The main objective of electrical design is safety first and accessibility
of switches and outlets for the disabled second. Adaptibility to lighting
for the visually impaired is also a factor in designing the electrical system
for our kitchen design.
Lighting should be nonglare and areas of lighting should be non reflective,
using low-sheen laminates. Always consider using natural
lighting before incandescent tungsten, halogen or flourescent lighting.
The following should be considered when using these 3 different lighting
techniques.
- Incandescent Tungsten
- A harsher light that creates a sharper edge to objects, allowing them to
be easily differentiated. The yellow and red characteristics of this light
give it a better definition to objects.
- Halogen
- Similar to tungsten, except the color characteristics are more constant
over the color spectrum. It is also a brighter light and adds dimension
if other lighting is used. It is an excellent light to highlight ceilings
and walls so you do not have to diffuse the light in order to reduce glare.
- Flourescent
- A softer light that blends objects into the background, making
them harder to see. It gives off blue and green colors, which are harder
on the eye. There are choices in selecting flourescent bulbs with
different color lighting. A full-spectrum flourescent allows the eyes to see
items in a natural state, but it is still a soft light.
The following lighting is provided in our kitchen design.
- Main Overhead Lights
- 3 x 100w bulbs with dimmer switch is used for the
main lighting in the kitchen. They are positioned on a rail 4 feet apart in
the center of the kitchen. A dimmer switch is used to control the glare and
reflection of objects.
- Sink Lighting
- 2 x 40w flourescent bulbs are used to light the sink.
- Range Lighting
- 2 x 40w flourescent bulbs are used to light the
range/oven area.
Switches and other type of electrical controls for the disabled are
designed for ease of operation and should be placed in an accessible location,
where they can't be accidently turned on by bumping into it. Depending on
the type of disability these can vary greatly and most likely will have to be
used for the individual's need.
- Lights
- There are 3 types of switches that are good choices for lights for the
disabled. Touch sensitive switches, toggle switches and rocker switches
require little force and do not require gripping, twisting or fine finger
dexterity. Any of these three are excellent choices, and depending on the
specific need, the proper selection can be made.
- Main Light
- A dimmer switch with a lever handle was chosen to control the
proper amount of lighting for the main kitchen light fixture. The location
of the switch should not exceed 48 inches and should be placed by the main
door on a wall. Additional switches can be located by other entrances but these
should only be a simple on/off switch with the main dimmer controlling the
brightness of the kitchen lighting.
- Sink and Range Flourescent Lights
- Rocker switches were selected for
sink and range lighting. The best location for these are a few inches below
the over hang of the kitchen counter, roughly at 28-30 inches height. Placing
the switches at the back wall extends the reach of a disabled individual too
far especially over a hot range - so this is NOT a good solution.
- Electric Disposal
- Toggle switch is the safest type of switch between
toggle, touch sensitive and rocker. The location of the disposal switch
should be place where a disabled individual can't turn it on accidently by
bumping it with their wheelchair. The selected location for our kitchen
design is to the left of the left kitchen sink a few inches below
the over-hang of the kitchen counter, roughly at 28-30 inches height.
- Electric Fan
- Control knob with 3 speed lever handle is the selection
for our kitchen design. This variable control allows the user to select the
proper speed with a clicking type lever handle control that accomodates a
multitude of disabilities.
The main objective of providing outlets for the kitchen is safety and
accessibility. Outlets should be provided with ground circuit interupts and
located away from water lines for safety purposes. Some outlets should be
placed under the overhang of the kitchen counter for ease of access.
- 8 Duplex 120 volt Outlets
- The recommended distance between outlets is 6 feet around kitchen
walls and 5 feet for counter space where many of the small appliances
are run. Outlets must be provided in the proper place for microwave
and the refrigerator/freezer. The dishwasher and garbage disposal
can be wired directly into the 120 volt power line in
a junction box on the same circuit or a 120 volt outlet can be provided.
For our kithcen design we wired it directly into the 120 volt power supply.
- 1 240/120 volt Outlet for the Range/Oven
- The range/oven requires both 240 and 120 volt lines for power consumption.
Since these appliances do not require unplugging, hardwiring them into a
junction box is the best alternative.
