-10v, this dimming requires a 0-10v dimmer module (which can fit in the JCL wall plates and dimmer plates) rather than a regular dimmer. Secondly 0-10v dimming requires a pair of cable to be connected to the dimmer module.
    Some LED drivers allow for the product to be dimmed on regular dimmers, however compatibility with the particular module needs to be checked.
    A DALI dimmer is the recommended dimmer for best performance. Click here to view our DALI dimmers.

  • What is the difference between current rated LEDs and voltage rated LEDs?

    Current rated LED’s require a constant current such as 350mA or 700mA, these LED products will also require a forward voltage that is specific for the particular LED being used in the product. A current rated LED needs to be specified with these two factors taken into consideration i.e. 4 x LED’s rated at 700mA with a voltage of 3.2vDC each will require a driver that produces 700mA with a minimum voltage of 12.8v. Current LED’s also need to be wired in SERIES.

    Voltage rated LED’s require a constant voltage such as 24vDC, these LED products will also consume a power (wattage) that is specific for the particular LED product being used. A voltage rated LED can be specified much the same as regular low voltage products i.e. having the required voltage (24vDC) and having a wattage output suitable to the amount of wattage consumption. Voltage rated LED’s also need to be wired in PARALLEL.

  • What are fibre optics and would you use them?

    These are created by a single light source located remotely in what is known as a light box. A special reflector focuses the light down individual glass fibres, usually enveloped in black sheaths, which emit light at their ends. They emit no ultra-violet rays and no heat. If side emitting, they have no black sheath and their entire length is lit. They are best used where a cool source of light is required e.g. walk over uplighters, water features, where maintenance is an issue e.g. swimming pool or in assessable spaces where very small light sources are required e.g. in cabinets, water spouts etc. and for the introduction of colour – a colour wheel can be used for a changing array of colours.

  • What is an IP rating?

    The system is used provide a guide to the degree of protection that a luminaire has against the ingress of solids and liquids.

    The First Number relates to solids and ranges from 0 –6.
    The ratings offer a logical progression from larger to smaller objects, so the lowest number (zero) indicates that there is no protection against touching live parts within the equipment. The most common rating for a light fitting intended for general interior use is IP20, which tells you that nothing larger than 12.5mm diameter can reach a live part when the equipment is fully assembled.

    The Second Number relates to liquids and ranges from 0 –9.
    Unlike the natural progression assigned to the ingress of solids, the second number relates to styles of liquid ingress; drips, sprays, splashes, jets and immersion.

  • What is a PIR?

    A PIR is a presence detector that can turn on a light circuit through the detection of a moving object. This can be used within bathrooms, porch ways etc.

  • What is the Colour Rendering Index?

    Colour rendition is the ability of a light source to accurately illuminate a colour compared to a reference source.

    How is this measured?
    The current method uses a reference pallet of 8 colours (R1-R8) called the Colour Rendering Index (CRI) developed by the CIE. Latterly an additional 6 (R9-R14) more saturated colours have been added but do not have to be referenced. CRI is stated in terms of a factor of 100 e.g. CRI80 or CRI 90 and is an average of colours tested (Ra).


    What is the future of Colour Rendition?
    The Lighting Industry has taken steps to move away from the CRI method as it is too limited and not a true representation of colour, especially with White LEDs.

    What is TM-30?
    The new TM-30 standard offers two metrics Colour Fidelity (Rf) and Colour Gamut (Rg). Colour fidelity is similar to CRI however references 100 swatches rather than 8.
    Colour Gamut is the average level of saturation relative to a reference illuminate (measured between 60 and 140).


  • What does the Correlated Colour Temperature mean in regards to LEDs?

    Correlated Colour Temperature (CCT) is reference to the colour of light emitted by a reference solid object (Black Body) as it gets hotter from red through to white. It is expressed in degrees Kelvin. The sequence of colours describes a curve within a colour space. This is shown in the diagram on the right.

    What do John Cullen Lighting Offer?
    The standard JCL colour offering is 2700K. However in our flexible strip range we also offer 2400K (a warmer colour).

