Electrical Wiring in the Home/knob and tube/dryer


can my knob and tube handle this dryer


Knob and tube of course had no earth ground path,  that is a possible issue on some devices and not so much on others,   for example double insulated tools.

If you are asking if knob and tube is weak or inadequate as a TYPE of distribution,   the answer is no, other than the lack of a ground circuit, but you can install GFCI outlets that do not depend on a ground for added safety on knob and tube systems,    but with a dryer sizing a GFCI and avoiding nuisance tripping can be a tricky ordeal,    

It is not cheap to replace knob and tube,    but you can replace circuits one at a time,   to spread the cost over time,      but a big expense is a new main panel,   where you really should start, that way you have a new 200 or whatever size is adequate for the structure,  with a ground circuit,  an outside earth ground rod or grid,  and start replacing circuits one at time,        

Knob and tube was clever in that is used free air and space around it to insulate,  one of the best insulating procedures there is,    but then the need for insulation has to be rolled under and around the knob and tube versus blown in,    which is not permissible with knob as it removes the free space,  

I know this is going to be a cost evaluation, and your budget is your budget,     is this dryer a replacement for an existing dryer or is this a new convenience you are trying to add?

I am assuming it is a total electric dryer, but it could be gas with the need for electrical for the blowers and controls,  a MUCH LIGHTER LOAD<   and much more efficient,    

Ideally with the codes getting more and more restrictive as old knob and tube gets older and older,     a total new system is the cure,  but that is sticker shock no one wants to think about,     but I have been through a house fire,     now get this,   a modern 200 amp supply,  and a damn coffee maker we use twice a year     failed in the cord  which by visual inspection was just fine,          [I personally think we suffered an electrical surge,  either from something external to the house,   [and I have a whole house surge protector provided by the utility]  or in some cases    a coffee maker, some heaters,   have an INRUSH like a motor or induction load,  even though it is a resistive load by definition.

I bought an old home in a small college town for my son to stay in versus dorms,  and it was 80% retrofitted,   new main,  new romex but two knob and tube circuits remain to be retrofitted,   as it goes, most people for whatever reason  tackle the easy stuff first,  when they should tackle the more difficult first,     

But my modern house caught fire,  and my old partial knob and tube has no electrical issues,  so go figure,     

You didn't say, again , if it is total electric or you just need electric to control the gas controls,

And I understand the short question,  most of these free sites either never reply or give out some short unexplained no detail answer,          but about.com does a good job and they do it for not a dime,   that is why I volunteer here,   if they stack up on questions they are right on me to help out,          

    knob and tube   assuming      ASSUMING the insulators and all components are in decent condition,     will handle the rated current with no problem     there is really nothing wrong with knob and tube,[other than lacking ground] and other than most suffer from age and deterioration,   

Remember  breakers protect wire,  not devices.  What you need to look for are these considerations:

The general overall condition of the knob and tube system   WHAT IS THE WALLS?   [any cracked insulators  basic conditions like that]

Then I have no information on the dryer,   but it will have an amp rating on it,   and it will have inrush   as it is electric with a motor, at the very least

Motors are induction loads,  light bulbs are resistive loads,    a circuit with straight resistive loads are sized differently than circuits with INDUCTIVE loads, because the inductive has this inrush to deal with,        

It is preferable and most always by code that the dryer be on a dedicated circuit,  is that the case?

If the dryer is rated at 20 amps and the circuit is rated at 15  NOT ADEQUATE  but it would be no if it was romex off a new panel and breaker, by just the load rating to circuit rating,         

Is the circuit dedicated,  will the dryer be the only load on that circuit?

What is the amperage rating for the dryer, and what size  [in amps] is the circuit you want to use?     

