ECN Forum Forums Photo Discussion Forums Violation Photo Forum Will These Devices Recognize an Arc Fault?

I've seen a couple of these on my travels, but never had a chance to look into them more closely.

What type of fuses are used in the main & range pull-outs? Cartridge?

How were the circuits fed from the Edison-base fuses -- Two small appliance plus two general illumination? Or do these pre-date the NEC requirement for two small appliance kitchen circuits?

yes Paul, cartridge fuses, if you look close at the pullout it has 4 round spots, sort of a circle in a circle.

This holds the 2 fuse clips on each side, the screws where then filled with a rubbery substance.

Said substance will many times be seen to burn off , due to years of constant loading, and four 30 A (green colored) fuses

An observance i've commonly pointed out to justify an upgrade.


pre-date many requirements, but many are still in service here. 30A fuses....K&T wiring....we got it all!

The mini-breakers (pictured on the right in Joe's first photo) are still manufactured and sold. As to their reliability, as a child I lived in a run-down third-storey walkup where all the outlets and lights were controlled by a single fuse (replaced by a 15-amp minibreaker).

The thing was pretty reliable and it always "popped" when we had too many high-amperage things plugged in at once. Of course, I can't speak for other people's houses.

What I do remember is that the buttons are hard to press (which could be an issue with people with arthritic hands).

The hospital where I used to work had mini-breakers in the original building(circa 1933). They worked well and would detect arc faults, cut cords and faulty eqipment. They were also a bear when we turned on the window A/C units. We finally wrecked them out in 1995 when the wing was remodeled.

In regards to the question about detection of arcing faults with these devices. The "plug" fuses will detect arcing faults if the magnitude of the arcing fault is sufficient (see the time-current curves for the device). The problem is that often arcing faults are not high enough to trip the overcurrent device. The AFCI will detect and clear more arcing faults than a similar size fuse or cb, but it is NOT the total solution and will not detect all arcing faults. It is an improvement in the right direction, but other protection methods should also be explored.

In regards to reliability, "plug" fuses are reliable when properly applied. I think the reason we have gotten away from fuse panels in the residential market is because of two things. One, at one time there was a quality issue with the construction of the fuse panels. Two, people do not like to replace fuses in this type of application. I really don't think people went to circuit breakers becuase it was a better protective device.

There was a good point about the reliability of overcurrent protective devices. This is often more of an issue in commercial and industrial applications. In these applications one must realize that circuit breakers, since they are mechanical devices must be maintained and tested to assure proper application and operation. See NFPA 70B, NEMA AB-4 and manufacturers literature. The reliability of this device can be adversely affected if these procedures are not followed. We have a presentation on testing and maintenance on our website at www.bussmann.com (go to services then on-line training. Clive Kimblin of Cutler-Hammer also mentioned this in a recent article of the IAEI Magazine (March/April 2002).

Fuses on the other-hand are not a mechanical device, do not require maintenance and testing (although the switch will require maintenance and inspection), give consistant operation regardless of age, and thus are often considered more reliable devices.

I am a firm believer in the replacing of fuses with the fuse-shaped circuit breaker pictured on the right- though, as I read the code, their use is not allowed.
I say "not allowed," as the code calls for smaller plug fuses to be replaces with type "S" tamper-resistant fuses. I believe that this was an oversight by the code panels.
I like circuit breakers because the reset feature makes it less likely that they will be replaced willy-nilly with larger sizes. Why go to the hardware store when all you need to do is push a button, then refrain from using the hot plate and the microwave at the same time?

I believe you could use the circuit breaker style Edison base type device if you met the requirements of of 240.51(B) and the circuit breaker style Edision base device was a listed product. 240.51(B) permits plug fuses of the Edison base type for replacement in existing installations where there is no evidence of overfusing or tampering. I know 240.51(B) refers to a Edison base type plug fuse but if it is a circuit breaker edision base device that is listed I don't think anyone would give you a problem. Proposal time is up November 1, you could always submit a proposal to better define this capability.

breakers that dont work......didnt federal pacific go bust..........

The item on the far right, to my knowledge, is a cheap conversion from fuses to circuit breakers. I've had one before. dunno if those really work.

I see that there's a use for us old timers...:-)

The device on the right, while manufactured by Mechanical Products, is distributed by Cooper/Bussman. It is UL-listed, and has to pass exactly the same tests as any other circuit breaker.

For those who are unfamiliar with the old-time fuse boxes, they were still commonly used in residential construction into the mid-'60's. Of course, they were made in larger forms than the "4+2" shown.

I have such a panel on my house. The circuits divide as follow:
- One cartridge fuse holder has a pair of NON-60 fuses, and is the main disconnect;
- One cartridge fuseholder in not used, as I have a gas stove;
- One 15 amp plug fuse feeds one side of the house, lights and receps both;
- Another feeds the other side of the house;
- A third, fused at 20 amps, is for the electric space heater in the bathroom (primary heat is gas, no fan);
- And the fourth is for an outside receptacle I've added.
( I've used the term "fused" freely....I actually have those little CB's installed).

This house was built in 1940, and wired with an early form of Romex...Cloth wrapper, no ground wire. Apart from the water bond, there is no grounding. All receptacles are two-prong. The only bath recep is part of the light over the mirror. The main room, with almost fifty feet of perimeter, has exactly one receptacle. The only kitchen receptacle shares a single-gang box with a switch for the exhaust fan.