"ampacity" means "capacity in amperes" or more literally "ampere capacity." You could say current capacity too but it takes longer. Ampacity is the language used in the electrical code.
"amp" also seems to be more common to write than "A" for electricians. Remember that the SI standardization of unit abbreviations is actually a pretty modern thing, so lots of fields existed before unit abbreviations were standardized and continue to use existing practices.
"amp" also seems to be more common to write than "A" for electricians. Remember that the SI standardization of unit abbreviations is actually a pretty modern thing, so lots of fields existed before unit abbreviations were standardized and continue to use existing practices.