ADS has been assumed ... but does the system and connected equipment use something else ... double or reinforced insulation, for example?

Agreed - or even separated - either for one item (see BS 7671 section 413)  or several (section 418.3).

Is whatever is connected to the secondary side of the PSUs fixed? If it's just a socket outlet that anything could be plugged into, the secondary side might not come under BS 7671 anyway (like a lot of smaller UPSs) but come under some equipment standard that may have its own ideas about shock protection (the basic principles are likely to be similar to BS 7671's but sometimes the significant details can vary). I've a feeling that 400Hz is slightly safer than 50/60Hz from a shock perspective too - which again might influence some details.

   - Andy.

AJJewsbury said:

or even separated - either for one item (see BS 7671 section 413)  or several (section 418.3).

Possibly ... I was also thinking that we don't know what these supplies do, and therefore whether they are part of the electrical installation (under BS 7671) or machinery as defined in the Supply of Machinery (Safety) Regulations (under BS EN 60204-1) ... but that doesn't really affect the classification.

Hello,

Thank you for your replies.

gkenyon said:

ADS has been assumed ... but does the system and connected equipment use something else ... double or reinforced insulation, for example?

ADS is assumed because the 400 Hz power supply feeds multiple items of class I equipment and the exposed conductive parts of these items are not isolated from the exposed conductive parts of other circuits and also have fortuitous connections back to facility PE via the local metalwork which is connected to the MET.

AJJewsbury said:

Is whatever is connected to the secondary side of the PSUs fixed?

The PSU output circuit breaker feeds fixed 400Hz distribution boards (fixed installation) and these have individual fuses for the final circuits.  Final circuits then feed out to break out "patching panels" (fixed installation) on our facility and these connect to current using equipment on the units under test (UUT).  The UUT are not fixed and get swapped out for each test and our technician teams rig and patch the equipment using mil spec connectors and the like.

gkenyon said:

I was also thinking that we don't know what these supplies do, and therefore whether they are part of the electrical installation

As above - these feed aircraft OEM parts on the UUT.  However, in order to make the connections to the UUT our operators are in proximity to the earthed metalwork of the test rig, as well as the fortuitously earthed exposed conductive parts of the UUT (fed by the ungrounded 400 Hz, 115Vrms PSU).

AJJewsbury said:

Agreed - or even separated - either for one item (see BS 7671 section 413)  or several (section 418.3).

I would struggle to agree that we have met the requirements for either section.

gkenyon said:

If you take the view that this information is necessary to safely maintain the equipment, and check it continues to be safe, the perhaps Section 6 of the H&S@W etc Act 1974 requires it to be provided. Check out 6(1A)(c).

Agreed - we will make the appropriate enquiries and seek to make rectifications as soon as possible.

Given the above, I am concluding that we should be implementing ADS to mitigate the risk of electric shock presently.

Many thanks,

Richard 

Hello,

Thank you for your replies.

gkenyon said:

ADS has been assumed ... but does the system and connected equipment use something else ... double or reinforced insulation, for example?

ADS is assumed because the 400 Hz power supply feeds multiple items of class I equipment and the exposed conductive parts of these items are not isolated from the exposed conductive parts of other circuits and also have fortuitous connections back to facility PE via the local metalwork which is connected to the MET.

AJJewsbury said:

Is whatever is connected to the secondary side of the PSUs fixed?

The PSU output circuit breaker feeds fixed 400Hz distribution boards (fixed installation) and these have individual fuses for the final circuits.  Final circuits then feed out to break out "patching panels" (fixed installation) on our facility and these connect to current using equipment on the units under test (UUT).  The UUT are not fixed and get swapped out for each test and our technician teams rig and patch the equipment using mil spec connectors and the like.

gkenyon said:

I was also thinking that we don't know what these supplies do, and therefore whether they are part of the electrical installation

As above - these feed aircraft OEM parts on the UUT.  However, in order to make the connections to the UUT our operators are in proximity to the earthed metalwork of the test rig, as well as the fortuitously earthed exposed conductive parts of the UUT (fed by the ungrounded 400 Hz, 115Vrms PSU).

AJJewsbury said:

Agreed - or even separated - either for one item (see BS 7671 section 413)  or several (section 418.3).

I would struggle to agree that we have met the requirements for either section.

gkenyon said:

If you take the view that this information is necessary to safely maintain the equipment, and check it continues to be safe, the perhaps Section 6 of the H&S@W etc Act 1974 requires it to be provided. Check out 6(1A)(c).

Agreed - we will make the appropriate enquiries and seek to make rectifications as soon as possible.

Given the above, I am concluding that we should be implementing ADS to mitigate the risk of electric shock presently.

Many thanks,

Richard