Specifications

Optima D51 Yellow Top Battery

+ -

120 VAC Power

Inverter

60A Fuse

12 VDC

120 VAC

Outlets

USB Outlet

Vcc - +5VDC

Data -

Data +

Ground

Microcontroller

PCB

Vcc - +5VDC

Data -

Data +

Ground

120 VAC “Hot”

120 VAC “Neutral”

120 VAC “Hot”

120 VAC “Neutral”

Ground

Figure 59 - Schematic Diagram of Wiring from Power Inverter to Outlets

5.8 Power Outlets

In order to keep the power inverter sealed from the elements, it must be mounted inside

the enclosure with all the other electronics. To make the system user friendly, the power

coming from the inverter must be delivered to the exterior of the enclosure in forms that

are most widely used so that most existing electronics can simply be plugged in and

work with no extra efforts. To maintain the resistance to the elements and safety of the

enclosure, weather resistant outdoor outlets should be used. The main concern with

respect to the power to be supplied at the outside of the electronics enclosure is with

the 120 VAC, as this is potentially the most dangerous power form delivered by the

system. After looking at the options available at the local home improvement stores, it

was decided to use a GE 20 Amp Backyard Outlet with a ground-fault circuit interrupter

(GFCI) receptacle. When the system is implemented in Japan, similar equivalent outlets

can easily be swapped in to go with a power inverter that is correct for the region. We

decided to go with a GFCI receptacle to boost safety.

Since the system will be used outdoors where it and the user could be subject to

moisture, the risk of shock is greatly increased, and GFCI outlets can help to protect

against this. A GFCI receptacle compared the current flowing from the hot wire to the

neutral wire. If there is a difference as small as 4 or 5 mA all power to the outlet is

immediately cut off. It is important that we create and use a true ground in this case.

This means that the system will have to be externally grounded in same way. There are

two ways of doing this, the first being to create a new ground at the site the system is