[SI-LIST] Re: threshold

There is something like a 70VDC maximum although I was thinking that =
some agency has a 50V max. Notice how that conveniently allows -48V from =
another discussion to be okay. However, as I recall, the -48V in telco =
systems is not highly regulated so the 70V limit would allow for the =
voltage excursions.

But beyond the voltage limit, there is also a power limit of 250VA. This =
makes sense when one considers that you can make a nice arc welder or =
lightning generator at low voltage if you can generate enough current.

All this means that you should check with your regulatory bodies to =
ensure that you'll pass testing/certification.

-----Original Message-----
From: Larry Barnes [mailto:larry.barnes@xxxxxxxxxx]
Sent: Wednesday, 30 July, 2003 08:08 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: threshold


As I recollect from my days in designing power supplies, there was a =3D
SELV (safety extra low voltage) that the registering agencies such as =
=3D
Underwriters Laboratories (UL), CSA etc. specified and it was somewhere =
=3D
around 40 volts.  Casual contact by untrained personnel was not =3D
permitted on any voltages exceeding the SELV.  You may want to check the =
=3D
UL, CSA etc standards to se if this has changed.  I think the idea was =
=3D
that any current with a voltage lower than SELV behind it was not =3D
supposed to be lethal.



-----Original Message-----
From: hariharan [mailto:hariharan@xxxxxxxxxxx]
Sent: Wednesday, July 30, 2003 6:44 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] threshold


what is the threshold  Voltage (V) and current (amps) beyond which human
beings can get hurt or feel it?

any idea...??




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