Background
Extensive safety protections have been implemented to protect against personal harm and property destruction due to electrical hazards. But little of these protections are known to the average consumer leaving uncertainty as to what is the correct installation of electrical devices such as receptacles. For the consumer, three organizations are providing their utmost efforts behind the seans to maintain this protection. UL (Underwriter Laboratories); NEC (National Electrical Code) and NEMA; ( National Electrical Manufacturers Association).
As a consumer, buying UL listed products is your first choice of assuring that the correct items are being purchased. After that choice, then having a qualified licensed electrical contractor that understands and meet all building code requirements to present safe and proper installation. It has been our experience that in many cases, the determination of whether to use a 15 amp or 20 amp receptacle is not understood by many. And to be safe, the recommendation is to use a 20 amp receptacle or in Task Lighting product choices, select the 20 amp. Below is a guide explaining how to make the decision of which is the correct choice. You will find that in other than exceptional cases that the 15 amp receptacle is the correct choice.
Why select 15 amp Receptacles?
The circuit protection starts at the circuit breaker panel which controls the maximum amount of current allowed on the line. The National Electrical Code is followed by municipalities to make sure the proper wiring and circuit breakers are used. All Task Lighting Angled Power Strips are internally wired with12 gauge wire which is rated for 20A circuits. However, 20 Amp outlets are not necessary unless a device being plugged in will require a 20 amp circuit. Device manufacturers are required to place a 20 amp plug on their device if it draws more than 20 amps.
NEC NEC 210.21(B)(1)
States: If you only have one receptacle on the 20Amp circuit breaker, the receptacle must be 20 Amp rated.
NEC 210.21(B)(3)
States: If you have multiple 15Amp receptacles on the circuit (like your house, or an Angled Power Strip), then the 15 amp receptacles can be protected with a 20 Amp circuit breaker and 12 gauge wiring is used for the circuit.
With this in mind, you can have a 15 or 20 amp outlet in the strips. It is the total amperage drawn that is being used from the power strip, and if more is drawn like plugging in two toasters and a microwave, if the current exceeds the circuit breaker limit the circuit breaker will trip. This protects the power strip.
The deciding factor on which Angled Power Strip to use depends upon what appliance will be plugged into the strip and the styles preferred. If the appliances are 20 amp rated they will have a 20 Amp plug
which plugs into a "T" 20 amp receptacle 
The common 15 Amp plug two-prong
plugs into a 15 receptacle 
without the "T" slot.With this known, the overriding factor could be the building department requirements in the area and are not using the NEC as their inspection guide; however, this is very doubtful!