Opinion on grouding Knob and tube

[jameselectric]

Got a buddy that has an old house that has old knob and tube wiring and of course no grounding system of course. He doesnt have enuff money to do a whole house up grade, not even enuff for just a panel change. I suggested he at least get some kind of grounding in that house.

2 ground rods and bond the water pipe and (panel). Have any you ever done just the grounding on old houses and not a whole panel change??

 

[acrwc10]

Got a buddy that has an old house that has old knob and tube wiring and of course no grounding system of course. He doesnt have enuff money to do a whole house up grade, not even enuff for just a panel change. I suggested he at least get some kind of grounding in that house.

2 ground rods and bond the water pipe and (panel). Have any you ever done just the grounding on old houses and not a whole panel change??

Your not really grounding the K&T , but the service it is certainly not a bad idea. It could only make it safer.

 

[Jim W in Tampa]

Its a start but wont do much.I would rather see him replace any worn out receptacles and check to see that nobody has insulated this house where wires run.As you know if he waits too long to rewire it might be too late.Many insurance companies will not even insure a house like this.

 

[electricmanscott]

Got a buddy that has an old house that has old knob and tube wiring and of course no grounding system of course. He doesnt have enuff money to do a whole house up grade, not even enuff for just a panel change. I suggested he at least get some kind of grounding in that house.

2 ground rods and bond the water pipe and (panel). Have any you ever done just the grounding on old houses and not a whole panel change??

Do you mean enough? This is not a teen chat room. :roll: Sorry but I HATE when people use "text" spelling. Just a pet peeve and I am grumpy this morning.

Everybody has enough money to do something. It's usually just a matter of whether or not they want to spend it on wiring. Most don't.

 

[infinity]

Do you mean enough? This is not a teen chat room. :roll: Sorry but I HATE when people use "text" spelling. Just a pet peeve and I am grumpy this morning.

Maybe he just needs spell check Mr Grumpy.:wink:

 

[al hildenbrand]

I agree with Jim W's comments about receptacles. I'd add, verifying correct overcurrent protection provided by tamper proof, S type, fuses.

JamesE, from your opening post, I assume you've examined the dwelling electrical system. That you ask about adding a Grounding Electrode System (GES), to me, is quizzical. Maybe the service size is larger than I commonly see in the K&T service centers around me.

Most K&T services have almost no metal raceway or metal enclosure in them. The service center is commonly an asbestos lined wooden cabinet, and the service entrance conductors are on porcelain knobs.

Some K&T service centers are in black painted steel enclosures. Of these, only some are supplied with service conductors arriving in a metallic raceway. All the branch circuits are K&T, with, maybe, one or two added branch circuits worked in with old BX flexible metallic cable, which may, or may not, actually be connected by a BX cable clamp (after all, how does one end BX at an asbestos lined wood box? The clamp will be there to end the cable, but is not mounted to the enclosure.)

There's little metal in a K&T system for the GES to bond to.

Because the common K&T service disconnect was no larger than 30 Amps, the maximum power let thru is only 7.2 kW. This is real easy to overload, with today's convenience electrical home gizmos.

My area defines an existing 30 A (or smaller) 120 / 240 Volt dwelling service as overloaded. Here, one can't add a single outlet, let alone, a branch circuit, without increasing the capacity of the service.

Trying to get by on an existing K&T service, with a small number of branch circuits, tends the loading of each branch circuit and the overall service toward the maximum. Every connection, or termination, through out the wiring system, between the Point of Attachment and the end outlet, is a potential series arcing break down point.

Verifying the greatest number of good connections possible, as well as prudent loading of the limited capacity system, will offer your buddy the best bang for his buck, in my opinion.

 

[jameselectric]

Well there is no ground wire run to any of the circuits and water pipe is not bonded. So doing this would be better than nothing in my opinion. I noticed that most of the 2 wire receptacles have been replaced with gfci receptacles, (no equipment ground) and they are wired correctly.

As for the fuses, just the few they have has been replaced mostly with 15 amp fuses. this is a 100 amp panel. I think the ground wire i pull thru will make things safer, at least for the bonding of the metal pipe.

 

[e57]

Have any you ever done just the grounding on old houses and not a whole panel change??

Yes - is it worth doing - depends - on a lot....

You have a few choices - as it sounds as if you are just trying to wrench what little money your friend has from him.... BTW :roll:

1. Start with the service if capacity is good leave it - if it is grounded in a way that was compliant when installed and has a bonded neutral to "A" electrode - add more electrodes if you like but not necessary if correct when first installed.... Get the drift? Bond neutral in not already...
2. Once you have one grounded panel - see if the others are... Cable with ground or EMT... Ditch all of the fuses if you feel so inclined and swap out the panels.
3. The circuits.... destroy some walls and cielings.... Lighting and recepticals need to be grounded from the panel they come from - take a green or bare from each point back to the panel in the apropriate size - you can daisy chain if you like. However if you open the walls at the first point and see a bare wire - it may already be done!!!!! Just not inside the box.... Popular back in the day...
4. Hit all the apliances too - same way from the panel they come from.

