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Old-House Online » Old-House Tips, Restoration Stories, & More » Repairs & How To » 10 Tips for Rewiring an Old House

10 Tips for Rewiring an Old House

What you need to know to get an old house rewired properly, with minimal damage to the building. By Tony Seideman

    Old houses often need updates to electrical systems; the author’s 1903 home was no exception. Follow these tips to get it done without causing undue—or irreparable—damage to your building.

    Old houses often need updates to electrical systems; the author’s 1903 home was no exception. Follow these tips to get it done without causing undue—or irreparable—damage to your building. (Photo: Jon Crispin)

    Computers, blenders, TVs, even refrigerators—none of these existed when many historic homes were built and first wired. So upgrading electrical systems is an essential task for a lot of old houses. Yet efforts to update electrical systems can often result in damage to historic buildings.

    Conversations with top electricians have provided us with a a list of steps to take in order to make rewiring proceed more smoothly, with fewer holes punched in the walls, floors, and ceilings—or, heaven forbid, a structural beam.

    Steps to Safely Rewiring Your House

    1. Do an “electrical inventory,” creating a list of all the devices you’ll be using in the house, and where. Your electrical system needs to match your needs; figuring out where and how you’ll be using power makes it easier to frame the parameters of the job.

    2. Check out local codes and pull permits. Codes set standards for everything from how many outlets you’ll put in each room to what kind of wire you’ll be using. Failing to get permits can result in having to pull out finished work.

    3. Decide whether you want to run just electrical, or data, fire, and security as well. Modern wiring doesn’t just carry electricity, and wireless systems are getting increasingly cheaper and more sophisticated.

    4. Use your list to create a detailed plan of action. Once you’ve done your initial homework, sit down and create a punch list that focuses on what you want done and when you want it completed; the list should be the basis of your relationship with your electrician.

    Breaker panels with a jumble of old wires (top) need to be checked carefully by an electrician for intact coatings, burn marks or signs of arcing damage, and solid connections.

    Breaker panels with a jumble of old wires (top) need to be checked carefully by an electrician for intact coatings, burn marks or signs of arcing damage, and solid connections. An updated main panel box (bottom). (Photos: Jon Roberts/Courtesy of Perfect Electric Services, Inc.)

    5. Watch for existing infrastructure.Part of avoiding damage is making sure nobody punches holes in plumbing or existing wiring. This kind of awareness needs to be a top priority in any rewiring job. “Ask twice, drill once”—one historic electrician’s credo—are words to live by.

    6. Always put things in writing, but leave flexibility. Surprises invariably show up, especially when you’re digging deep into a building’s structure.

    7. Find an electrician who knows and understands older buildings. Working in older buildings is a complex, demanding, and difficult process.

    8. Make demolition and reconstruction an integral part of the job. If dealing with the damage done by rewiring isn’t at or near the top of your list, you’re asking for trouble. Make cleanup and restoration as important as the wiring itself.

    9. Aim for “home runs” for key areas and appliances—these are when a wire runs directly from a circuit breaker to an outlet, with no other devices on that breaker. That can reduce loads on the power system and keep popped breakers to a minimum. Additionally, it’s important to keep track of which areas feed to which breakers where more than one outlet is involved. Creating a “balanced” system will make life easier as your load expands and you put new wiring to use.

    10. Integrate switches and plates into the historic look and feel of the house. Numerous companies offer hardware that matches the appearance and the feel of almost any era, while providing a far greater margin of safety than older equipment does.

    Modern Demands

    New wiring systems often can be run near the old—as in this vintage house that’s been successfully rewired, with a new box placed near now-defunct ceramic knobs on the basement ceiling.

    New wiring systems often can be run near the old—as in this vintage house that’s been successfully rewired, with a new box placed near now-defunct ceramic knobs on the basement ceiling. (Photo: Peter Means)

    The demands of modern technology can exacerbate the situation, and they’re at risk of doing so all the time. Older houses were built at a time when 60 amps was considered plenty of electricity for a single residence. By contrast, most new homes are built with 150- or 200-amp service, but 100 amps was the standard for many years—and most experts agree that anything less than 100 amps is unlikely to meet the electrical needs of a contemporary household.

    I can attest to that—my house has 100 amps, and it definitely isn’t enough. The service is split between a main panel in the basement and a sub-panel on the third floor. The panel on the basement is so fully loaded that we’ll have to do an upgrade when it comes time to finish the kitchen. And our electrical work to date has left uneven holes punched in our walls and ceilings, which have proved difficult to repair.

    Prevention is Key

    Creating a clean cut via a hole saw or careful work will make it easier to make walls or ceilings whole again. Uneven access holes, like this one punched in the author’s house, prove difficult to patch.Clean cut hole

    Creating a clean cut via a hole saw or careful work (bottom) will make it easier to make walls or ceilings whole again. Uneven access holes, like this one punched in the author’s house (top), prove difficult to patch. (Photos: Tony Seideman/Peter Means)

    First and foremost, it’s critical to understand that you’re dealing with an older building—and if keeping the structure of that building relatively intact is your top priority, you need to say so up front. Chances are you may have to pay a little extra to protect your building, but a few preventive dollars and hours can save big sums spent on restoring battered walls and weakened structures.

