# Inverter retention calculation options

Inverter weight: 20kg estimate

NEDRA section 8.1: Mounts must withstand: 8 x weight horizontally = 160kg = 353 lb 4 x weight vertically = 80kg = 176.4 lb

Using NEDRA table data:

IF use 3/8" bolts (10mm closest metric equivalent) THEN each bolt takes 60.4 lb THEREFORE 353 / 60.4 = 6 bolts

IF use 7/16" bolts (works out to 11.13mm, 11.50mm closest metric equivalent) THEN each bolt takes 82.6 lb THEREFORE 353 / 82.6 = 4.3 bolts. Check to see if 4 bolts is sufficient to meet requirement: A 7/16" bolt has an area of: 97.3mm2 A 11.5mm bolt has an area of: 103.8mm2, or 6.7% larger Total area required: 97.3mm2 x 4.3 = 418.4mm2. Area of 4 x 11.5mm bolts: 103.8mm2 x 4 = 415.2mm2 Therefore does not meet requirements, short by 3.2mm2 of bolt c.s.a.

Therefore 4 x 12mm bolts would meet requirement well.