Bearings can be taken from brickwork, blockwork, steel beam flanges or shelf angle and concrete.
The nominal bearing for the conventional range of designs are:
To accommodate service voids and column notches, the hollowcore can be preformed to individual requirements. Large opening may require steel trimming supports.
It is recommended that holes of less than 100mm diameter are drilled on site, on the centreline of cores.
A number of ceiling finishing options are recommended for hollowcore units:
Drilling SHOULD NOT penetrate unit reinforcement
Legend: 
= NO DRILLING
The fitting of down-lights into hollowcore slabs is fast becoming the preferred lighting solution thanks to the increasing use of precast slabs and improved lighting technology, which have led to smaller lights and enhanced performance.
Costs are also lower as wiring and single light transformers can be installed the day after installation. The traditional method involves fitting larger light boxes, which are now more expensive than coring costs, and placing conduits before concrete is poured. Furthermore wiring can only begin once shuttering and scaffolding have been removed some two to three weeks later.
Down-light coring is simple and accurate and far more economical than the installation of light boxes. Larger holes can be factory formed subject to a maximum diameter of 560mm and any edge chipping can be easily repaired with Rhinolite or a similar material. Modern lighting equipment is a lot more compact, allowing for ancillary equipment as well as wire to be stored in slab cores.
