ECN Forum Forums General Topics of the Trade General Discussion Area Service change, do I need to add Arc Supression?

Strictly speaking, you will not have to install AFCI's until the 2002 NEC(unless locla codes require them now). However, since you are going to be doing an upgrade, why not install the devices for the added margin of safety? Table 310-15(b)(6) permits #4 copper for 100 amp residential services.