GFCI and Knob and Tube Light fixtures

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brother

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"I have learned, in whatsoever STATE I am, therewi
Had a person ask me about adding new/replacing light fixture to knob and tube. I asked why they cant just update the wiring, they say its a money issue. ;-) They wanted to know if they can add another fixture to their living room for knob and tube and replacing the old one they have in another room. I had told him in our area you can replace existing ones, but if there is no ground then the circuit/fixture is to be protected by gfci. The knob and tube I have seen has been around for many years and surprisingly the connections that were soldered are still holding. If its left alone, it appears to be lasting a long time, even though I do recommend people get it upgraded if they can afford to.
Do you alls area allow fixtures to be installed/replace if they have gfci protection?
 
tortuga

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
I would tie into the knob and tube for one light as long as the load calc on the branch circuit checks out, and have a newer panel to put in a GFCI breaker.
Take a look at 394.30 Securing and Supporting.
You need to be extremely strategic about how you tie into it.

Take a look at 410.44 Exception No.2 [2020] or 3 if your on the 2017 code:
Code: 
Where no equipment grounding conductor
exists at the outlet, replacement luminaires that are GFCI pro-
tected shall not be required to be connected to an equipment
grounding conductor.
 
tortuga

tortuga

Code Historian
Location
Oregon
Occupation
Electrical Design
410.42 is still in the 2020, its re-worded it but its not new, you can get a light with no exposed metal parts.

You still run into the issue Eddie pointed out, the temp rating of the wire typically needs to be 90C.
K&T is type R conductor, 50-60C insulation tops.
I have seen a small house fire related to that.
And pretty frequently, i'd say better than 75% of the time when I open up old residnetial lights you find the insulation is all stiff, cracked and brittle.
A jbox and a two foot whip of new 14-2 from the k&t to the light fixture box solves the issue.


Working on k&t to me is like restoring an old classic car in many ways, you'll need a customer with deep pockets and you'll need to be framiliar with the right way to do things that were done years ago.

There can be a bit of liability also, as soon as you touch any of it anything that goes wrong anywhere in the house from now they'll be calling you.
Half the time when I wedge myself up in a old attic there are a ton of other issues with the k&t and we just rewire.
 
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