Legal
Terms of use
Plain version: the notes and calculators here are reference material, not engineering advice for your building. Check the output before you rely on it.
Last updated: August 2026
1. Who publishes this site
elklotusled.com is published by Long-Term New Media Limited, registered in Hong Kong, trading in lighting products under the Elk Lotus LED name. Using this site means accepting these terms.
2. The guidance is general, your project is not
Everything here is written for a general reader and cannot account for the conditions of a specific installation — the building, its occupancy, the electrical infrastructure, the fire and emergency strategy, or the regulations of your jurisdiction.
Lighting design for an occupied building is regulated work in most jurisdictions and needs a qualified engineer engaged on your project. Anything touching emergency lighting, egress, fire strategy, or mains electrical installation must be designed and verified by someone competent and appropriately insured. Nothing on this site is a design, a certification, or a substitute for either.
3. Calculators
The calculators run entirely in your browser; no input you type is transmitted to us or stored on a server. Each one shows the formula it applies and the assumptions built into it.
They implement standard published methods — the lumen method, voltage drop by conductor resistance, simple payback — using the inputs you supply. Their output is an estimate that depends completely on the accuracy of those inputs, and they deliberately ignore factors that a real design accounts for, including obstruction, non-rectangular rooms, daylight contribution, control strategy, and ambient temperature effects on output. Treat the result as a sanity check on somebody else's proposal, not as a design.
4. Standards and third-party material
Where we refer to EN, IEC, CIE, GB or IES documents, we describe and cite them. We do not reproduce their tables or text, which remain the property of the relevant standards bodies and must be obtained from them. Our description of a standard is our reading of it and has no official status; the published document governs.
Where a figure from a manufacturer's datasheet appears, the manufacturer and document are named. Trademarks and product names belong to their owners and are used for identification only.
5. Our content
The text, tables, diagrams and calculator code on this site are ours. You are welcome to quote a reasonable extract with attribution and a link. Republishing pages wholesale, with or without modification, including feeding them through a rewriting or translation process to produce derivative pages, is not permitted.
6. No warranty
The site is provided as is. We work to keep it accurate and review pages on the dates shown, but we do not warrant that it is free of error, complete, or current with the latest revision of any standard. To the extent permitted by law we exclude liability for loss arising from reliance on this material — which is the formal way of saying: verify anything that carries cost or risk before acting on it.
7. Advertising
This site carries advertising served by Google. Advertisements are selected automatically and are not endorsements. No advertiser reviews or approves editorial content, and no page here is a paid placement. Data collection associated with advertising is described in the privacy policy.
8. Changes
These terms may be updated; the date at the top changes when they are. The governing law is that of the Hong Kong Special Administrative Region.