Do I need a sub panel?
One of the more common questions people ask. The main thing to look at in your panel is if you have any more “spaces”. There is often a metal (or if the metal has been removed, then a plastic) space that clearly looks like it can be taken out where a breaker would go. If you have more spaces then it is a very good chance you won’t need a sub panel. Below is a photo of a panel that looks like it has room, but there are clear markers on the external of the panel saying there is no more room. Therefore, even though it looks like there may be room, especially if these stickers had been removed or fell off at some point, there is not. These panels are not common and generally if it looks like there is room, then there is. To date I have only seen this issue with Federal Pioneer panels and Cutler Hammer panels.
No more room? There is still no certainty that you need a sub panel. There are regular breakers and space saver breakers. Space saver breakers come in every “push in” style of breaker and usually range from single 15 amp breakers to 2 pole 40 or 50 amp breaker (depending on the brand). So if there are regular sized breakers in your panel, then there is still room to squeeze in some space saver breakers for more room.
No more room and only have space saver breakers? You likely need a sub panel. There is still a chance that once a person who is comfortable or qualified to take the panel cover off may find a spare breaker or two, but this is rare if the panel is this full. There are also some instances in older panels that space saver breakers are not suitable. There are a variety of other issues that may appear once the panel cover is off, but they are not the norm and are usually case by case.
Common mistake: sub panels DO NOT give you more power, they only give you more space for breakers. More power is only obtained by upgrading the service.