5 Jan 91
2358 mA or approximately 2.4 amp
which agrees well with the current requirement test
data provided in item 12 of paragraph 2-2a.
Select an anode and calculate the number of anodes
required (N) to meet the design life requirements. Two
sizes are selected for trial calculations using
2.8 amp (Current requirement from item
12 of paragraph 2-2a)
Current rating per anode, varies de-
pending on anode size from table 3-3.
Several different size anodes could be chosen.
Experience has shown that for this type of groundbed,
60-in. long anode packages are desirable.
For a 3-in. by 60-in. packaged canisters with a 1/8-in.
by 48-in. ceramic anode rod, IA = 1.2 amp/anode (from
table 3-3 for 15-year design life).
= 2.33; use 3 anodes.
For a 3-in. by 60-in. packaged canister with a 1/4-in.
by 48-in. ceramic anode rod, IA = 2.4 amp/anode (from
table 3-3 for a 15-year design life).
= 1.17; use 2 anodes.
Calculate the resistance of a single anode-to-earth (RA)
from equation 1-6:
where groundbed is desired from item 1
of paragraph 2-2a)