[McClary’s Electrical]

Not having any ground fault protection.

Dont have my code book handy to quote a section but I know 210 has something in there about "anytime you work on an old two wire system GFI protection is required." When extending a circuit on a two wire system I change the receptacle I tap off of to a a GFI then I change the breaker to an arc fault. This is enforced by the inspectors. Since he is not extending any circuits, to me that would mean he would only need gfi protection

The requirement to add a GFI to a two wire system is only in order to change to 3 wire receptacles. Adding in line fuses doesn't have a thing in the world to do with that code.

 

[MHElectric]

The requirement to add a GFI to a two wire system is only in order to change to 3 wire receptacles. Adding in line fuses doesn't have a thing in the world to do with that code.

Adding in line fuses is not something I would thought to do if I were trying to price this job. By no means am I saying that this is wrong or inadequate. I am however wondering about the final say of an inspector, and how this measures up with the code. I am not an expert on K&T, therefore like anything I am unsure about I would tend to lean on the side of going "above and beyond" to make sure I didnt get caught with my pants down. What ever your experience is on this subject as long as it matches up with the code, there really isnt much anyone can say against it.

As long as it matches up with the code.

 

[Cletis]

opinion

In my opinion, if you can't get a customer to do a total rewire, then the next best defense is limit the load on old knob and tube and add new circuits to critical points like bath gfci, kitchen, etc.. high load stuff. I've even put old K n T on 5 amp fuses before

The GFCI and AFCI really won't help the problem (AFCI maybe if they would work on old Knob and Tube)

Sincerly,

Cletis

 

[McClary’s Electrical]

Adding in line fuses is not something I would thought to do if I were trying to price this job. By no means am I saying that this is wrong or inadequate. I am however wondering about the final say of an inspector, and how this measures up with the code. I am not an expert on K&T, therefore like anything I am unsure about I would tend to lean on the side of going "above and beyond" to make sure I didnt get caught with my pants down. What ever your experience is on this subject as long as it matches up with the code, there really isnt much anyone can say against it.

As long as it matches up with the code.

That was my original questiona and my point exactly. What code could you use to turn down a 10 amp fuse on 15 amp wire?

 

[Louieb]

Knob and tube is still in the book art 394...done my fair share and the only thing I would be really concerned about is the fused neutral that I have seen in some panels...but greater minds than mine have built it to last 100 years. Ive found most older homes that used K&t were baloon construction type of buildings,which makes running new circuits,allot more easier.this would help the newer electronics everyone wants and has,just leave the K&T for existing lights.

 

[MHElectric]

That was my original questiona and my point exactly. What code could you use to turn down a 10 amp fuse on 15 amp wire?

None that I know of, But I'm also not an inspector.

If simply using a bunch of fuses will pass, and plenty of people here have done it, then I'm happy to say I've learnrd something useful. I just think that a typical inspector would say that this new service would now require all the old circuits to be gfi protected. I could be wrong.

 

[Cletis]

Inspector

Which inpector you talking about Home or AHJ ?

That would be maintainance work putting fuses in I would think no inspection. new cir. inspections..

 

[Wireman191]

Thanks. I'm still don't get how the fuses are safer than CBs though. I have zero experience with fuse boxes here.

Fuses will clear a fault within a half a cycle where as a CB can take 10 or so. If you youtube the difference between a CB and a fuse in a fault you might be amazed how much safer they are.

 

[RePhase277]

A fuse has only one mode of failure, it blows. A CB can fail open, fail closed, fail to trip on thermal, fail to trip on magnetic, etc.

 

[RePhase277]

If you do cut the K&T back to add a box, where will you get the loom and bushing needed to protect the wire? Personally, I think some heat shrink and one of those plastic snap-in bushings would be superior to look, but what do I know. And they say the only proper splice for K&T is solder and tape, a five step process. I'd also put Type S adapters in the existing sockets to keep those nasty 30 A fuses out!

A proper K&T install will last forever. But I have seldom encountered wiring over 40 years old that hadn't been hacked up buy some handyman.

Maybe you can free up just two fuses and give them a 30 A subpanel for a couple of new circuits. Leave the old wiring on the existing fuses, and have some circuit adding capability, including AFCI's etc.

 

[mbednarik]

why the 10 amp fuse in the first place? I agree never more than a 15 amp breaker, becuase i have seen a lot of 12 leaving the basement and then 14 tapped to lights and such.

 

[I_get_shocked]

That was my original questiona and my point exactly. What code could you use to turn down a 10 amp fuse on 15 amp wire?

None.

What code could you use to fail an install for not AFCI or GFCI protecting K&T where there were no receptacle replacements or circuit modifications

 

[don_resqcapt19]

What code could the inspector use to turn down protecting a 15 amp wire at 10 amps?

This one;

210.3 Rating.
Branch circuits recognized by this article shall be rated in accordance with the maximum permitted ampere rating or setting of the overcurrent device. The rating for other than individual branch circuits shall be 15, 20, 30, 40, and 50 amperes. Where conductors of higher ampacity are used for any reason, the ampere rating or setting of the specified overcurrent device shall determine the circuit rating.

 

[Cletis]

Code

I get asked this often by HO's. I just want everything to code.

Well, then your whole house needs to be redone ( I think to myself).

It's a confusing subject to them. They don't realize that code changes every 3 yrs. I'magine how rich we were all be if everyone wanted us to bring their house up to "Current" code.

I tell them I can make it safer by doing x, but , to bring it up to code it would take y.

 

[electricalperson]

Why is this?

because breakers can fail and not trip while fuses will trip faster and are more reliable

 

[Hairbone]

It sounds like you are a crook. Why have you advised what you are proposing?

I don't think he sounds like a crook at all. It is not like this is an easy job or milk run to put a load of cash in your pocket in a day. For the HO they might not be wanting to invest in an upgrade, but it sounds like this house is long overdue for a major overhaul. Many guys just don't have the experience with K&T and I don't blame the guy for pricing a new install per current code.

 

[MHElectric]

None.

What code could you use to fail an install for not AFCI or GFCI protecting K&T where there were no receptacle replacements or circuit modifications

Answer this question,and Ill be happy... But I dont have any honest answers to provide, only my thoughts.

 

[RePhase277]

This one;

Don, I agree that an inspector could use that code to deny the use of 10 A fuses on 15 or 20 A circuits. But what inspector would actually argue that a 10 A fuse would be unacceptable on K&T?

I think the intent of the Code in this case is to limit the specific INSTALLATION of a new 10 A circuit. One might argue that it IS a 15 A circuit because it was intentionally installed that way. Does using a 10 A fuse on what was originally a 15 A circuit instantly transform it into a 10 A circuit? In this case, where old wiring has been overprotected by using a smaller fuse, I don't think any reasonable inspector would turn someone down on that alone.

 

[Whatevva]

K/T doesn't need to be hacked up to be bad. They didn't use thermo-plastic on wire back in those days, it was a form of rubber, and as years go by, it's cracking and breaking off. Mix that with a few 30 amp fuses and we've got bare toaster wires in the walls! This stuff needs to go...

 

[mbednarik]

because breakers can fail and not trip while fuses will trip faster and are more reliable

i have seen fuses fail the blow, water and elements build up inside and prevent them from blowing where a breaker would have tripped.