    Why do we offer 2700K?
    Traditionally residential properties were lit with incandescent lamps which emit light with a colour of roughly 2700K.

    LED Colour Temperature


  • What is Colour Consistency in terms of lighting?

    Colour consistency in an index related to the light sources range of variation in chromaticity (colour) that can be picked up by the human eye.

    Why is this an issue for LED?
    During the manufacture of LED the colour, luminous flux and forward voltage can all vary. An LED is essentially grown and although accuracy of this has improved over time consistency is still an issue.

    How is colour difference measured?
    Colour difference is defined by a steps of MacAdamellipse. The scale is set by ANSI Chromaticity Standard. In short though the smaller the ellipse value (size) the smaller the colour difference.

  • How do LED chip manufactures manage variation?

    As there is no method today that offers 100% replication of a set specification, so the LED manufacturer measures each LED chip and separates them in separate groups (or bins) which are defined by each manufactures own coding system. In the diagram to the right 8Cis an example bin. At John Cullen Lighting we specify LED chips with the smallest bin possible to allow for consistency among the range.

  • What are the beam angles available with LEDs?

    The beam angles available are: Narrow (Under 20°), Medium (20°-35°) and Wide (35°-65°).


  • What is a Lumen?

    Lumens measure how much light you are getting from a bulb. More lumens means it’s a brighter light; fewer lumens means it’s a dimmer light.

    Lumens let you buy the amount of light you want. So when buying your new bulbs, think lumens, not watts.


  • What is Thermal Management?

    A common misconception is that LEDs do not generate heat. Although the beam emitted is cool they do, like any other light source, convert electric power in radiant heat. Lifetime of the LED Chip is directly linked to the operating temperature of the LED Chip (often expressed as Tjor Junction Temperature). Poor thermal management where the LED is operating above manufacture guidelines can also lead to colour shift.

    How does John Cullen manage the operating temperature?
    There are various methods of doing this, at John Cullen we use the body of the luminaire to draw heat away from the LED chip. We do this by carful material selection, considered produce development and by working alongside our subcontract partners who are able to virtually assess designs and physically test prototypes.

    How does this benefit you (our clients)?
    By fully testing our luminaries we are able to offer our clients information such as maximum ambient temperature the luminaire can operate in, so our clients can be assured of life time and colour consistency of their investment in our lighting.

  • Will dimmers or control systems save me money?

    Dimmers and control systems can contribute to a cost saving for electricity use as you only use the required amount of power required for the effect you are looking to create.

  • What is the cable thickness on long runs?

    Making sure you get the right cable thickness is the responsibility of the installer. Cable thickness must be calculated to avoid voltage drop. Calculations and cable tables can be found within the latest edition of the IEE wiring regulations.

  • How far do I need to remove insulation from the fittings and transformers?

    Most fittings require insulation to be removed from the drivers and fittings. Please check with the installation sheets for the specific product.

  • What does a transformer do?

    A transformer reduces the voltage from 240v to 12v. A traditional coil or toroidal transformer works very well for whole circuits of low voltage fittings, or for outside use. Electronic transformers are small enough to use per fitting and hide easily in most ceiling recesses.

  • What are Part L Building Regulations?

    Since April 2010, at least three in four light fittings in new and refurbished homes must be energy efficient (Part L Building Regulations). John Cullen’s range of energy efficient fittings are not only practical but also decorative and well-designed. They are ideal green solutions for anyone renovating a house.

    Our designers will always discuss regulation requirements but ultimately it is the client’s responsibility to ensure contact with their local authorities building control service inspector as they do vary from region to region, inspector to inspector.

  • Will the European lamp ban affect my John Cullen Fittings?

    Currently all John Cullen products fall within the current guidelines on efficiency – tungsten halogen bulbs are not included in the directive until 2018. However we do recommend transferring all of your lights to LED before the 2018 ban to spread the cost over time. LED lights do cost more however their value and lifetime worth is far less than halogen lights.

  • Which lamps are affected by the European Commission lamp phase out?

    The European Commission has ruled to stop the sale of certain types of inefficient lamps for household use in a series of dates up to 2016.  The lamps that this currently affects are those most commonly found within decorative fittings such as table lamps and pendants.

