Hello, my girlfiend and I recently made an offer on a 2 bedroom 1 bathroom house and they excepted, this house is really old and we found out with home inspection it has the old type knob and tube wiring and is not grounded. we would want to put in the new style electrical wiring and update it. . does anyone know what this costs to do this?

The cost depends on the size of the house, number of floors, and also, if it is knob and tube there is probably the old style fuse box, most likely 60 amp service. In pennsylvania, you cannot insure a house with knob and tube, and the 60 amp must be upgraded to 100 amp with circuit breakers. This job will run into the thousands, everything needs to be replaced, circuit box, meter, wires, plugs, light switches, everything, including most of the fixtures, as they are probably as old as the wires.

As an agent, I would first get an estimate, from the service to full wire replacement, and either deduct that entire cost from the offered price, or give the owner the option of replacing it at their expense. Don't know where you are from, but in this area, the housing market is very slow, there are many, many houses on the market for more than nine months, without any offers. Do not offer the asking price, get the work done by the owner, and check with your insurance providers. If the wiring is that old, I would be wondering about the foundation, roof, plumbing, furnace, and other things in connection with this house. There have to be a dozen more homes within a one mile radius of that home that need less work.

I just noticed you have already made an offer. How could you make an offer without knowing this? Was there a seller's disclosure? If this was not noted, then your can back away from that offer. Do you have an agent? If not, get one, or you run into this kind of problem again.

Remember, the seller pays the agent fees. Get someone who knows the laws, rules, pitfalls, etc.

Later
Albert

I re-wired my old knob&tube 60 amp service house about 14 years ago. Aside from a load center, the materials are not that expensive. Under $2000 then as I recall. The main cost is the labor. Inspections alone will run hundreds of dollars in most locales. You will usually find in the old houses that pulling cable is not straight forward, they used to run 2x4s parallel to the floor about half way up the wall. You pretty much have to start from scratch but with the disadvantage of having all the walls, insulation etc in place. The original installation is done to the accessible frame--so much more labor intensive than a new house wiring. Also it is extremely unlikely that you have enough outlets, GFCI's etc. to satisfy code (it will not pass inspection unless it meets modern standards), so it is not just duplicating the old wiring setup in romex, but putting in a lot of new stuff. If you are not handy with tools or confident about your ability to handle electrical work safely, you have a MAJOR expense and if you are, you have a major project. Get a couple of electricians to give you a bid. Even in a recession with a lot of guys hungry for work, I think you will be unpleasantly surprised.

I just got a quote to rewire a complete 900sf wooden bungalow. It's going to be around $5k.
But, I already had the same contractor install a 200amp panel in anticipation of the project. Add another k.

I hope you enjoy your new old house. I like old buildings... and am usually disappointed with the workmanship I see in new construction.

If your region has a legacy of old houses chances are you can find a electrician that specializes in rewires or at least has ample experience with the job.

Get a bid. Most electricians will happily come out and visit and get back to you with a bid.

We had prepared a blueprint with all the electrical features to help make the process a bit easier to keep track of.

It doesn't have to be to scale as much as it needs to itemize the outlets and features.

best regards,
mike

I am an electrician..... though now days I do mostly security related work....alarms, cameras, etc....

I did quite a bit of service changing and rewiring. Depending on the size of the house, the project will easily cost $4k to whatever. A service change alone can be $2k easily.

I hope the walls will be torn out (opened up) so the new wiring can go in almost like a new job. That would involve insulation, sheetrock, paint, and trim...... adding to the cost. 

It is possible to totally rewire a house with walls intact.... but that will generally add 15% to 25% to the cost due to increased labor costs.  I was one of the few electricians in this county that would actually do old work rehabs..... it's dirty, but at times fun. I found all sorts of antique bottles and stuff in the attics and under the houses.....

If your offer was low and the house has potential...... you can pull this off and have a nice house when it's all done. I would recommend learning how to do a few things yourself like tile and paint, and maybe basic door trim and stuff like that. Let the pro's handle the plumbing and electrical, heat & air, and the critical stuff that needs a professional to install it. I did all the electrical, most of the plumbing, and 90% of all the other work (tile, paint, trim, cabinets, mirrors, ) on my addition a few years back. I had the masonary, framing, insulation, HVAC and sheetrock done for me.  I estimated that I saved ...easily $30k on labor and material markup.  It also allowed me to upgrade my fixtures with the money saved. The home improvement stores in your area hold "classes" every Saturday morning for do-it-yourselfers to get the basics..... be there and learn.... it will save you money ...IF.... you do the job right.

