Mains fuses and OVER-CURRENT RELEASES

blindalien

Registered
8.11.5 * Mains fuses and OVER-CURRENT RELEASES
A fuse or OVER-CURRENT RELEASE shall be provided in each supply lead for CLASS I ME EQUIPMENT and for CLASS II ME EQUIPMENT having a functional earth connection according to

8.6.9, and in at least one supply lead for other single-phase CLASS II ME EQUIPMENT, except that:
– for PERMANENTLY INSTALLED ME EQUIPMENT, the neutral conductor shall not be fused;
– if examination shows that two MEANS OF PROTECTION are present between all parts of opposite polarity within the MAINS PART, and between all parts of the MAINS PART and earth, then the fuses or OVER-CURRENT RELEASES may be omitted. These insulation requirements shall be continued up to and within any component. The effect of short-circuit fault
conditions in other circuits shall be considered before eliminating fuses or OVER-CURRENT RELEASES.

A PROTECTIVE EARTH CONDUCTOR shall not incorporate a fuse or OVER-CURRENT RELEASE.

Protective devices shall have adequate breaking capacity to interrupt the maximum fault current (including short-circuit current) which can flow.


For our Class 1 device (which is a 110-120V 50/60Hz 1100W blower) we are adding a fuse holder with a F, 12A, 10kA, 125V fuse on the hot wire. In the literature it makes it sound like we would have to add a fuse to the neutral wire which seems absolutely pointless. I asked a safety reviewer at the company we are going to get our device tested and he said "A over current device has to provide in each supply lead (the line & neutral conductors)". How could we possibly bypass this and have a fuse just on the hotwire or is there no way to bypass this?
 

Ninja

Looking for Reality
Trusted Information Resource
– for PERMANENTLY INSTALLED ME EQUIPMENT, the neutral conductor shall not be fused;

– if examination shows that two MEANS OF PROTECTION are present between all parts of opposite polarity within the MAINS PART, and between all parts of the MAINS PART and earth, then the fuses or OVER-CURRENT RELEASES may be omitted.

I am not in medical equipment.

That said...more info needed...

Is your equipment permanently installed?
If not, what are your two means of protection?

If the answer is "no" and "we have only one"...the answer seems sorta clear...
 

3dBUnderThe Limit

Starting to get Involved
I think that the point is that unless you have a fixed installation you don't know what wire in your equipment is "hot" => fuses in both leads for a Class I Medical Device. (unless 2 MOP "everywhere").
 
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