Triple Plating an Isolator

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JamieP
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Triple Plating an Isolator

Post by JamieP »

Just for arguments sake because I'm pretty damn certain this is absolutely not ok because it defeats the wholesaler purpose of a device for isolation by still having live parts in the device after the isolator is off but I have a number of people arguing it's ok

So, what's your opinion? Is this ok? Or absolutely not?

For further reference the actual situation it's being done in is in PV installs where there inverter has a removable section for maintenance and repair, because there is external isolation device the DC is always live in this compartment so there argument is that the external AC isolation device they have installed is fine to be triple plated due to the live parts of AC also contained in this compartment

Furthermore under current rules as covered in a earlier post this external AC isolation device technically doesn't even need to be there, as it's actual isolation device is at the switchboard, could this also change things due to the secondary device not actually being needed for isolation so simply used as a functional switch that triple plating could be acceptable practice
AlecK
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Re: Triple Plating an Isolator

Post by AlecK »

please define what you mean by "triple plating" in this context
JamieP
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Re: Triple Plating an Isolator

Post by JamieP »

The feed runs direct to the location of the device

Just the active is run from this location and back through the switching device

With the switch off the feeding conductors are still live in the device
AlecK
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Re: Triple Plating an Isolator

Post by AlecK »

That's OK for a functional switch; but not for a required isolating switch.
Isolation is defined [1.4.62 of "3000"], so a required isolating device has to perform that function as defined.
If it doesn't remove "every source of energy" in the manner set by the requirement calling for it; then it isn't isolating.

The "main switch" for the inverter supply to the installation [ 3.4.1 of 4777.1] must be at swbd connected to.
The additional isolating switch required by 3.4.3 (where the IES is not adjacent to the swbd) has specific requirement not to be within the "operational portion" of the IES; and this is stated to be so that it remains in place if the inverter is removed from service.

The clear inference is that this additional isolator only has to isolate the "operational portion", and need not necessarily isolate the base into which the "operational porting" is fitted.
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