Street lighting upgrade: HPS 250 W to LED

On the poles along streets, plant driveways and fuel station grounds in Uzbekistan stand bracket-mounted road luminaires with HPS 150 W and HPS 250 W lamps. An upgrade here is rarely a “luminaire for luminaire” replacement: the street is calculated from its category and the norm, and it is the recalculation that delivers most of the gain. Targets, the series and a typical layout are on the street lighting page.

Street category and the norm

The Uzbek building code ShNK 2.01.05-24 (table 15) sets street lighting by the average luminance of an improved surface and, as an alternative, by the average horizontal illuminance. The category depends on traffic intensity:

• category A: 0.8 to 1.6 cd/m² or 15 to 20 lx;
• category B: 0.4 to 1.0 cd/m² or 10 to 15 lx;
• category V, including service roads: 0.2 to 0.4 cd/m² or 4 to 6 lx.

Factory forecourts: 10 lx; pedestrian streets: 4 to 6 lx (table 16). Uniformity: the ratio of minimum to maximum luminance no lower than 0.4 (clause 93). For a street this matters more than the average: a driver sees the dark gap between poles, not the extra lux under a pole. The maintenance factor for streets is 0.63 to 0.67 (app. 1, table 3).

What is installed now: HPS on the pole

An HPS 250 W (SON-T) lamp with ballast draws 275 W (250 × 1.10 under the EU energy labelling convention for discharge lamps; at the minimum ballast efficiency it can be 294 W). The flux of a new lamp is 30,000 lm (Lisma DNaT 250-5M); by 16,000 hours the lamp must retain 85% (EU Regulation (EC) No 245/2009, table 13). HPS 150 W: 165 W and 15,750 lm.

Yellow light with Ra around 25 does not let you tell the colour of a car or a pedestrian’s clothing, and a round reflector shines in all directions: part of the flux goes into the windows of houses and into the sky, not onto the road surface.

Why one-for-one does not work

The bracket-mounted SKU 01 Classic 100W street luminaire: 100 W, IP65, mounting height 2 to 12 m. Flux by the header of the 2018 IES file is 13,000 lm; the file itself does not agree with its own curve, so the figure is calculated, and the model page says so.

Against HPS 250 W a one-for-one replacement gives 64% less power, but also 57% less flux by the lamp rating. The calculator has to show a warning here. On a driveway, however, that warning often does not mean a shortage of light.

A typical plant driveway: ≈ 800 m long, 7 m wide, 8 m poles, 30 m spacing, category V. 27 HPS 250 W give ≈ 30 lx at rated flux, ≈ 27 lx by 16,000 hours. The norm for category V is 4 to 6 lx, for category B at up to 500 vehicles an hour 10 lx. The old scheme is over-lit 3 to 5 times, because it was calculated from the lamp that was in stock, not from the norm. 27 Classic 100W by the flux-per-span method (UF 0.35, MF 0.63) give ≈ 14 lx: the norm is met, not exceeded several times over.

In kilowatts: ≈ 7.4 kW against ≈ 2.7 kW, ≈ 4.7 kW freed. At 11 burning hours 365 days a year that is ≈ 19,000 kWh a year; at a tariff of 1,100 UZS per kWh including VAT (Cabinet of Ministers Resolution No. 243 of 15 May 2026), ≈ 20.8 million UZS. A calculation for a category B street with heavy traffic will give a different spacing and possibly a different model; the calculation by road class decides, not a table saying “put 100 W instead of 250 W”.

What the recalculation gives beyond kilowatts

• Freed capacity. At a street lighting substation it is often needed for new poles on neighbouring streets or for CCTV without laying a new line.
• Uniformity. The light distribution curve is recorded in the IES file, and DIALux shows the minimum between poles before procurement, not after installation.
• No depreciation and no lamp replacement. HPS has a rated life of 24,000 hours by catalogue, which at 11 hours a day is 6 years, and replacing a lamp on a pole means an aerial platform and a closed lane.
• Operation in the heat. A housing in the sun goes above +70 °C; the extruded aluminium housing of Classic works as the heat sink, and the operating range in the data sheet is -30 to +50 °C.

An example from practice: a fuel station in Tashkent, 18 HPS 250 W lamps on the grounds and under the canopy, ≈ 5 kW. 12 Classic 100W were installed on the poles and 24 Line 50W under the canopy: ≈ 2.4 kW, calculated ≈ 170 lx against ≈ 80 lx where the light is needed. Total lumens went down, light at the entrance went up. The figures are estimates; we have no measurement record.

Documents for a state customer

Street lighting is most often procured by khokimiyats and utility enterprises. For them, Presidential Resolution No. PP-4422 of 22 August 2019 (clause 8(b)) has required LED light sources at facilities on their balance sheet since 1 January 2020. The pack we supply for a lot:

• a DIALux calculation by road class with luminance and illuminance isolux contours;
• IES files for the model and a data sheet with the operating temperature range;
• a declaration of conformity under Cabinet of Ministers Resolution No. 43 of 30 January 2021 (app. 4, clause 107);
• a 36-month warranty letter;
• documents on production in Tashkent; the certificate of locally manufactured goods under Cabinet of Ministers Resolution No. 712 is provided on request.

A technical specification template for street lighting without trade marks (Law No. ZRU-684, article 34, part 3) sits on the page for state customers. An estimate for your own poles, hours and tariff can be made in the savings calculator.

The calculated saving holds under the stated assumptions and is not guaranteed until measured on site. Figures marked ≈ are estimates.

Frequently asked questions

Which LED luminaire replaces HPS 250 W?

It depends on the street category, carriageway width, pole height and spacing. For a category V driveway with 8 m poles at 30 m spacing the calculation meets the norm with Classic 100W. A category A street needs a calculation by surface luminance, and the model is chosen from it.

Can the poles and brackets stay as they are?

Classic mounts on a standard road luminaire bracket. The calculation takes the pole height and spacing as they are; if uniformity under clause 93 fails at the existing spacing, it shows in DIALux before procurement.

How to check the result after installation?

A lux meter measurement on the road surface over a grid between two poles at night, compared with the calculation: at acceptance ShNK 2.01.05-24 (clause 178, table 26) allows no less than 90% of the design level. The saving is confirmed by the substation meter for a month before and after.

Do you have a measurement report for the luminaire?

There is no LM-79 test report on the assembled luminaire yet; take the flux from the IES file and the calculation. A 3-year warranty, production in Tashkent since 2014.