Electronics > Projects, Designs, and Technical Stuff

CE marking - Minimum size of ventilation holes

(1/3) > >>

ciccio:
I've a problem with the CE marking of a professional power amplifier that has a forced air cooling.
An engineer at the conformity assessment laboratory says that, to comply with regulations about fire propagation, the  ventilation apertures must have a maximum size of 1.0 mm. 
In the prototypes these apertures are:
- some slits on one  side, for cool air input,  about 3 x 100 mm each (the case is made of 1.2 mm steel, and it is not possible to punch it with a die smaller than 2.5- 3.0 mm or the sheet will be deformed).
- the exhaust fan, low voltage DC, with finger guard. A screwdriver inserted there will  touch only low voltage parts.
I test and open everyday professional equipment that has similar construction, and I do not see any aperture smaller than 3 mm (this size assures safety against contact with dangerous internal parts), and the chrome wire fan guard is standard.
Where is the catch? 
Is there any expert member that can give me an opinion?
I'm waiting for a mail message that reports the point of the regulations that require this, but I want to be ready for an answer, and cannot find any information on the  subject.

amspire:
I am not an expert on the CE rules, but CE is basically a mass of directives and guidlines that you may or may not have to comply with in a particular case.

So you need to ask the engineer which directive or guideline requires the 1mm maximum aperture size, and why you need to comply with that directive or guideline in your particular case.

I would imagine that your equipment has to meet the requirements of the LVD (Low Voltage Directive), just like PC power supplies (which have apertures bigger then 1mm) , unless you indicated uses of the amplifier that exclude the LVD like medical uses or uses in an explosive environment.

ciccio:
The applicable standard is IEC 60065 / 2001 amendment 1 / 2005:  "Safety requirements for Audio Video and similar electronic apparatus"

The standard defines a FIRE ENCLOSURE as "part of the electronic apparatus intended to minimize the spread of flames from within".
It goes on about resistance to fire, saying that the equipment must:
use good engineering practices to prevent the start of fire AND use low flammability materials in the vicinity of potential ignition sources AND use FIRE ENCLOSURES to limit the spread of fire.
Later on FIRE ENCLOSURES are defined as having ventilation holes of a maximum diameter of 1 mm.

I'm sure the engineer at the test laboratory got confused by this, because FIRE ENCLOSURES are, in my opinion, something that is used to enclose part of the internal circuitry or components that may start a fire in normal or faulty condition, and if no such sources exist because of their nature or because a protective circuitry is used, then there is no need for them,  but the standard is, in fact, not clear at all....
She (the lady engineer) insists that there must be a FIRE ENCLOSURE because of the AND  written before, and if this FIRE ENCLOSURE is not inside then the whole cabinet is the FIRE ENCLOSURE...
If this 1 mm rule is applicable to the cabinet ventilation holes there should be no need for the minimum 3 mm rule that applies to ventilation holes...

amspire:
I believe the FIRE ENCLOSURE is relevent only for parts of the circuit operating above 4kV.

See http://www.ul.com/global/eng/pages/offerings/industries/hightech/consumerelectronics/pag/

FreeThinker:
Could you not cover the ventilation holes with some sort of fine mesh or filter to comply?

Navigation

[0] Message Index

[#] Next page