We get a lot of questions from customers who are looking to replace their BX wiring. We thought it would be helpful to have all the questions and answers in one place. If there are any questions you would like addressed not on this list, please let us know.
Q: I’m having my house insulated, do I need to remove my BX wiring?
A: NO. BX wiring can touch insulation without any issue. This is one BIG difference between BX wiring and knob and tube wiring.
Q: Should I replace the BX wiring in my house while replacing the knob and tube?
A: BX wiring is the second generation of wiring used in homes. It does not have the same insulation or insurance issues that knob and tube wiring does. It is also quite old, being used from the early 1900’s up till the 1940’s. In some homes it may be 100 years old at this point. Lots of homes built between 1905 and 1932 have a combination of knob and tube and BX wiring.
Most customers who are replacing their knob and tube wiring for insulation will leave the BX wiring in place. We often joke that we are saving some work for later, that we will be going back through all these homes again in 10 years to replace the BX wiring.
If your house has both, we are happy to give a separate estimate to replace the BX wiring so you can decide if it’s worth it. It will certainly be cheaper to do it now, then years from now!
Q: What are the issues with BX wiring?
A: It’s an ungrounded wiring style. Although the exterior of the wire is metal and CAN act as a ground, it was never meant to be a ground, it was intended to protect the wire from damage.
I want to clarify what I meant by the metal exterior “can act as a ground” – BX wiring will run from box to box (outlet, switch, light etc.) creating a circuit. All these boxes will be metal and for the ground path to be “good”, the connections at every one of these boxes must be tight. The issue here is if one or more connection is loose the ground becomes ineffective. Where this can become quite dangerous is if you have a short to ground, and the ground is weak, the circuit breaker will NOT TRIP, meaning the metal exterior of the wire is now LIVE, carrying current back to the panel.
Since it is ungrounded, new wiring cannot be extended off of BX wiring. For example, if you want to add a new outlet in a room and there is a nearby BX outlet, this outlet cannot be used to power the new outlet.
Three prong outlets cannot be installed on BX wiring, unless a GFCI outlet is used. Even with the GFCI, there is still no true ground present.
It has a cloth insulation which can break down to expose bare copper. This is particularly an issue in lights where heat from light bulbs has baked the wiring for years.
It’s old!! At the time or writing this (2021) it is likely 100 years old, or more. Expecting this wiring to last with the electricity demands of today is not realistic.
Q: Will you gut my walls to replace the BX wiring?
A: NO, walls will not need to be gutted. If you are talking with an electrician saying your walls will be gutted, look elsewhere!
Q: If you are not gutting the walls, how do you replace the BX wiring?
A: Some small holes will need to be created to fish the new wiring around. Electricians who are experienced doing this kind of work will only make the holes in necessary locations to minimize overall damage to the house. Most holes are around 1” in size and we rough patch them.
A lot more information can be found here about holes needed and techniques used – https://www.kuhlmanelectricalservices.com/rewiring-techniques/
Q: Do you need to remove all the BX wiring after rewiring is complete?
A: All visible BX wiring will need to be removed in spaces like unfinished basements and attics. Basically, anywhere the BX wiring is visible it must be completely removed. In walls and ceilings where it’s concealed, it does not need to be removed, just deactivated.
Q: Can I live in the house while the work is being done?
A: Yes absolutely. I would say 95% of our customers are living in their home while we are doing the BX wiring replacement. While working our electricians use plastic coverings and vacuums and mitigate all the dust created.
Q: Does my power need to be turned off during installation?
A: Only the BX circuits we are working on for safety. The other non-BX circuits we are not touching will be left on.
Q: Do I need to add outlets around my house to bring it up to current code while having the BX wiring replaced?
A: No, you don’t. At minimum it needs to be put back how it was. For example, if the room with BX wiring only has 1 outlet, but would require 4 by todays code, only 1 needs to be done as that puts it back how it was. The only time this could change is if any room is gutted. If the space is gutted it needs to be brought up to today’s code.
However, if you were ever going to add any outlets for convenience, doing it while the BX wiring is replaced will be efficient (save money!).
Q: Should I consider other electrical work while having my BX wiring replaced?
A: Yes, I would certainly consider it! In most cases there will be a cost savings to have new electrical added while the BX wiring is being replaced. This is because we are already snaking new wire around your house, so it’s relatively easy to add new electrical.
Some things I would consider: Recess lights, hard wired smoke detectors, additional outlets, 200amp service upgrades. The more we can install at once, the bigger overall savings.
Q: How much is my BX wiring replacement going to cost?
A: Ah yes, the cost question! Customers will often ask us for a ballpark cost without any scope of work. It’s impossible to estimate these jobs without knowing where the BX wiring is. Every house has a different amount of BX wiring left at this point. Some homes are still full of it, and some only have it in a few locations. It varies widely and will depend on how much of the house was remodeled or altered.
We price these jobs per point. Meaning the more outlets, lights, switches the more cost. Without knowing the number of points it’s not possible to estimate these jobs with any accuracy.
Our goal when estimating these jobs is to be as accurate as possible! Throwing out ballpark costs without any information is not our style.
Q: How long will my job take to be completed?
A: Just like the cost question it varies widely from job to job. The more BX wiring that needs to be replaced the more time it will take. On average we can replace 6-8 points (switches, lights, outlets, circuits) per day.
Q: Will I get a letter/certification from your company stating the BX wiring has been removed / replaced?
A: Yes! After every job is completed, we give our customers a certification letter stating the home no longer has active BX wiring.
Looking for more information on BX wiring?
We have some more information found here on our website – https://www.kuhlmanelectricalservices.com/bx-wiring/
If you are looking for even MORE, take a look at this E-Book (or print!) on Amazon, it covers everything related to BX wiring replacement. It’s the perfect guide for any homeowner hiring an electrician to do this work – BX Wiring Replacement E-Book and check out the Kuhlman Electric Youtube Channel for BX Wiring: Top 5 Issues
1250+ Customer Testimonials and Google Reviews
Viktor Shopov
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Timothy Campbell
Had to replace old knob and tube wiring so this was a big job. The team that worked at my house were professional and very thorough. And they were very nice guys. Not only did the job go faster than anticipated, but they cleaned up and made minimal holes in the process. Their ‘rough patching’ made our job to completion very easy!
Mary F.
