K&t

[T. M]

I know there is a lot of info on K&T out there but what do you guys usually do with it? walk away? I have a customer who wants to replace old light fixtures and the lights are wired with K&T and no box in the wall. Do I need to install a box? what kind of box? or do you have any other methodes that would help? would it be "grandfathered" in with no box? Do they make somthing for this issue. THANKS

 

[Dennis Alwon]

Here is a link to a pdf file on knob and tube. It may answer a few questions.

Normally I avoid K & T but if I get stuck I will retro a box in the ceiling and install the wiring with the protective covering into a nonmetallic box.

 

[76nemo]

IMO, I walk away if the customer won't pay for new pulls. Although, there are some individuals, very intelligent, like Mr. T, I mean Mr. B/Budget Buster, that still has K&T in their house. That somewhat baffles me, but he knows how to use a megger:grin:

 

[al hildenbrand]

I'm in MN as well.

A new luminaire requires a box, if not present. I let the situation drive the choice of box. Each original K&T lighting outlet was attached in the ceiling in a number of different ways. I find out what that way is first. As a result, I stock as many different types of boxes as I practically can.

The temperature requirements of the new luminaire must match that of the wire. This makes picking luminaires a challenge.

The art of working with K&T is to change what one can to newer methods, while maintianing the old in as safe a configuration as one can. The older building, originally wired with K&T, will have, commonly, only some of the outlets still on the K&T. Those outlets will be the lighting and a few receptacles.

Unless the job is a gut, the wall and ceiling surfaces will remain, so replacing the K&T will be expensive for the customer. If they can afford it, do it, if they will buy it. If they need a particular look of a luminaire rated at 90?C then sell them the new wiring method for that location.

 

[iwire]

that still has K&T in their house. That somewhat baffles me, but he knows how to use a megger:grin:

Unmolested K&T is very safe, ceramic tubes or knobs hold the conductors away from combustibles and each other.

The problems really happen when people (unqualified people ) make changes and additions or when people use 30 amp fuses with 14 AWG circuit.

The circuits still in service in my home are primarily the first floor lighting and a few receptacles, you can tell which ones as I still have two wire receptacles in those spots.

I am not sure a Mega is very usefull for testing K&T.

 

[al hildenbrand]

IMO, I walk away if the customer won't pay for new pulls. Although, there are some individuals, very intelligent, like Mr. T, I mean Mr. B/Budget Buster, that still has K&T in their house. That somewhat baffles me, but he knows how to use a megger:grin:

I live in a metropolitan area of 3 million souls. There has to be 20% to 30% of all the housing stock, here, that was originally wired with K&T, that still has some, if not most, of that K&T still in it. That K&T housing is scattered evenly across ALL economic and physical strata of this Metro Area.

 

[codeunderstanding]

I'm in MN as well.

A new luminaire requires a box, if not present. I let the situation drive the choice of box. Each original K&T lighting outlet was attached in the ceiling in a number of different ways. I find out what that way is first. As a result, I stock as many different types of boxes as I practically can.

The temperature requirements of the new luminaire must match that of the wire. This makes picking luminaires a challenge.

The art of working with K&T is to change what one can to newer methods, while maintianing the old in as safe a configuration as one can. The older building, originally wired with K&T, will have, commonly, only some of the outlets still on the K&T. Those outlets will be the lighting and a few receptacles.

Unless the job is a gut, the wall and ceiling surfaces will remain, so replacing the K&T will be expensive for the customer. If they can afford it, do it, if they will buy it. If they need a particular look of a luminaire rated at 90?C then sell them the new wiring method for that location.

Al. Im from Minnesota also. You seem pretty knowledgable in old wiring. I work on old houses to once and a while and was wondering what you do when you have to hang a new light fixture with the 90 degree wire on the box with that old bx cable from around the 1930s era where the walls are to be left in tact.

 

[nakulak]

A friend of mine lives in columbia (the country). his wife's family has a small factory (large barn type building) with knob and tube. the equipment cords are conductors with a coat-hanger like hook at the end. the feeders run horizontally on the walls just above head height, and to "plug in" the equipment you hook the wire onto the exposed (uninsulated) feeder on the wall. this is what goes thru my mind when anyone mentions knob and tube lol

 

[frizbeedog]

What about grounding for these new luminaires?

What about grounding for these new luminaires?

410.18 Exposed Luminaire Parts. Installing GFCI protection for the circuit sometimes creates problems on these old circuits. Some thoughts on how others deal with this would be appreciated.

 

[mdshunk]

... what you do when you have to hang a new light fixture with the 90 degree wire on the box with that old bx cable from around the 1930s era where the walls are to be left in tact.

One simple answer is to not use that fixture. This can be a pretty simple workaround, since it's normally only flush fixtures that have the 90 degree C labeling. Most semi-flush and most chain hung or pendant fixtures don't require the 90 degree supply wiring.

You might also consider refitting the existing fixtures with some fancy compact flourescents. :grin: They've been out for quite some time:

 

[al hildenbrand]

One simple answer is to not use that fixture.

This can't be stressed enough.

The person (usually the homeowner) choosing the new lunimaire needs the information about the 60?C - 90?C problem. The existing wiring is theirs. The choice of the luminaire is theirs.

As the installer, I am bound by the requirements of the current NEC, which means I add a box to an existing location and make sure the temperature rating on the conductors in the box match that of the luminaire.

If the choice of luminaire aesthetic is more important than anything else, and that luminaire is 90?C and the conductor is 60?C, what does the Code say? Can't do it. One or the other has to change.

What I do, is involve the person driving the aesthetic choice in the decision and negotiate an agreeable price and scope of work.

Marc, I marvel at the installer's head gear. :grin:

 

[480sparky]

Marc, I marvel at the installer's head gear. :grin:

Wow! Gittin' a flo-re-scent! Ain't we right up-town!

Kinda reminds of the all those "Easy as 1-2-3" directions.
1: Remove old fixture.
2: Hang new fixture.
3: Install bulb(s).

I wonder if the 'head gear' is still OSHA approved? :grin:

 

[mdshunk]

Wow! Gittin' a flo-re-scent! Ain't we right up-town!

That fixture actually screws into the old lampholder, just like modern day CFL's, and you tighten the existing shade screws to hold the fixture in place. I still run into them from time to time. I was just surprised to see one being installed in an old video, so I snagged a few scenes for a still shot.

 

[al hildenbrand]

Great find, Marc. I have yet to see one of these.

 

[mdshunk]

Actually, it looks to me that the fluorescent is a retrofit to the existing fixture. Is that true, Marc? Do you know?

Yes, that's a fact. I bump into one maybe once a year. You just took the old shade off, unscrewed the light bulb, screwed in this fixture, and tightened the shade screws to hold the fixture where you wanted it. When I see them, they've normally got about 9,000 coats of paint on them, so it appears like one fixture, but it's really just a fluorescent fixture screwed into the existing flush lampholder.

 

[al hildenbrand]

That's a great example of negotiation with the person driving the aesthetic. Completely side steps the need for a new outlet box.

 

[al hildenbrand]

:grin: :grin:

When I see them, they've normally got about 9,000 coats of paint on them, so it appears like one fixture, but it's really just a fluorescent fixture screwed into the existing flush lampholder.

LMAO.

Great explanation. I can absolutely see it!! :grin:

 

[hillbilly]

I do a lot of repair work on old homes, a lot of them with K&T wiring.

One thing that I use a lot of is 105C shrink tubing...I buy it in 3' rolls from 1/8" to 3/4" diameter.

It lets me sleep better at night.:smile:

steve