Wireless dog fences require understanding of the function of the receiver color. The transmitter signals in a range (confinement area) that is intercepted by the receiver color. If the color ceases blocking the signal (ie leaves the confinement region), a correction is made. What this means is that if there is something that causes the collar to lose track of the signal, static correction will be done. This answers your question: Depending on the design of your dog’s metal box, it blocks the signal radiated from the transmitter, equivalent to the dog who left the containment area from the “viewpoint” of the receiver There is a possibility. The correction will then arrive. When placing the collar of the receiver in a metal box make sure to keep it away from the dog’s neck all the time.