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After a lot of warnings about measurements with non-proper instruments or in non-standard conditions, we would like to show you part of the referring normative (60335-2-27 A1 pg.13) in which modalities through which you can measure are indicated.

All the measuring which do not respect the modalities here describer are not valid and not important for certification. We also remember that any technical modification to adequate must be realized by the producer or its technicians.



Appliances shall not present a toxic or similar hazard. Appliances having UV emitters shall

not emit radiation having a total effective irradiance exceeding 0,3 W/m2 weighted according

to the erythema action spectrum of Figure 101.

Appliances shall comply with the values specified in Table BB.1.

Compliance is checked by the following test.

The appliance is provided with UV emitters that have been aged by supplying them at rated

voltage for a period of

– 5 h ± 15 min for fluorescent lamps;

– 1 h ± 15 min for high-intensity discharge lamps.

NOTE 1 A high-intensity discharge lamp is an electric discharge lamp in which the radiation-producing arc is

stabilized by the wall temperature and the arc has a bulb wall loading in excess of 3 W/cm².

The appliance is supplied at rated voltage and operated for approximately half the maximum

exposure time allowed by the timer. The irradiance is then measured at the shortest

recommended exposure distance, the measuring instrument being positioned so that the

highest radiation is recorded. However, the irradiance of facial guns is measured at a distance

of 100 mm ± 2 mm and calculated for the recommended exposure distance.

The exposure distance of UV emitters that are located over a person is the distance between

the emitter and the supporting surface, reduced by 0,3 m.

NOTE 2 The measuring instrument used measures the mean irradiance over a circular area having a diameter not

exceeding 20 mm. The response of the instrument is proportional to the cosine of the angle between incident

radiation and the normal to the circular area. The spectral distribution is measured at intervals of 1 nm by means

of a spectrophotometer having a bandwidth not exceeding 2,5 nm .

NOTE 3 For appliances having upper and lower radiating surfaces, each part is measured separately while the

other part is covered or removed. If the distance between two radiating surfaces is less than 0,3 m, the

measurement is made at the surface of the upper panel.

Appliances shall have a total irradiance not exceeding 0,003 W/m2 for wavelengths between

200 nm and 280 nm and measured by a spectroradiometer between 250 nm and 280 nm.

NOTE 4 The total effective irradiance is given by

Formula calcolo irradianza solarium


E is the total effective irradiance;

Sgamma is the relative spectral effectiveness (weighting factor) according to Figure 101;

Egamma is the spectral irradiance in W/m2nm;

DeltaGamma is the bandwidth in nm .




The normative is very strict as far as the measuring methods are concerned, fundamental factor to guarantee legacy and precision of the same. The measurement of a light spectrum leads to notable variables which can be influent on the results in a determinative way.

In particular, the normative states that:

-          The device has to be feed by the nominal tension

This feature, often not underlined, can change the emission of a lamp. With an over voltage or a sub voltage, the lamps can profit the 30 % in the emission of the UV.

SUGGESTION: Before making the measurement, use a tension line voltmeter to make sure that it is line with the norms. The results obtained during the test are realized with stable tension.

The aging of the devices must be standard

The aging (the hours that the bulbs have been lighten) of the lamp (intended as bulb or truck) influences on the emission. The normative is very specific and it states that aging must be:

-          5 hours for fluorescent lamps (low pressure lamps) with a maximum gap of 15 minutes (more or less)

-          1 hour for lamps of high intensity (high pressure lamps) with a maximum gap of 15 minutes( more or less)

SUGGESTION: Before making the measurement check the hours of the lamps placed on the device and check if they respect the values. If they do not, change the lamps, age them for the indicated time and repeat the measurement.

The distance must be calibrated

The normative accurately describes the position of the probe which makes the measurement. The precision indicated is clearly incompatible with measurements made holding the probe in the hands.

The probe will be placed with a static support at the indicated distance (the distance indicated in the book of the device); or at the distance of 10 cm, with a gap of 2mm, on facial devices (called bronzing pistols). The distance is a determinant factor in the measurement and it can change the value till 300 %.

SUGGESTION: The measurement must be made using a stand and the distance must be taken with a caliper in order to guarantee the correct distance.

The instrument must be adequate

All the measurements must be carried out with a precise instrument. To achieve this goal, the 60335-2-27 a1 specifies the use of a spectophometer   which can measure with range gaps not over 2,5 nm. The suggested measurement must be carried out with range gaps of 1 nm. This excludes luxometers or other portable devices which give the results of the emission. Spectroradiometers are good since they are part of the spectophometer family.

SUGGESTION: The measurement cannot be considered valid if carried out with instruments which only give a total value without explaining the energy on every nanometer. Usually they are portable devices called UVameter and Luxometer (not valid)

Lastly  some further suggestions:

-the measurement must be carried out starting from the half of the maximum planning time (e.g: maximum time 30 minutes, the measurement must be made only after 15 minutes). This is because the bulbs might have an energy peak in the first few minutes of functioning, faking the measurement.

-the measurement must be done according to the erymathogen action curve and not the non-melanoma one.

-the device must be cleaned in all its parts (filers and impellers). If the temperature  of the lamps is  over the standard, they might modify the emission, so as the dust in the filters.

We are available for any other further information.

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