Service
Frequently asked questions
Answers on ordering, delivery and lighting technology. If something is missing, reach us on +49 241 99001621 or at sales@wsulights.com.
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01 Ordering
Purchase, terms, account
Are there terms for business customers?
Yes. Electrical contractors, planning offices and resellers get quotes for larger quantities and free DIALux lighting advice. In B2B mode all prices are shown net. More on the page For Business & Trade.
Are there prices for larger quantities?
Yes, on request. For larger quantities our sales team prepares an individual quote.
Can I order as a business?
Yes. Register as a business and enter your company details. For larger quantities our sales team prepares a quote for you.
Do you calculate with or without VAT?
With the B2C / B2B switch at the top of the header, on mobile in the menu under “Customer group”. In B2B mode the shop shows all prices net. The calculation in the cart follows your customer account.
02 Delivery
Shipping, abroad, returns
How fast do you deliver?
WSU Lights brand items ordered by 3 pm on a weekday ship the same day. For items from other manufacturers, the delivery time shown on the item applies.
Do you ship abroad?
Yes, EU-wide as standard, worldwide on request. Orders from other EU countries with a valid VAT ID are invoiced net.
What does shipping cost?
Shipping costs depend on the weight of the order. You see the exact amount in the cart.
What happens with a return?
As a consumer you can withdraw from the purchase within 14 days. The details are in our cancellation policy in the footer. We do not grant businesses a voluntary right of withdrawal.
03 Planning
Photometric data, samples, consulting
Do I get photometric data (IES / LDT) for planning?
We can only provide photometric data where it exists for the item in question. Send us the item number at sales@wsulights.com and we will check it for you.
Can I order samples in advance?
You can request samples for projects so you can check colour, glare control and build quality before the series order. Request via sales@wsulights.com.
Do you take on the lighting design?
Yes. We calculate your area in DIALux, select the right luminaire and propose quantity and spacing. This is free even without a subsequent order.
Do you also advise on retrofits of other manufacturers?
Yes. For retrofits the existing installation is the starting point anyway. Based on your photos and plans we tell you what has to be replaced and what can stay.
04 Lighting technology
Colour temperature & colour quality
What does Kelvin (K) mean?
Kelvin (K) is the unit of colour temperature. The value describes how warm or cool the light appears. Low values around 2700 to 3000 K look warm white (yellowish, for hospitality, living areas, hotels). 4000 K is neutral white and the standard for offices, retail, practices and education. Around 5000 K the light looks cool white (industry, workshops, warehouses), above 5500 K daylight white (production, security areas).
4000K neutral white
Standard for offices, retail, practices and education. Good balance of warmth and clarity.
Which colour temperature suits which application?
Rule of thumb: the more concentrated the work, the more neutral or cooler the light. Living areas (homes, restaurants) get 2700 to 3000 K, offices and sales floors 4000 K, technical environments 5000 to 6500 K, outdoor lighting mostly 3000 to 4000 K. Within one building keep one colour temperature consistent, otherwise adjacent rooms look restless.
What does the CRI value (Ra) tell me?
The CRI (Color Rendering Index, stated as the general colour rendering index Ra) measures how naturally colours are rendered under a light source. Sunlight = 100. From Ra ≥ 80 rendering is sufficient for offices, retail and industry. For textile retail, photo studios, practices and museums we recommend Ra ≥ 90.
What is UGR and when does it matter?
UGR (Unified Glare Rating) describes the psychological glare of a luminaire. For screen workplaces DIN EN 12464-1 requires UGR 19 at most. General rooms without screen work need UGR 22 to 25, storage areas UGR 25. UGR is always calculated for a specific room and is not a property of the luminaire alone. We will tell you the manufacturer's reference figure on request.
05 Lighting technology
Output, lumen, efficiency
What is the difference between watts and lumens?
Watts (W) state the power consumption, lumens (lm) the emitted luminous flux. With LED the two decouple: a 36 W LED now produces about 3600 to 4500 lm, an old 60 W incandescent bulb only reached about 700 lm. Comparing by watts is therefore no longer meaningful for LED; lumens and colour temperature decide the choice.
What does lm/W (luminous efficacy) mean?
Luminous efficacy (lumens per watt) is the efficiency figure of a luminaire. Current LED panels reach 100 to 130 lm/W, high bays and tubes sometimes 150 lm/W and more. The higher the value, the less power for the same light. For retrofits lm/W is the decisive figure for the payback calculation.
How do I calculate how many luminaires I need?
As a rough estimate: required illuminance (lux) × area (m²) ÷ lumens per luminaire × loss and reflection factor (typically 1.3 to 1.7). For a reliable design we calculate your area in DIALux free of charge. From one sample room the rest can usually be extrapolated.
Which energy class do your luminaires have?
The EU energy class (since 2021) ranges from A to G and rates the efficiency of a light source. Where we have the energy class, it is shown as a coloured arrow right next to the price. If the arrow is missing, we will tell you the energy class and EPREL registration number on request.
06 Lighting technology
Design, protection & dimming
What does the IP rating mean?
IP stands for "Ingress Protection" and describes protection against solids and water with two digits. The common levels:
- IP20 touch protection, no water protection. Dry interiors.
- IP22 touch protection and dripping water at an angle. Interiors.
- IP44 splash water. Bathrooms, sheltered outdoor areas.
- IP54 dust protection and splash water. Damp rooms.
- IP65 dust-tight and water jets. Halls, wash rooms.
- IP66 powerful water jets. Outdoor installations, industrial washing.
- IP67 dust-tight and temporary immersion. In-ground fittings, areas at risk of flooding.
What is the difference between back-lit and edge-lit panels?
Back-lit panels have the LEDs directly behind the diffuser, which usually gives higher efficacy. Edge-lit panels guide the light from LEDs at the edge through a light guide plate, giving a slimmer build (often only 9 to 12 mm) but slightly lower efficiency. In both cases the cover mainly decides the UGR value: screen workplaces need a glare-controlled version, for example with a microprismatic cover.
Do I need an external driver?
It depends on the luminaire. Panels, high bays, floodlights, track spotlights and continuous-row systems usually have the driver integrated, in the housing, the adapter or the gear tray. LED strips and LED modules need an external driver, whose type depends on power, voltage and dimming requirement. If in doubt, we will tell you the right driver on request.
What does "dimmable" mean and which protocols exist?
A dimmable luminaire can be adjusted continuously in brightness. Common protocols: leading- and trailing-edge phase cut for simple residential installations, for LED mostly trailing edge, 1–10 V as the analogue B2B standard, DALI as a digital bus system for entire installations (addressable, groupable). If in doubt, we will tell you the supported protocol on request. Check compatibility with your controls, otherwise the luminaire flickers or only dims down to 20 %.
07 Warranty
Warranty, genuine products, lifetime
How long is the warranty?
Statutory warranty rights apply. Whether there is an additional guarantee and how long it runs is stated on the product.
Are these genuine branded products?
Yes. We carry genuine products from well-known brands and our own brand WSU Lights.
How long does an LED luminaire last?
Depending on the luminaire, 15,000 to 70,000 hours. At 12 h of operation per day that is about 3 to 16 years. Where the value is known, it is stated on the product.
What happens at the end of life?
Used LED luminaires are electronic waste and belong in separate collection, not in household waste. Ask us how to return old equipment.
Contact
Question not answered?
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