Now I say there is nothing wrong with knob and tube   that is from a pure technical viewpoint, with tons of caveats,   but there could be an oven,  a refrigerator,  or some other device on the knob and tube that is even more marginal than the dryer,  

This would be a perfect time to have    AT THE VERY LEAST   an inspection by a qualified electrician,    just so you know what kind of risks you may or may not be living with,    

 it is of course preferable to have new romex  type wiring,,  BUT an expensive project along with sourcing the right contractor,   which is more than half the battle,   

The house must be of some age,    but that does not mean the knob and tube is deteriorated,   it does need to be inspected,        

If it is in good condition,   large enough to handle the dryer load,   it would operate the dryer,  I would certainly want to put a GFCI at the bare minimum on the end of the knob and tube, for a dryer where there is normally a washer and water and all that

A lot of knob and tube circuits have deteriorated over the years,     that is the issue you need to focus on first,      even if were a can opener  you would not want it powered by a deteriorated knob and tube circuit,      nor would you want it powered by a rotten run of old insulated cable,

Is it possible  yes,  is likely to be a code issue or lack of power issue,  yes,    but because I know you have knob and tube and right now I am assuming it is all knob and tube,    not in the midst of a circuit by circuit retrofit,   you really need an inspection   and you need a non biased inspection,    not someone trying to sell you a rewire job,     

I am so frustrated with the quality and give a crap attitudes of most any contractor anymore,    yea there are really great ones,  but for every great one there are a hundred two man band  jack of all trades half ass no skills,  should be banished businesses,    

At this point if your budget allowed it,   and you could afford a new system complete,   that is the way to go,    but if there is a way to maybe run some romex to the dryer off a dedicated breaker,   and the inspection indicated the knob and tube was in acceptable condition,  there is a possibility that you could get the dryer wired up and safely but at some point down the road,   the knob and tube will have to go,       

Again it can be done in steps,  better to bite the bullet, and get it all at once, but it is possible to do one circuit at a time as you can afford it,          

So after all that      if the dryer load can be handled by a knob and tube circuit,  with no blown in insulation, no scabbed on circuits or loads,    the dryer will run, the wire will not get warm or hot,      

Maybe this is not a case of funds,   if so,   get a new service,       but I am betting you are trying to get along with a dryer without spending fortune right now,      

It will depend on the structure size, the access,  and all that,  to guess at an inspection cost,   but if you had ever gone through a fire, [being in it, was less traumatic than the mess later,  not just the physical mess, but crooked contractors, crooked insurance people,  delays, wrong primer,  on and on and on and on,    getting out alive was a piece of cake,    comparatively,

I will sleep better,  you will sleep better,  and you WILL BE SAFER if we back up and go for a qualified inspection of the entire electrical system,        which should provide you with options, or mandates, or whatever,          let me ask this,    what does your insurance company think of the knob and tube?   Do they know?   Did someone hide it from you when you purchased the home?

Might be some recourse there,  but your safety and your family if that is the case    being safe is way more important than a dryer,     it is a bitch    I get a lot of these questions and believe me I understand,    but the issues are not going away,     if the inspection says no way there is enough  WHATEVER to run the dryer,  be it a large enough or good condition circuit,  or a code violation,    best you know now,          

Technically if the knob and tube is good   free space, all around,  large enough to handle the dryer current   yea it will work,     but again no ground so the best you can do is a GFCI     ON THE END ,    THAT WOULD BE A get by situation,      

Do me  a favor and look into getting a complete inspection,    I will help you find a contractor,  I will speak with them personally if you want,   

[here is a little trick that is becoming more and more a problem,  you look online for contractors and they have a beautiful website with all kinds of pretty pictures and bragging on themselves,   but if you go to their main offices,  it is very likely the real business looks nothing like the website,    so as you are interviewing possible contractors,  do NOT let them drive up,  do their thing and drive away,   you GO to their offices and look around,  it could very telling]

A long answer with most likely not what you needed,   but again, go through a home fire, and cost drops way down the priority list.