Or save you buddy some money and do one of two things.

1. Save all your scrap and donate it to his house - for weekend work that you teach him to do, and supervise.
2. Install GFI's (while you still can before the code changes) at the outlets - and leave it be.... - It'll get done someday - and there is nothing that makes a two wire system unsafe IMO - so long as there are no grounded surfaces to touch - so around sinks and garage floors etc, should be all that really would be a safety issue...

Nothing wrong with K&T in most residential situations - granted it is in good condition and you haven't isulated..... In most areas of a home spare the bath and the kitchen it has performed and will perform fine for some time to come - no point in replacing it IMO.

Take a look at this as well

 

[al hildenbrand]

this is a 100 amp panel.

For real?

This sounds like there's been a service upgrade, done back in the days of fuses, say the Fifties.

Is that 100 Amp panel supplied by a 100 Amp service entrance through conduit? When was it installed?

 

[yursparky]

Take a look at this as well

That's a great detailed info on K&T, the best I've seen so far, better than what I had in the apprenticeship textbook.

 

[brother]

deleted wrong post

 

[jameselectric]

QUOTE=al hildenbrand]For real?

This sounds like there's been a service upgrade, done back in the days of fuses, say the Fifties.

Is that 100 Amp panel supplied by a 100 Amp service entrance through conduit? When was it installed?[/QUOTE]


Yes there is conduit. I think this was done back in the 1950's. at least that what the records show when the building was built and it looks like there has been illegal (or maybe it was legal to do back then)upgrades maybe in the 60's or 70's. Some one had tapped the line side and installed some regular breakers (30 amp for water heater and another for a dryer). They have the right size wire though, so it can handle the load. Besides its been that way for years. It looks as if the 100 amp panel can is ALREADY attached to the neutral in the service. I think this is how they did those old cans back then.

it would be nice to get rid of those fuses but like i said the money would be an issue. So If i would just put in 2 ground rods (#6) and bond the water pipe(#4) it would be better.

Question:
Would it be code compliant to just run a ground wire to the attic lets say a #10 or # 8 copper (the largest branch breaker is a 30 amp and it goes back to the panel 3 wire dryer the rest are 15 amp) to a centrally located j-box and just drop #12 to the few gfci receptacles instead of running each ground wire all the way back to panel?? This would make this a whole lot easier and faster if its legal but I keep comming up with "all circuit conductors have to be in the same conduit/cable etc.."

 

[al hildenbrand]

Yes there is conduit. I think this was done back in the 1950's. It looks as if the 100 amp panel can is ALREADY attached to the neutral in the service.

OK. This makes more sense.

The 100 Amp fuse center should have been connected (if it wasn't, originally) to the water service, by the Codes of the Fifties and Sixties. I agree that re-establishing the Grounding Electrode System is required.

So If i would just put in 2 ground rods (#6) and bond the water pipe(#4) it would be better.

When the client has limited funds, don't sell him oversized copper. Revisit 2005 NEC Table 250.66. I suspect you only need #8.

Some one had tapped the line side and installed some regular breakers (30 amp for water heater and another for a dryer).

Back in the mid 1900s split bus residential service centers were very popular. Be sure, first, that the breaker subpanel tap, in fact, is bogus. It may just be another set of Service Disconnects -- there can be six, total. If the subpanel feeder conductors are added to a lug that already has another conductor in it, then that's a problem to correct, for sure.

it would be nice to get rid of those fuses but like i said the money would be an issue.

In my opinion, the real issue is the capacity of the service. That's been increased. 24 kW is a nice amount for a simple upgrade from an older, smaller original K&T service. However, this already happened half a century ago, sounds like. Electric hot water and electric clothes dry indicate additional loading above and beyond anything that original system could have handled. Be sure to calculate the existing load to be sure that this 100 Amp service is loaded within capacity.

The fact that the overcurrent protection is fuses is only an end user convenience item. I'm not trying to start a fuse vs. CB debate, only to state that conversion from fuse to CB is a poor first use of limited funds.

Identify any "heavy" loads on the existing K&T branch circuits (such as window AC, Refrigerator, laundry machine, electric heater, the kitchen counter that the coffee maker & toaster are at, etc.) and spend the money on new circuits to these spots. Shed the "heavy" load off the K&T branch circuits. Don't sweat the small stuff.

Would it be code compliant to just run a ground wire to the attic lets say a #10 or # 8 copper (the largest branch breaker is a 30 amp and it goes back to the panel 3 wire dryer the rest are 15 amp) to a centrally located j-box and just drop #12 to the few gfci receptacles instead of running each ground wire all the way back to panel?? This would make this a whole lot easier and faster if its legal but I keep coming up with "all circuit conductors have to be in the same conduit/cable etc.."

Revisit section 300.3(B)(2) and follow the references, first to 250.134(B)Exception No.1 and then to 250.130(C).

just drop #12 to the few gfci receptacles

Again, with limited funds, don't use a larger gauge than the branch circuit is already wired with.

run a ground wire to the attic lets say a #10

It only needs to be equal to the largest Equipment Grounding Conductor.