Hi Kyle:
> I have a new product that includes an off the shelf UPS that is rated for
> 230V ac operation and has an internal single pole circuit breaker on the
> mains inlet. We want to target this product world-wide. The UPS presently
> is CB and certified to EN60950 european only. For North America we want it
> to have UL1950, and to obtain this, UL is demanding the breaker be double
> pole.
This is an unusual situation.
On the one hand, the UPS, with single-pole overcurrent
protection, has a CB to EN 60950 for use in Europe where
most mains supply plug configurations are non-polar.
There is no control that the overcurrent protection will
be in the live conductor.
On the other hand, the UPS, with single-pole overcurrent
protection, is denied UL certification for use in the
North America where UL requires polarization of both
the UPS overcurrent protection and the mains supply plug
configuration. There is a reasonable control that the
overcurrent protection will be in the live conductor.
There is indeed something wrong with this picture.
My guess is that the certification engineer is invoking
Table 1, Case B (UL 1950, 3rd). (As someone had already
suggested, you should verify this with your certification
engineer.) Probably, this is because he knows that you
are marketing your product worldwide.
Since you have a CB, you are qualified for Case B
independent of your UL certification. You should point
this out to your certification engineer.
I would ask UL to investigate the product under Case A.
UL can, at its discretion, investigate products to
specific provisions of their standard. UL can invoke
paragraph D of the UL foreword to the standard. You
can even ask UL to so note this construction in the
UL report.
In my experience, these proposals should get you around
this situation.
If you are still unable to use the single-pole overcurrent
protection, I would go to another NRTL.
Good luck, and best regards,
Rich
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