Two 110VAC Supply in One Multicore Cable

Certified? is this a hazardous area distribution panel?

Why two sources? Is this for current sharing because the conductors are too small or a source-transfer application between two different independent supplies?

Multicore cables are generally for control logic, not power. What standards are you working too, is this an American installation or somewhere else?

Please provide more information.

Hi Jack,

The panel is hazardous area certified for explosion proof. We need two source supplied by two UPS incase one fails there is no down time. It is not in America but we are following American standards, the panel is supplied by US company.

I have never done this before as well and am not sure if it can be done. However, if it cannot be done, could you please explain why it cannot be done? I need to convince the people who are trying to go this path to not do it. Thank you.

Milan

<...two UPS incase one fails...> Are these cables to be supplied from two fuses, in case one blows, then?

<...explosion proof...no down time....> Then the panel has to be functioning correctly before it is installed and energised, for no testing or modification will be possible once energised. That is the drawback with <...explosion proof...> equipment over other methods of achieving safety of electrical equipment in hazardous atmospheres. Incidentally, it will prove possible to install it only using non-sparking hand tools, in that case.

<...have never done this before...> If no training has been completed, then either carry out training beforehand or delegate the task to someone who has been trained. This is a specialised field and not one for the uninitiated.

Other things of note:

• It is not possible to have humans inside ATEX hazardous area zone 1, as the facility would face enforcement and/or prosecution for non-compliance on health & safety grounds. So the panel goes either into ATEX hazardous area zone 2 or the safe area; if going into the safe area then a hazardous-area-certified unit is not required, and best dispensed with.
• If the ATEX hazardous area zones are large, then the facility has a major materials containment problem that requires addressing immediately on health & safety, environmental and economic grounds.

I cannot see any issue with using a multicore cable as long as it is appropriate for the power transmission, which means voltage rated, current rated, and following any other necesary standards for this application.

The only problem you may have could be that multicore cables have worse heat dissipation, so compared with single core cables, you may need higher cross section, incurring in more expensive cables and maybe some dificulties to get the multicore cable trough the core.

If it does not fit, you can use military rated cables, aa long as you can afford it!

Thanks guys. My management has agreed not to use multicore cable for the UPS supply and proceed with drilling holes and recertification as required by our supplier.

Who gets stuck paying for that?

Above my pay grade. LOL

Good. This is the best solution in this case given the information presented.

US codes not my space, but if that was for underground coal mining in Aus, would need re-cert for any modification to the level of seal. Any new hole = re-cert.

Re-cert testing of a modified unit usually cost more than obtaining an alternative certified unit that would suit.

Congrats for taking the conservative approach and getting the testing done.

Interesting. Congrats on the decision to run two supplies separately, and re-certify the enclosure.

Not sure what you mean by "certification", but if this is a UL 508A inspected panel, the new holes, if filled by a gland with correct rating for the area, are allowed. Our in plant shop built UL 508A panels are often inspected before the holes are even made. It is also common to get UL 508A inspected panels for our process skids, built by another shop of the end customer's choosing, not our own in plant shop, with no holes. We add them as needed to run the skid wiring. UL 508A still applies to the panel.

http://www.cooperindustries.com/content/dam/public/crousehinds/resources/pdfs/other-pdfs/crouse-hinds-codedigest2014.pdf