This thread got me to thinking - the house I live in has a mish-mosh of knob and tube, romex and bx and cloth covered wiring, but the incoming service and load center was redone to a breaker box with 100 amp service by the previous owners (we've been in the house 26 year this Thanksgiving) so it's been a while. Got grandfathered in on the wiring but I don't think so if/when we ever go to sell. There's no knob & tube to the breaker box.

Interesting thing I found out back in 2007 when I had an electrician in to take care of a couple of problems (they had to re-do the grounding of the incoming service amongst other things) was that even to just replace an existing duplex outlet I needed a licensed electrician to come in and make the change. This is in NJ. Don't know if it's part of the NEC or just Joisey beign weird.

Yep to all of the above. Lathe and Plaster walls? <--( More expense to remove and replace ) If it's an old house it probavly needs to be re-insulated anyway. If it has an attic that is accessible with no floor, you could probably get by with stripping the walls (cutting strips out where you need electrical put in is just a major PITA), redoing the electrical and other things I'm sure you'll find, re-insulating and re-covering the walls. But make no mistake, the house will be a war zone for some time.
I don't know the electrical codes in your area, but you might check on adding a new service, feeding the old one and the knob and tube with it, and adding grounded plugs and GFCI's from the new service. ( Much lessdestruction ) That's a long shot, it's usually not allowed. A lot of old timers say knob and tube is a good system. You should also check to see if you are required to upgrade the electrical upon buying the house because the grandfather clause may have expired in your area. A lot of headaches to check on.

I don't think there is anything inherently wrong with knob and tube. In my circumstance it's the condition of the 50 year old cloth covered two conductor wire that's motivated me to have everything upgraded.

best,
mike

Interesting thing I found out back in 2007 when I had an electrician in to take care of a couple of problems (they had to re-do the grounding of the incoming service amongst other things) was that even to just replace an existing duplex outlet I needed a licensed electrician to come in and make the change. This is in NJ. Don't know if it's part of the NEC or just Joisey beign weird.


No.... that is part of the NEC and a professional electrician will do the job right. You can't simply pop in a new duplex outlet on an ungrounded circuit. The code allows a GFCI but...... a good solid  ground is the best and safest way to go.  Jersey is weird.... but in this case, they are complying with the NEC. A solid ground "anchors" the 2 "legs" to a common reference voltage.... near zero at ground. This keeps the legs at 120v from ground and 240v between them. Loose the ground and the voltage between the legs stays at 240v...however the legs reference to ground depends on the load being used..... which means one leg could be at 80v to ground and the other leg will be at 160v to ground...... just imagine your DAW being on either of those legs with that voltage being that far off...... stuff will burn up. More than once I have been called to a house with these voltages and complaints that their appliances and light bulbs are burning out, and re-working the ground connection solves the problems. A loose neutral will also allow this to happen.

Knob & tube is theoretically a very safe wiring method...due to the seperation of the conductors.  However, the insulation tends to dry out and crumble off, creating a shock hazard, and of course, it's an ungrounded wiring method.  I would replace all K&T, as well as BX, and non-grounded Romex.

In addition, during certain times in the past, some electricians thought it was a good idea to wire houses with aluminum romex. It was cheaper than copper, and copper was in short suppply at the time and very expensive.....It was permitted by code at the time, and some of this wiring still exists in homes today. I would not sleep in a house wired with this stuff. It would have to come out and copper installed.

Yeah... good points on the grandfathering issue too. Sometimes, depending on the jurisdiction... inspectors will require upgrades. And you must complete it before they will let you move in and turn the juice on.

Knob & tube is theoretically a very safe wiring method...due to the seperation of the conductors

That's arguable. Although the physical separation makes it harder to accidentally short the two, it also increases the time it takes for a short to trigger a circuit breaker due to the higher inductive reactance. Safety concerns are the reason ground wires are required to run in the same conduit as the other wires in industrial wiring. A millisecond's difference in the response time of a circuit breaker can be the difference between "oh sh*t!" and death.

k&t wiring also prevents the two conductors from having any common mode noise rejection. If I were to build a studio in a structure wired this way I would run a dedicated circuit from the service entrance to the studio. If that wasn't possible, as in a rental, I'd install an isolation transformer in the studio.