Often not without rearranging, adding a subpanel, replacing the panel, or using a listed load-side solution — and none of those steps skips a load calculation. Tandem (skinny, twin, or “cheater”) breakers put two circuits in one slot. A panel that is already full of them usually has no unused space for a two-pole EV breaker, and some of those tandems may not even be listed for the positions they occupy. Filling every slot with tandems was treated as a warning sign, not as proof of capacity, in the r/askanelectrician thread about a 60-amp charger on a 100-amp service.
Three questions have to be answered separately:
- Listing. The panel label states which positions accept tandem breakers. A full row of tandems is not automatically legal.
- Physical space. A 240-volt EV circuit needs two adjacent pole spaces (or a listed two-pole tandem arrangement, which is uncommon for this use). A subpanel or a panel replacement may be what creates those spaces.
- Service capacity. Even if you free two spaces, the 100-amp (or other) main still has to carry the existing load plus the charger. See the open-spaces-versus-capacity page.
Do not start by swapping in more tandems to “make room.” Have a licensed electrician inspect the panel, the label, and the load, and use the calculator for the capacity half of the question.
This is not a permit calculation, a utility approval, or a substitute for a licensed electrician, HVAC contractor, or the authority having jurisdiction. Panel Headroom is an independent educational site. It is not a utility, a certification body, or a contractor. Electrical and generator work that is done incorrectly can cause fire, shock, or carbon monoxide poisoning. Use the adopted electrical code and manufacturer instructions; pull permits where required.