The maximum height of a sign shall be computed by measuring the distance from normal grade to the top of the highest component of the sign or its framework.
A. 
Normal grade shall be construed to be the lower of:
(1) 
The existing grade prior to construction; or
(2) 
The newly established grade after construction, exclusive of any filling, berming, mounding or excavating solely for the purpose of locating the sign.
B. 
Where the normal grade cannot be reasonably determined as above, the normal grade shall be considered to be the lower of the following:
(1) 
The elevation of the nearest point in the crown of a public street; or
(2) 
The elevation of the principal entrance of the principal structure on the zone lot.