Piotr, It sounds like your management are asking you to achieve the impossible.
There are many different aspects to achieving compliance with CE marking directives and what is more there are many more directives to be complied with which do not require the CE marking that are either in force now or will be coming into force in the near future (such as those that relate to protecting the environment). It would take a very long Email to list all these requirements and I am not going to try. You, on the other hand, need to find out what EU Directives apply to your product before instigating any design changes. From knowing what EU Directives apply you can then decide what standards to apply. Although you presently seem concerned about one aspect of your design, in fact there may be many other matters to consider. For example, for safety, if your case is made out of plastic then you will need to consider meeting the flammability requirements: but if your case is metal then there are earthing requirements to consider. So, my recommendation is for someone in your company to take a step back and determine a COMPLETE list of requirement that apply. While your company has an obvious desire to meet EU requirements for all its existing products as soon as Poland's entrance into the EU, in practice this may not be possible if the number of changes are too large for your design team to investigate and implement. Regards, Richard Hughes Safety Answers Limited www.safetyanswers.ltd.uk In a message dated 02/08/2004 03:16:48 GMT Standard Time, [email protected] writes: Richard, Once more to the same mail: My system is the access control system (not heavy industry). If my device is 12V powered (installer selects the poker supply - I think standard as for alarm systems with Accu in it). I wrote in instruction that RS485 connection is allowed only in one building (the 1km is because all must be in series). Shell I consider in any way the safety ? If I will be surge protected is enough ? I was worrying if I am allowed to connect my PCB ground to protection ground with 100 Ohm. It can help reduce the ground differences for RS485, but directly to my PCB ground can be connected for example door lock coil powered >from the same poker supply. I consider poker supply fail and 230V goes to DC output. If -12 is well grounded - breaker should do its job. But if not - the 230V can go to the door metal frame (door lock coils are not well isolated I think). 1 kOhm is nothing if somebody has no differential breaker. Is it my problem or I should only select that the poker supply must be certified to .... ? I have read a lot about EMC and nothing about safety. I will read EN 60950-1 and may be there is the answer. In some industry controller instruction I have read: "It is the extra low voltage device and can be installed as isolated or as grounded". It was powered from 12 or 24V (not sure). What this sentence was about ? Regards Piotr