  • Do I need a burial sleeve with my uplighter?

    Sometimes it is advisable to use a burial sleeve. These should only be used when the integrity of the installation surface is unstable such as old plaster board or loose uneven ground.

  • How much recess depth do I need?

    Most JCL recessed downlight fittings require a ceiling recess depth of 120mm minimum. This allows room for the movement of directional fittings, and allows a good airspace around the back of the fitting for air ventilation and fireboxing if necessary and allows for easy installation of a transformer. Our collection of wall and floor recessed fittings have individual recess depth requirements – please refer to the specific detailed product information available.

  • Are your Drivers and Transformers compatible with Lutron, Crestron, iLight etc?

    John Cullen power supplies are compatible with all of the above systems, for advice on any other compatibilities please contact Sales on 020 7371 9000.

  • Do you sell bathroom lights?

    We sell recessed downlights, wall lights, uplights and steplights that are IP rated for bathroom use. Aside from these, many exterior fittings can be used within the bathroom to create more dramatic effects, including uplights and floor washers. There are government safety restrictions to the lighting that can be used in the bathroom which can be discussed with your approved electrical installer.

  • Do you sell decorative fittings?

    At JCL, we supply discreet light fittings which concentrate on the effect of light as we believe that good lighting should not really be noticed. We do not supply decorative fittings except for some wall mounted, bathroom wall lights and exterior wall lights. However, decorative wall lights or table lamps for example, when combined with other light sources, give a good balance of light to a space and can be very effective. We would always allow supplies for this type of lighting within our design service.

  • How can I light my artwork?

    There are many options that can be found in our artwork lighting section within our product pages. These fittings range from surface mounted, recessed to picture mounted. At JCL we have every option available to light artwork effectively and discreetly.

  • How easy is it to change the lamp?

    Several of our fittings, use a unique concealed ceiling ring for easy lamp changing. These ceiling rings stay permanently in place in your ceiling and there are no long coils of metal to manoeuver. When the lamp needs changing you just pull gently on the bezel of the fitting and the central lamp holding part of the fitting will move. This also enables you to change lenses very easily without damaging your ceiling. This ring works well with a more delicate lath and plaster ceiling and a description of installation is provided on a Specification Sheet.

  • What does layering light mean?

    Layering light allows you to make the most of architectural and interior features in a room.

    A simple example of layering could be in a bedroom. Pendants or downlights give a functional light, whilst the addition of a bedside lamp will open out the space and create a warmer, cosier atmosphere.

    Light sources can be positioned in or on ceilings, on walls at night, mid or low level and could also be recessed into floors or walls at low level.

    By adding dimmers to all lighting circuits you produce further combinations of atmosphere. Evening lights could have a 5 amp circuit on a warm soft level, while the functional light source is either off or very dimmed. For daytime, the functional lighting would be at a much brighter output.

    For a more detailed explanation of how to layer with light, see our news pages.

  • Where can I find an electrician?

    We do not employ electricians directly to install your lighting scheme. If you require an electrician, local government websites recommend the following organisations who run registration schemes for competent electricians.

    Recommendations from friends and family can be helpful. We can also supply a list of electricians which we can recommend for certain areas.

  • Do I need a plan for the lighting design service?

    A floor plan is always required to produce a lighting design, as we mark them up with the exact position, circuit number and lamp requirements for each fitting specified. If you do not already have one produced by an architect, estate agent or yourselves, you must have a site visit so that we can measure up the space for you. Any size plan is helpful, but a minimum scale of 1:50 is required to ensure all of the information marked is clearly visible to your electrician or contractor for installation.

  • What is the difference between a designer and a senior designer?

    All designers at John Cullen have been fully trained for lighting design. Senior designers just have more experience than designers, and therefore always work on listed or new build properties, as these types of developments either require greater detailing or adaptations.

  • How do I obtain technical or design advice?

    Our Product Pages allow you to click on the thumbnail for further information and notes, there is also a link on that page to our full technical notes in PDF format to download and print. The Effects & Inspiration pages allow you to click through to many products being used in the images.

