A Notified body should figure out what is required and what is
not required not your boss. Under the TTE directive TTE
equipment must be approved by a Notified Body to be marketed in
the EU, if I understand the rules that is. If you were unable
to find a Notified Body to agree with your safety assessment you
would have a delay in your product.
Regards Ian.
In message " BS EN 41003: 1997 now available" sent on Feb11,
[email protected] writes:
>Jon D Curtis wrote:
>
>> Doug:
>> At least in Spain, public switching telephonic network works
with 48 V =
>> dc but the ringing signal could reach 75 V ac (hazardous
voltage =
>> according to LVD). In fact, if you catch both poles of a
telephone line =
>> during the ringing process, you will suffer that voltage. So
for that =
>> reason, LVD applies.
>
>Gee, I hate to disagree with you Jon.
>
>I'm not supporting the argument I'm presenting. It was used
>by a former boss to a great extent. More like a little
>knowledge is a bad thing, especially when marketing gets a
>hold of something like this. It was a battle.
>
>The ring signal of which you speak is in what I've known
>as the 'local loop' between [I believe] a Class 5 office
>[last in line before the subscriber] and the subscriber on
>the analog line. The ring signal is handled *sometimes*
>[because I'm not 100% sure] by a *channel bank*. There are
>analog and digital channel banks. Some that I'm familiar
>with control the interface between the T1 line and the
>ring voltages out to the subscriber. A T1 line by spec
>cannot handle the ring voltage.
>
>Now, if your product is a T1 IMUX device or a DCS device
>*behind* a channel bank, that is to say not on the
>subscriber side of the channel bank, the IMUX or DCS device
>handles only 48vdc power [and sometimes 24vdc] and the
>T1 signal levels.
>
>Now for Europe, substitute the above use of T1 with E1,
>remove the Bell term "Class 5 office", and the scenerio
>is very much the same. I would appreciate any corrections
>here.
>
>So the voltages handled by this E1 device are:
>
> a power supply of 48vdc and
>
> the signals as defined in G.703
>
>There are no voltages anywhere near the 75vdc lower
>limit of the LVD as defined in 73/23/EEC, Article 1.
>
>So, the conclusion could be any telco device powered
>by 48vdc and only handling E1 signalling is NOT
>covered by the LVD - 73/23/EEC.
>
>This same argument was used by my former boss to try
>circumventing UL testing, i.e. 48vdc being in the SELV
>and NOT a hazzard.
>
>I got him nailed on both T1 and E1 devices by pointing
>out that safety testing of a device is not solely dependent
>upon normal use voltages. It is used to test the device
>for overcurrent overtemp overvoltage abnormals, ground
>currents ... conditions for safe operation attested by an
>independent third party.
>
>Comments.
>
>************************************************************
>------------------------------------------------------------
> The comments and opinions stated herein are mine alone,
> and do not reflect those of my employer.
>------------------------------------------------------------
>************************************************************
>