- Ground Fault Circuit Interupts (GFCIs)
- Ground fault shock occurs due to a loose live wire touching an appliance, and
when touched can cause a shock hazard if there is enough conductance. The
latest electrical code requires GFCIs in bathrooms, garages, outdoor wiring,
and near kitchen sinks. A GFCI works by sensing an imbalance of current load
between the input and output wire and shuts off the power to that circuit or
receptacle within 1/40 of a second. There are three types of GFCIs with
different capabilities. A GFCI breaker is wired at the panel and protects an
entire circuit. A GFCI receptacle protects the outlet it is in and all
outlets after it on a circuit, and finally a plug in GFCI only protects the
receptacle it is plugged into. We recommend the GFCI receptacle since it is
reset at the outlet, protects all other outlets on that circuit, and cannot
removed.
The electrical service coming into the house is based on the power
consumption of all electrical units consuming electricity. By adding up the
power consumption of each appliance, the overall amperage rating of the service
input line can be calculated. As a general rule the following formula is used
in figuring out the service input line needed to drive the electrical system
of a house.
- Assign 3 watts for each square foot of living space.
- Assign 1500 watts for each small appliance circuit.
- Assign 1500 watts for laundry circuit.
- Calculate 40% of 120 volt circuits to consume 100% power.
- Calculate 60% of 120 volt circuits to consume 35% power.
- Assign full load to heavy duty circuits (240 volt)
Once the total power requirement for the house is calculated, because
power(watts) are the product of current(amps) times potential(volts), the
current consumption can be calculated. A 20% reserve is required by the
National Electrical Code (NEC). The following power consumption is
provided for kitchen usage in Table 1.
Table 1. Appliance Power Consumption
| Appliance |
Power Consumption
(Watts) |
| Refrigerater/Freezer |
615 |
| Microwave |
1500 |
| Garbage Disposal |
445 |
| Oven |
2900 |
| Range |
2 x 6 inch setting |
2800 |
| 2 x 8 inch setting |
5200 |
| Dishwasher |
1200 |
| Electric Fan |
150 |
| Lights |
Sink 2 x 40 W |
80 |
| Range 2 x 40 W |
80 |
Main Overhead
3 x 100 W |
5200 |
| Total Wattage |
15,270 |
- Circuit Division
- Circuits can be classified into three categories: lighting circuits,
small-appliance circuits, and individual circuits. A modern kitchen has at least
two small-appliance circuits in addition to individual circuits for major
appliances. All lighting can be part of a general lighting circuit. In order
to determine the best wiring scheme for your kitchen, follow the NEC regulations,
but also use common sense.
- Wiring
- There are two wire and three wire electrical systems for 120 volt wiring.
For a two wire system there is a hot wire and a return ground wire. In a three
wire system there is an additional ground wire that is grounded close to the
outlet. For a 240 volt wiring system there are two 120 volt lines tied
together in series and either one or two ground wires like on the 120 volt line
configuration. Choosing the correct wire size is critical in a circuit. Wiring
is measured by gauge size based on how much current it can handle.
The following wire size is recommended in Table 2. for common house wiring.
Table 2. Residential Wire Sizing Guide
| Wire Size |
Common Use |
Amps |
| #18 |
Low Voltage (LV) |
7 |
| #16 |
LV/Doorbells |
10 |
| #14 |
Light Outlets |
15 |
| #12 |
Small appliances/120v |
20 |
| #10 |
Large appliances/120v |
30 |
| #8 |
Large appliances/120v |
40 |
| #6 |
Single appliances/240v |
55 |
| #4 |
Single appliances/240v |
70 |
The following list of safety tips will protect you from electrical hazards,
both in your daily living and when working on your home's electrical system.
- Always shut the power off at the main service panel to any circuit you
intend to work on.
- Do not overload a receptacle with adapters and extension cords.
- When holding kitchen appliances, do not touch faucets or plumbing pipes,
as most electrical systems are grounded through the plumbing system.
- When adapting a three prong plug to a two prong receptacle, make sure
the adapter is grounded to the screw on the receptacle's coverplate and that
the box is grounded.
- Do not pull a plug from a receptacle by its cord.
- Always unplug an appliance or lamp before attempting a repair.
- Before starting any work, use a voltage tester to make sure the power is
off.
- Never touch plumbing pipes while working on electrical systems.
- Do not splice a length of plastic pipe into a plumbing line that also
serves as a grounding conductor.
- Always wear rubber boots while working on a wet floor on an electrical
system.
[Introduction]
[Layout]
[Electrical]
[Refrigerator]
[Dishwasher]
[Microwave]
[Oven]
[Range]
[Sink]
[Countertops]
[Storage]
[References]
