Levels & Squares

Level, plumb and square are the three things that cannot be eyeballed. An I-beam level is the jobsite standard because the shape resists twist, which is what actually throws a reading off over a long run. A magnetic edge frees both hands on conduit, strut and steel stud, and is the reason most electricians own a magnetic level rather than a plain one. Length is the real decision: a compact torpedo lives in a pouch and levels a box or a short run of pipe, a 24-inch spans most framing and panel work, and a 48-inch is what you want for a door, a rack, or anything where a short level would ride a local high spot and lie to you. A framing square handles the other axis - marking a true 90, laying out a cut, checking a corner that has to be right before anything gets fixed to it. Aluminum stays readable and does not rust in a truck. Check a level against itself by reversing it end to end; if the bubble moves, it is out.

Laser levels solve the problem a spirit level cannot: transferring a line across a room without a chalk line and two people. A cross-line laser projects level and plumb for layout of rack, conduit and fixtures; a rotary laser sweeps a full plane for grading, ceiling grid and long runs, and pairs with a detector outdoors where the beam is invisible. Self-leveling within a few degrees is standard and worth insisting on. Check any laser against a known reference before trusting it on a long span — knock a laser off a bench and it can read confidently and wrongly. Speed squares, combination squares and framing squares cover the marking side, and a digital angle finder handles the bevels that a fixed square does not.