IIRC, back in the '70s, My Father told me of the FPE loss of UL listing, with the 50/2 Stab-Lok Devices being specifically noted.
I do not remember if these were the Full-Size Frames (1" per pole), or the "Slim" Frames (1/2" per pole).
Nevertheless, and as mentioned previously, the site of any FPE (Federal Pacific Electric) Device and/or Panelboard should not be cause for Alarm.
As with any other Manufacturer's Product Line, consider replacement if there is an apparent issue with the Equipment.
Issues would include:
A. Inadequate Capacity of Panelboard,
B. Damaged Equipment,
C. Replacement of Panelboard + Devices being more cost effective than obtaining OEM Devices,
D. Device Malfunction - i.e.:
1.: No trip during extended Overload (> 1.5x OCPD trip rating)
2.: Contacts Failure (AKA "Welded Closed")
BTW: No trip during Ground Fault or Short Circuit (L-N or L-L Fault) is not indicative of Device Failure!
When Devices having the same Time Trip-Current rating are connected in Series, it is completely normal for the "Larger" Size Device to Trip, either with or instead of the "Smaller" Branch Circuit Device.
The term "Non-Selective Coordination" is used to describe this event.
The reason behind this Non-Selective Coordination is simple:
The Upstream Device - most likely a 100A Multipole Device, is of the same Frame Type, Size and trip Characteristics, as the Smaller Branch Circuit Device; however, there is likely to be some Load being drawn by another Branch Circuit, prior to the Fault.
In this case, the Upstream Device reacts to the combined scenario as an Overload condition - which commonly results in only the Upstream Device being Tripped.
Example:
Frame Sizes = 125A, 120/240V, 10KAIC, Time-Trip Curve at 400A = .01 Seconds
100/3 Protecting Feeders supplying a 125A Panelboard, with multiple 20/1 Branch Circuit Devices installed.
Panelboard has the following Loads:
"A": 25 Amps
"B": 15 Amps
"C": 20 Amps
Ground Fault occurs on Branch Circuit #7 (Ph. A), approx. 50 Feet from the Panelboard - which results in an Instantaneous Fault Current level of 385 Amps.
Only the 100/3 Device Trips, as the Load at the Device is 410 Amps (385 + 25).
Back to the FPE devices!
FPE produced more Products, beside the "Stab-Lok" Line.
There are many FPE Devices in use today, in legacy Equipment, such as Zinsco, Westinghouse and GE Panelboards.
The Federal Pacific Transformer Company is still producing Transformers - Low Voltage Dry-Type, and Medium Voltage Oil-Immersed.
I prefer using FP Transformers, as they have the Terminals located more towards the Vertical Middle section of the Enclosure; makes Terminating large size Conductors much easier,
whereas most other Manufacturers place the Terminals at 8 to 12 Inches from the Bottom of the Enclosure; making it very difficult to Terminate large size Conductors.
Provided my 2¢
Leaving the Soapbox
--Scott (EE)
Almost forgot...
Nah ... I'm looking forward to the next 'ground up vs ground down' thread
LOL!