    Also our Designers at the Showroom (020 7371 5400) would be able to help with any individual product or placement questions and our staff at our Customer Service Centre (020 7371 9000) can assist with any installation or suitability questions you have.

  • How does the design service work?

    Please refer to our Design Service page, click here to be redirected.

  • How do I work out how many lights I need?

    Our Lighting Design Team are trained on designing the best lighting scheme in your home/yacht to take full advantage of features and furniture layout.

    For more information on our Design Service click here.

  • Can you quote from a plan?

    Yes our Sales Team can quote from a plan. Click here for our contact details.

  • How long does a design take?

    If you are having a fee proposal put together you should discuss this with the designer. Depending on the scale of the project the turnaround time is usually around 15 working days.

  • Are your products covered by a warranty?

    Our LED products are designed with long lifetime in mind, allowing reliable thermal management. John Cullen Lighting currently offers a standard 2 year warranty on our products.

    Ask about our extended warranty that offers:

    – Products for both interior and exterior usage – up to 5 years

    We now also offer a Service Level Agreement, ‘LuxCare’®, which can cover extended warranties and can include maintenance visits for lighting and controls systems. To find out more about our SLA’s please contact our customer service centre on 020 7371 9000 or email

  • What are your company details?

    John Cullen Lighting
    Registered office: 9 Donnington Park, 85 Birdham Road, Chichester, PO20 7AJ.

    Registered in England no. 2222386
    VAT no. GB 468 9162

    For the office locations and contact details, click here.

  • What are your opening times?

    Customer Service Centre and Technical Advice
    London Office – Opening Hours
    8:30am to 5:30pm Monday to Friday
    (except Bank Holidays)

    Dubai Office – Opening Hours
    8:30am to 17:30pm Sunday to Thursday
    (closed on Bank Holidays weekends)

    Showroom and Design Studio
    London Showroom – Opening Hours
    9:30am to 5:30pm Monday to Friday
    10:00am to 4:00pm Saturday
    (except Bank Holidays)

  • How do I check the status of my order?

    Order status can be checked via the Customer Service Centre on 020 7371 9000.

  • How long will my order take?

    Orders may vary due to stock holding of particular products, it is always best to enquire with the Customer Service Centre for an estimated delivery time.

  • Where can I collect my goods?

    Goods can be collected from our Customer Service Centre in the UK:
    John Cullen Lighting, Unit 24, Talina Centre, Bagley’s Lane, London SW6 2BW

    UK customers only

  • Are you British Institute of Interior Design (BIID) accredited?

    John Cullen are proud to be an industry partner of the British Institute of Interior Design.
    The Institute is committed to encouraging and supporting creativity and competence in the field of interior design through facilitating best practice, practical professional support, development opportunities and education.

  • Are you Anti Copying in Design (ACID) accredited?

    John Cullen are a member of ACID (Anti Copying in Design), an organisation committed to raising awareness and encouraging respect for intellectual property within corporate social responsibility.
    We take copyright issues seriously and protect all of our designs with the help of ACID.

  • Are you Royal Institute of British Architects (RIBA) accredited?

    John Cullen have been accredited by the Royal Institute of British Architects (RIBA) to present Continuing Professional Development lectures (CPD) to architects and trade professionals.
    We offer a full range of CPDs for you to join one of our events or you can set up a time and date to suit your practice.

    To see the full range of CPDs and dates on offer, click here.

  • Who do I speak to for sales?

    The Customer Service Centre is open 8:30am to 5.30pm on Monday to Friday for Sales on +44 (0) 20 7371 9000. Alternatively email:

    Our Dubai office is open from 8.30am to 5.30pm Sunday to Thursday on +971 (0) 4 554 0488. Alternatively email:

  • Where can I send my payment?

    Payment can be made over the phone with the Customer Service Centre or alternatively posted to John Cullen Lighting, Unit 24, Talina Centre, Bagley’s Lane, London SW6 2BW.

  • Who do I write my cheque out to?

    Cheques should be made payable to – John Cullen Lighting

  • How do I pay my invoice?

    Contact the Sales office +44 (0)20 7371 9000 for UK or +971 (0)4 554 0488  for Dubai quoting your Client code and order reference.