The answer, before the detail
Sparking inside a Black+Decker ES microwave, a breaker that trips when it starts, or a burning smell are all stop-now conditions rather than diagnostic puzzles. Unplug the oven first and read the rest afterwards. On these models the commonest innocent explanation is metal in the cavity or a worn waveguide cover, and both are checked in a minute with the oven unplugged — but the cabinet is never opened, on any model. On the ES models the check that decides the order below is which build you have: a glass turntable, or not.
What the owner actually sees
- It runs for a moment then takes the circuit out — Note whether anything else is running on the same circuit.
- Sparks or flashes inside the cavity — Never run it again to see whether it does it twice.
- A burning or electrical smell — On an over-the-range machine, check whether the filters are loaded with grease.
- The plug or the cord is warm, or the outlet is discoloured — Do not keep using the socket.
- Lights dim elsewhere when it runs — A standard household branch circuit is 15 A or 20 A at 120 V, and a microwave asks for a large share of one.
- NEAR MISS — sparks only with a dish with metal trim — Remove the metal; if the arcing goes with it, there is nothing further wrong.
Most likely first on this family
- Metal in the cavity — foil, trim, a twist tie or a skewer — It leads because it is the commonest explanation for arcing by a wide margin and because it is not a fault at all. Gold or silver trim on a dish arcs exactly like foil does.
- The waveguide cover is soiled, burnt or damaged — It ranks high because it is the one internal-looking part that is owner-replaceable from inside the cavity, without opening the cabinet.
- Grease-loaded filters or a blocked vent on an over-the-range machine — It is ranked here because it explains a hot smell with no arcing at all.
- The circuit is shared, or the outlet and cord are damaged — It is placed here because it explains tripping without any arcing, which the causes above do not.
- A high-voltage component, the magnetron or the diode — It comes last as the diagnosis of exclusion: tripping with nothing in the cavity, clean cover, sound outlet.
The order that finds it fastest
- Take the oven out of service before diagnosing anything — Arcing, tripping and burning smells are all conditions to act on rather than to reproduce.
- Check what was in the cavity — Gold and silver decoration on crockery arcs exactly like foil.
- Look for scorching on the small panel inside — It is replaced from inside the cavity — the cabinet still never comes off.
- Feel the plug and look at the socket — A microwave asks a lot of a shared kitchen circuit at start.
Before you open anything
Safety
Never open the cabinet of a microwave oven. The high-voltage capacitor inside can hold a lethal charge long after the machine is unplugged, and nothing behind that cover is an owner part on any model. Unplug the oven before cleaning anything, leave every door interlock exactly as it is, and do not run the oven empty.
Where the owner job ends
Call once metal, the waveguide cover and the outlet have been ruled out and the oven still trips, arcs or smells hot. That leaves the high-voltage side, and the cabinet is never opened by an owner because the capacitor inside can hold a lethal charge after the plug is out.
Other faults covered for the ES models
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
