Family Handyman fixes knob-and-tube without plaster

Old-house wiring is one of those renovation problems that gets expensive fast. The wall looks fine, the plaster is worth saving, but the wiring behind it belongs to another era. That’s the gap Family Handyman’s piece is trying to close — not a whole-house rewire, but a very specific fix for a very common problem: changing an old light fixture when the original knob-and-tube setup has no electrical box. The update in their July 25, 2024 guide is basically this: you can bring that connection up to modern expectations without blowing open the wall. (familyhandyman.com) ### What exactly are they fixing? They’re fixing the old “fixture screwed to plaster, wires just emerging from the wall or ceiling” setup you find in houses built before World War I. Back then, knob-and-tube wiring was installed under older rules that did not require electrical boxes for light fixtures. That becomes a problem the minute you swap the fixture, because modern code expects those connections to live inside an approved box. (familyhandyman.com) ### Why does the plaster matter so much? Because plaster-and-lath is fragile in a very particular way. If you cut too wide or crack the “keys” — the plaster that mushrooms behind the lath — the surrounding surface can loosen and crumble. Family Handyman’s whole trick is to work just big enough for the box and no bigger. That is the real value here. It is less about fancy rewiring than controlled damage. (familyhandyman.com) ### So what’s the actual method? The guide walks through laying out the box opening, probing for the lath edges, then cutting down both sides of the center lath and removing only what is needed. After that, you partly trim the top and bottom lath so the box fits while the remaining material still supports the plaster face. In plain English — you make a precise pocket instead of a demolition zone. (familyhandyman.com) ### How does the new box stay in place? With metal support arms that slide alongside the box and bend around its edges to lock it in. That matters because the fixture now hangs from something solid and code-recognized, not from old plaster doing a job it was never meant to do. If the existing wires happen to come out beside a stud, the job is eve(familyhandyman.com) the middle of an open stud cavity. (familyhandyman.com) ### Does this mean knob-and-tube is suddenly fine? Not exactly. The article makes a narrower point: the old conductors can remain acceptable if their insulation is still intact, but the connection itself has to be enclosed in an approved box when you update the fixture. That is a repair rule, not a blanket endorsement of leaving an old system unt(familyhandyman.com) most likely to need meaningful electrical upgrades. (familyhandyman.com) ### Why is this showing up now? Because homeowners keep running into the same tradeoff — preserve original finishes or modernize the wiring. Minimal-cut techniques are attractive because full rewires in plaster houses can turn into patching, skim coating, repainting, and weeks of mess. Family Handyman has been leaning into that theme across older(familyhandyman.com)y when you repair or extend circuits. (familyhandyman.com) ### What’s the catch for DIY readers? Electricity does not forgive improvisation. Family Handyman starts with the obvious but essential step — shut off power and verify with a non-contact tester. And their separate code-violations guide is blunt that DIYers still have to follow the same NEC and local rules as pros. So this article is best read as a narrow how-to for one repair condition, not permission to freestyle old-house wiring. (familyhandyman.com) ### Bottom line? The useful idea here is simple: sometimes the smart old-house electrical fix is not “open the whole wall,” but “create one proper, supported, code-compliant transition point and leave the plaster standing.” (familyhandyman.com)