All frame sizes of the units, originally manufactured by Eaton Cutler-Hammer, are a part of the alert, and may appear to be new or rebuilt but have been changed from the original manufacture design.

MSHA said the circuit breakers may have been purchased directly from the third party, which it did not name, or through a mining supply company.

“There is evidence that some of these circuit breakers have been modified by a third party rebuilder with knock-off 600v and 1000v covers,” the company said.

“The covers are of unknown construction and were not manufactured by Eaton.”

Officials said the labeling on the breakers was also reproduced by the third party to make the breakers look new and legitimate.

Because the covers are not to manufacturer specifications, MSHA said that it may be possible that they may not contain an event such as phase-to-phase or grounded phase.

Additionally, the frames on which the 1000v covers were assembled may only be rated to 600v, and the frames used for both 600 and 1000v models have been rebuilt and may contain parts of unknown origin and specifications.

“Because of the potential for injury and/or death from the failure one of these circuit breakers can cause, they should be removed from service immediately,” regulators said.

To determine if an affected circuit breakers is in use, MSHA suggests moving a fingernail down the square portion of the cover where the handle of the circuit breaker is installed.

If the cover is very smooth, it is likely that one of the hazardous circuit breakers is installed. If it is in use, federal officials said it must be removed from service immediately.

Once the circuit breaker is removed from installation or supply, contact Tom Grace of Eaton/Cutler-Hammer (412) 418-2169 or tomagrace@eaton.com for further instructions on disposal.