I do not know about T7S series but T7N is similar. As long as the
creepage distance and clearance fulfill the standards, it
is okay to be used. In T7N's case, the common contact pin is put
between the coil pins. This is quite unusual but it is still 
okay (6mm from the center hole of the common pin to the coil pins,
normally 5.5mm is required for double insulation and 3mm for 
basic insulation). It is also okay to be used for UL since
it is recognized by UL.

It can not be used in Protection Class II equipment though. 
I am now using Schrack PE014 relay for Protection Class II. 
It is one of the smallest which fulfill Protection Class 
II (Overvoltage category III and reinforced insulation,
voltage rating 250V according to IEC60664). The isolation
voltage between relay coils and contacts need to be
greater than 3750V RMS in order to be used in Protection 
Class II.

Maybe one big customer of T7N/T7S series requires Tyco/Scrack
to do this. 

EN50178 and UL508/UL840 are good to read in terms of isolation
requirement. It is not so fun to read though.

Regards,
Xiaofan

-----Original Message-----
From: laura capaldi 
Sent: Friday, October 07, 2005 10:28 AM
To: piclist@mit.edu
Subject: [EE] Pinning in newer relays

I was looking at some of the new Tyco/Schrack relays, the T7S series. 
Anyone know why they've moved one of the N/O pins up to in-between 
the coil pins. Won't this be dangerous if using mains currents 
between the N/O pins? Why change it from the original coil pins 
on one side and N/O pins on the other?
 
Laura

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