Hi All,

Hopefully a quick one to answer.

Can the grouping factors detailed in table 4C3 be used for ducts installed in a stacked formation, as long as the separation distances are adhered to as this is not shown in BS7671?

The scenario I am looking at is if we had 6 ducts at 250mm apart, instead of all been in a row, could we have 2 rows of three if the 250mm was also applied from the top of the lower tier to the bottom of the upper tier as well as in between for each row.  

ERA69-30 Part 3 does have de-rating factors for a tier formation installation but I was wondering if the above was also acceptable.

Regards

Mark