    Make sure specialists each focus on their areas of expertise. “Try to never let the plumber or electrician cut holes, especially in an historic building,” historic architect Robert Gabalski told us. “When you’re walking an electrician through a building, require in the specs very specific ways to cut and patch, or make sure the general contractor does it for them,” he advises.

    One of the biggest mistakes many restorers make is to try to replace every piece of old wiring in the system, says Michael Hedrick of Historic Electric Preservation in Fredericksburg, Virginia. “Most efforts tend to be heavy-handed and replace more than what is truly necessary to an older system. Many parts of an older wiring system, if they have been undisturbed, are still quite usable and reasonably safe,” he says. “Bottom line, after inspection by a competent and qualified electrician, leave much of what you find in place and working. There are many houses with electrical systems from the 1920s still delivering power in a safe and efficient manner.”

    Published in: Old-House Journal February/March 2011

    { 17 comments… read them below or add one }

    Karan Andrea January 3, 2011 at 5:35 pm

    Last year I bought a 1924 Four-Square. The electrical system was a nightmare combination of knob and tube and romex. There were so many j-boxes you couldn’t trace a single circuit out of the basement. I hired an electrician to bring a brand new 200-amp service in, and decommission the electric in the entire house. From there, my dad began rewiring it.
    We put a plan together of what I would need in what rooms, being overly generous in the kitchen and bathroom. For example, my bathroom has two 20-amp GFI circuits – one with a single outlet and the other with two outlets. I also have two other outlets in that room. Why? Why not? Yes, it’s overkill, but at the same time, my lights will never dim when I fire up my hairdryer. And if I needed to run a space heater in that room for some reason, I could still run that hairdryer and not pop the breaker.
    The bedrooms got at least two outlets on every wall. Not because I need them all, but because it’s nicer to lean down and plug something in rather than go hunting for an extension cord to place a lamp where you really need it.
    We were lucky. My dad was able to access all the existing fixtures and add center lights in each room with minimal damage to walls and ceilings. The first floor runs were done from the basement. Since we were going to redo the kitchen (first floor) and bathroom (second floor), and they are stacked on top of each other, we gutted them to the studs and used that wall to make our runs from the panel in the basement to the upstairs rooms.
    Our luck continued on the second floor since most of the outlets were already in the baseboards, and there was no lath and plaster behind the baseboards anyway. Once you pulled them off, you had full access to the studs, etc. So we simply added the extra outlets as needed. Putting center lights in all the rooms, and lights in the closets was a different thing altogether. Dad had to cut up much of the attic floor to make that happen, but given our options, that was the least destructive. It was better than ripping into walls and ceilings.
    In the end, I have a house with 100% updated electrical wiring that should last my lifetime without being outmoded unless we start running on dilithium crystals! Another benefit is that once all the breakers are labeled, I will know exactly where everything is in that box – a big plus if something goes haywire, or if you have to turn off the power to a certain room or outlet.
    While we had the baseboards off upstairs, we also had the telephone and cable TV runs done so that those are in the walls as well.
    The electrician we used to install the new service probably thinks we’re nuts, but he was more than willing to review our work and advise on code, etc. I told him that I wanted my house to meet code absolutely, but that we wanted to do the work ourselves. I would hate to see the bill if I had to pay someone to do what my dad did!
    So my opinion? Replace everything you can while you can. There will never be a better time, and you do not want your house to burn to the ground because you updated all the aesthetic stuff and forgot the mechanicals. It is tedious work, and it takes what seems like forever, but if you want forever in your old house, DO IT.

    Marilyn January 4, 2011 at 6:11 pm

    As one of those homeowners who still has knob and tube wiring working pretty well in my old house I would like to see an article addressing the hows and why-nots of insulating around this old wiring. I always read you should not do it but the why-not is not addressed. If the old insulated wire is in good shape what is the reasoning? Has anyone devised a way to insulate without touching the wires? Is anything touching the wires bad? Why? Do you slide foam board insulation in behind it?

    My house has a brick first storey and framed second storey and attic. There are some walls that I am repairing and may as well insulate while the plaster is off. Also, I may want to insulate the attic at some point, and there is knob and tube in very good condition there.

    I don’t want to ask an electrician these questions because they would have a vested interest in the answers.

    Fred Allen January 6, 2011 at 3:55 pm

    ask your electrical inspector about code requirements or get the code book look it up.

    Fred Allen January 6, 2011 at 4:35 pm

    Article 324 concealed knob and tube wiring NEC 1999 p70-148
    Article 324-4 uses NOT permited
    “insulating material that envelops conductors.”
    ——————————————————–
    why not ? this can overheat.

