Permission to use an approved type of meter is effective only for those types which are of the same electrical design and assembly as the type approved. If the manufacturer of an approved type changes its construction in a manner that may affect its operation or accuracy, the sponsoring entity or the entity intending to use the modified device shall notify the commission staff specifying the changes. If the commission staff determines that the change is significant, the meter will be considered a new type and subject to approval. Minor variations in mechanical construction which are not of such character as to affect the electrical operation will be permitted in meters of the same type, but the commission staff shall be notified and reserves the right to make the determination.