Upgrading Wiring in Old Lath and Plaster Homes

Upgrading Wiring in Old Lath and Plaster Homes

For some electricians, rewiring older houses is their bread and butter.  After all, there are plenty of places where knob and tube still exist and insurance companies or electrical code demand it be upgraded.  For other electricians, though, the idea of jumping into rewiring can be a compelling, if not intimidating thought.  Although it’s not a lot different from running wiring anywhere else, there are some considerations when upgrading wiring in older homes, especially those with lath and plaster.

Writing the Contract

When you’re doing a rewire in a home with lath and plaster, there is a high probability that you’re going to have to bust some of the plaster out in order to access difficult to reach spots.  After all, outside walls can be hard to fish if an attic is short or the slope is inadequate or if there’s not a good crawlspace.  Knowing this, designing a contract that protects you from responsibility from damage due to reasonable and necessary openings in the wall is vital.

Obviously, you should be doing all you can to minimize wall damage and leave enough behind that the wall can be patched easily, but a small hole saw can make quick work of lath and plaster, providing adequate access for most jobs.  If you can hide those holes under fixtures or within outlets, obviously that’s the best route to take.  The less damage, the smaller the mess – and the more likely those homeowners will invite you back.

Alternatives to Fishing Wires

In many cases, you can test the integrity of wiring to determine if it’s still properly insulated and safe to use with tools that can provide information on resistance and load.  You’ll need a visual on as much of the wiring as possible so you know if the wiring type remains adequate for the load center involved in the upgrade, but if what’s exposed in attics and crawls looks serviceable, there’s usually not a reason to actually replace all of the wiring.  That alone can minimize the necessary damage dramatically.

Check your local codes to make sure you know what your responsibility is in this situation, but to really minimize damage during an upgrade, starting with reusing old wiring is paramount.  Homeowners may need to be schooled in what to expect from an upgrade, including the real possibility that their home will not be wired in the same way that a new home would be, since the way wiring was installed 50 years ago has changed substantially.

There’s nothing wrong with having all the outlets in a couple of rooms on the same breaker (as long as it complies with code), but if they expect that each room will be wired individually and on a breaker clearly labeled “living room”, they may be disappointed when you explain otherwise.  There’s a balance to be struck between plaster damage and wiring style.

When You Must Fish

Sometimes, you have to fish, no matter what, just do so carefully.  It may be difficult to secure wiring to old studs that have hardened, but you can’t simply leave them dangling in a lot of municipalities.  You’ll have to think on your feet and probably get an endoscope involved for the trickiest spots.  Again, make sure your client understands the reality of upgrading an older home’s wiring and the limitations of replacing wires and reconfiguring circuits when the walls are closed.

Upgrading the wiring in an older house can be a challenge, so make sure to figure in plenty of extra time for any unexpected surprises.  Having a skilled plasterer who can repair any necessary damage caused by your work will also go a long way to keeping homeowners happy.

What are your top tips for upgrading the wiring in older homes?   Let’s talk wiring in the comments!

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