Blooper

As hired public-works servicemen, Gus and his co-worker would have been wearing OSHA-approved safety-goggles when servicing the fuse-bank, since there were such large sparks present.

The bright-sparking flash that represents electrical-arcing only occurs after Gus completely removes the fuse; there would only be a spark during the actual "removal moment", while the fuse was in the act of breaking the electrical circuit.