    Frank March 21, 2011 at 8:59 pm

    We really enjoy your magazine. On the Feb-March 2011 issue, on Page 42, the picture where it shows the wire on top of the copper pipe, it seems that the wire and the copper pipe should not be touching because that would wear a hole in the wiring.

    Dr. William Sc0tt Wallace December 20, 2011 at 5:28 pm

    The U.S. Department of Energy has a web page that discusses why you do not want to use knob and tube wiring and do blown in insulation, since the possibility of rodent or other animal damage, or aging may have destroyed the original wire insulation, thus leaving the copper wires bare, and if they were to become hot, they could set fire to any blown in or other insulation.

    Anaheim Wiring January 3, 2012 at 6:51 pm

    When you are planning to rewiring your home always consider an electrician that can perform the task properly. This is your way of keeping your home and property safety.

    donna amaral January 17, 2012 at 1:32 pm

    i rewired my cellar is it necessary to rewire the wires in your walls? i did all the outlets that were loose! and put it new light fixtures my house was built in 1926

    Andrew W March 7, 2012 at 11:40 am

    I am looking at just grounding all the outlets in a 1920 house wiring was updated by the looks of things in 1950 but none of the outlets are grounded i was planning to run 1 grounding wire to each room and ground that to each box but in doing this since the current wire is just the fabric two piece style should i just update all the wiring to romex or bmx since i would need to fish through a first and second floor from the basement since there is no crawlspace. or should i go the route of just keep open ground and putting in all gfci outlets. to protect the individual rather than the electronics

    Pinto August 14, 2012 at 1:48 pm

    @Marilyn: I’ve always heard that knob-and-tube wiring uses the airspace in the wall to dissipate heat. Insulation will block that heat transfer and make the wires much more prone to overheating.

    dennis martin November 9, 2012 at 10:44 pm

    K&T wiring will overheat and sometimes catch fire when covered with insulation, another problem is a chemical on cellulose loose fill insulation for densepacking walls / blowing attics will eat the old sheathing off it and make it more likely to burn, best to replace all the wiring @ once

    Ed Ferris November 19, 2012 at 1:25 pm

    One big hazard in 1920′s wiring is BX cable. The rubber insulation will be flaking off by now and that leaves you with bare conductors in a grounded conduit. The fix is to replace the old wires with modern THHN ones. Pulling them through the old conduit is not difficult.
    I have never seen an electrical box cut into plaster that I would feel safe in using. Breaking the strip lath leaves the box without any real support.

    Holly James March 8, 2013 at 4:00 pm

    Thanks for posting this. My husband and I just moved into an older home and we are looking into hiring electrical contractors in Victoria to help us upgrade. These are great tips but we have no idea about anything that has to do with electrical things. Thanks again! http://www.emeryelectric.com/services_overview.html

    cindy kurk April 14, 2013 at 11:23 am

    We have purchased an 1834 greek revival that has been sealed for 70 years. It never had outlets cut in walls or floors. There are only a few wall lights.This property is in process of going on the national register.How do you wire it without ruining 2 foot deep baseboards or hand split lath?

    Moss Hill Lill June 5, 2014 at 11:07 am

    Th e2 most important reasons to replace the old wiring in my mind are people protection and property protection. FIRE!! The old wiring does not have grounds and the metal clad wire which is grounded through the jacket is sketchy at best. And the insulation can become brittle after 40 or 50 years, yes? And forget about changing out a fixture where some ding dong lamped it with 75 or 100 watt bulbs. The insulation is going to fall apart as you move the wires.

    Dawn July 8, 2014 at 3:07 am

    I read the posting by Karan and it sounds as though this person has the same dilemma I have. However, I have had 3 electrical contractors in our house before we bought it since it is all knob and tube minus the kitchen –which is updated supposedly..but I believe it is shoddy work. Anyway, one electrician arrived without anything and told me he was going to run furring strips up my wall, needed to tear up my hard wood floors on the second floor to run wiring, and basically thought I was some dumb female home owner. Needless to say, he never received a call back, especially at the price he quoted of 28 grand without asking me what I wanted, measuring, or anything that I would expect from a professional contractor. I then had another contractor come in and tell me that I had to gut my entire house before he would do the electrical but then quoted 6 grand. Another contractor seemed pretty good or at least appeared to know what he was doing and we were going to hire him but he never returned any of my phone calls. So, now I am stuck with needing to do the electrical and now no one in my area will touch old wiring! I am to the point to where I want to do it myself and then have an electrical engineer come in and inspect, but I am not too sure on that subject. We want to remodel the entire house and replace the plaster since it is the old horse hair plaster and crumbles when a small hole is poked into it when moving furniture or kids horseplaying. Is there any way to update a floor at a time that has knob and tube or does the entire house need to be done at one time?

    Jennie October 7, 2014 at 9:50 am

    This article was big help for me, when I had to rewire whole my house on my own.
    https://www.localunitedservices.com/
    Thank you!

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