The overwhelming reason properties in Baltimore City and Baltimore County are not prepared for rental home inspections is inadequate smoke detectors and carbon monoxide (CO) detectors.
And important point to understand is that on January 1, 2018, a new law went into effect for the entire State of Maryland stating that smoke detectors (and CO detectors) must be either hardwired (AC) or 10-year sealed battery. Removable-battery alarms and plug-ins are no longer allowed. Therefore, this law applies to both Baltimore City and Baltimore County rental inspections.
In Baltimore County the smoke detectors must be hardwired on every level and interconnected. Wireless interconnection is acceptable as long as each unit is hardwired. That means they are hardwired but not hardwired to each other (what electricians refer to as daisy chaining). The pic below is an example of this type.
hardwired, wireless interconnect, combination smoke/CO alarm. Perfect for Baltimore County.
Please note: In Baltimore County, the CO detectors do not have to be hardwired, although they can be. If they are not hardwired they must be the 10 year, sealed lithium battery type. This is why I recommend using hardwired combination units in Baltimore County.
In Baltimore City you also need a smoke detector and a carbon monoxide detector on every level of the unit, although they are not required to be hardwired or interconnected. They can be either hardwired or 10-year sealed battery. Removable batteries and plug-ins are not allowed.
The pics below are of a hardwired, wired interconnect combination alarm, and a 10-year sealed battery combination alarm, respectively.
hardwired, wired interconnect, combination alarm
10 year, sealed battery combination alarm