Get an inspection,   continue to use the laundry, or wherever,   hang the clothes on a line,    but know what you are living in before anything else,  please,

If you need or want help  selecting a contractor,   evaluating the pricing,  whatever it is    let me know,    glad to walk you through the process and provide the whys and why nots,    and as far as paying for someones recommendations,   think twice,  that is an expense you can easily get around, and put towards the inspection, adding a circuit whatever,   these lists are not full proof, and nothing you cannot evaluate on your own,  with minimal effort,          let me know what you decide and how things progress,,,,,,,,,,,,,,,,          


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Will Babbitt


Electrical issues of all types, wiring, control, appliances, components, specialty in Electric MOTOR or APPARATUS trouble shooting, electric motors, electrical problems, single phase, three phase, DC, capacitors, elevator MG-Sets, modifications, reverse engineering, VFD Drives, single to three phase convertors. Repair of most any electrical/mechanical/electronic apparatus, OEM, AC, DC, Industrial Applications, Three phase, single phase failure mode, determining the root cause of the equipment failure BEFORE failure repeats, Antique appliances, electric motors, fans, ceiling fans, base mount fans, poor equipment performance, Modifications, habitual failures, vibration, redesign, obsolete issues, collectible items restored, rewinding. Owner of EMR Repair Inc www.emrrepair.com More information on electric motors, under Engineering/Motors Ask about any electrical or mechanical problems in the home, office, or even at your work. B2B or business to business CONSULTING I can do but it would be a much more complex issue, that would require a significant amount of time. repair@mearservice.com from there we can discuss and begin work on about anything. Industrial electric motors, controls, troubleshooting, vibration, alignment, any type of industrial or commercial electric/electrcical equipment For the home owner, renter, apartment if you have odd things going on, describe to me, photos are normally very helpful, appliances, heating and air conditioning issues, light switches, installation, DIY PROJECTS FOR THOSE NOT EDUCATED IN ELECTRICAL, we can do some things, but for safety and sanity reasons, I may refer you to a local electrician, and help you find one, help you with pricing and even speak directly with anyone you hire if you have issues,


Over thirty years with a major repair and sales company, VP of Operations, and former owner of my own specialty repair shops, MEAR Services local to Kansas City Missouri EMR Repair Inc., located in Kansas City Missouri, 2014 sold both businesses to JCI Industries, Lee's Summit Missouri wbabbitt@jciind.com Evaluation and repair of electrical/mechanical apparatus. Electrical and mechanical repairs, trouble shooting including, vibration and balance issues. About.com provides this service, and the huge costs to provide help on about any subject. They provide the servers, the people to vet the experts, costs that would be the same as operating a good sized business, They should be appreciated for what they do, the huge costs and the great help they provide for free, Electric motor questions, can be answered here but there is a dedicated category that has other experts to help and add to a solution. Other common questions, are noises in the walls, breakers tripping, devices not starting or shutting down for no apparent reason, smoke alarms buzzing, thermostat change outs, or sizing wire or needing information for a new project, but anything can be resolved, anything, with enough effort and patience, DIY, with electrical is possible, but in most cases the use of a simple ohm meter or volt meter is needed, they can be purchased at any hardware store for a few bucks. If you have smoke, or smell smoke, don't be writing me, call 911 the Fire Department has no problem looking for smoke smells, better then spraying water on a blazing fire. DO NOT GET CAUGHT INVESTIGATING AND TRAPPED IN A BASEMENT LOOKING FOR A BLOWER FAILING< As to the tip jar, it is up to you, it is appreciated, every expert spends out of pocket that I know, we spend on IP time, computer wear, printing documents, books, and of course our time, but if we prevent a $400 service call, we did well,

Former IBEW, EASA, IEEE, UL, ..............


10 plus years, various Technical Schools, followed by Industrial College Credit and non Credit Courses, electronics courses, experience in most any electrical apparatus, electric motors and generators, AC OR DC, fractional to above 5000HP, other electrical apparatus, slip rings, sleeve [plain] bearings, lubrication, identification-no data plate, control components, service and sales. I have continued night schools for decades, the list is extensive. I have been in the business of repairing most anything with wires or mechanical parts for decades, I have some helpful hints and directions you won't have to dig up. Or hopefully not have to pay a huge service call invoice to find.

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