Dear Dave and fellow TREGers:

To my knowledge, at the present time, a telecom transformer that meets the 
requirements of UL1459 can be used in a computer (i.e. a modem card, we have 
many that are).  For Canadian approval, the transformer would need to meet 
CAN/CSA C22.2 No. 225 "Telecommunications Equipment".  

One major difference between UL1459, CSA 225, and UL1950, is that in addition 
to dielectric strength tests, UL1950 requires a minimum separation distance 
between primary and secondary circuits (creepage and clearance) whereas UL1459 
does not.

Of course, if the lifetime of your product is likely to go beyond April 1, 
2005, you may want to consider just going with UL1950.  All existing products 
that comply with the old standards (UL1459, etc.) may be sold until the year 
2005.    All new products on the market after April 1, 2000, will need to be 
evaluated to the new Bi-National standard, which is the third edition of 
UL1950/CSA 950.


Mel Pedersen                                    Midcom, Inc.
Homologations Engineer                          Phn:    (605) 882-8535
e-mail:  [email protected]              fax:    (605) 886-6752

----------
From:   Dave Spalding[SMTP:[email protected]]
Sent:   Monday, July 29, 1996 9:25 AM
To:     '[email protected]'
Subject:        Safety

Hi TREG -

We have the "opportunity" to purchase a cheaper transformer which will meet the 
requirements of UL 1459 instead of UL 1950.  I understand that we can comply 
with either standard until March 2000 or 2001 and UL 1459 is getting talked 
about around here.  Our product is an ISA card that will fit into a PC.  I 
would rather go with UL 1950 because the PC would be tested to that (right?), 
because I have heard that we would need to install a fuse in the front end to 
comply with UL 1459 and because UL 1950 is more compatible with international 
standards..  My boss is looking to save cost so he wants UL 1459 and answers my 
desire with the fact that we will have multiple boards (one for USA/Canada, one 
for international), so we could use this transformer for the domestic board, 
although the issue of whether Canada would accept UL 1459 is not resolved. 
Also, the "fuse", he says, would be the etch on the board because they would 
just peel off with the overvoltage testing  of UL 1459.  I am not comfortable 
with that, though.  Anyway, I want to go with UL 1950 but I need ammunition.  I 
was wondering if you could help me understand the difference between UL 1459 
and UL 1950 and also give me your recommendation on which to test to.  Any help 
that you can give would be greatly appreciated.  Thanks in advance.

- Dave Spalding


David Spalding
Motorola ISG
20 Cabot Boulevard
M2-250
Mansfield, MA 02048-1193
Phone: (508) 261-4742
FAX: (508) 339-2346
EMail: [email protected]

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