Inspecting Electrical Panels

Michael Casey & Associates ©
4/13/2015
Our Agenda
Inspecting Electric Panels
Inspecting panels from the
1920s through today
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A brief history of alternating current
Current flow and neutral separation
Review safety requirements
Service equipment sizes and types
Service and sub-panel inspection
Summary
We only have 90 minutes we cannot cover
all issues found in electric panels!
Presented by Mike Casey
CREIA 2015
Direct Current
• Direct Current must have a direct
and continuous flow of electrons
from negative to positive poles
• Low voltage and high amperage
• Much larger wire size required
• Resistance creates significant
power loss
Standard Terms of Measurement
• Voltage: Pressure behind electrons – similar
to water pressure
• Amperage: Volume (current) – similar to
gallons per minute – only so much can get
through depending upon size of pipe/wire
• Ohms: Resistance of a material to electron
flow – similar to size of pipe or pipe material
restriction - Copper conducts better than
Aluminum
• Wattage: Amps times Volts – measurement
of work a device performs
Electric Panel Inspection
Alternating Current
• Electrons alternate back and forth
along a wire
• Low amperage/High voltage
• Much smaller wire size required
• Able to push current long
distances with less loss and
convert (transform) the power near
the use point (pole transformers)
• This is why we use AC!
Remember:
• The “hot” conductors are called
ungrounded conductors
• The “neutral” is the grounded
conductor (carries current – thus
insulated)
• Equipment ground “ground” is the bare
wire. Should not carry current UNLESS
there is a malfunction – it is the
emergency path back to the
transformer in the event of a fault
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Michael Casey & Associates ©
4/13/2015
Cabinet and Buses
More Terminology
• Panelboard a.k.a. Load center
– Buses and other components, usually
inside a cabinet, where the overcurrent
devices are mounted
CABINET
Or
Enclosure
PANELBOARD
TERMINAL
• Bus (Busbar)
– Where the grounded and grounding
conductors are connected (a.k.a. terminal
bar)
BUSBAR
– Where the overcurrent devices are
connected
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Electricity Myths
Electricity Myths
• Myth: Electricity wants to return to
ground
• Fact: Electricity wants to return to its
source
– In the power grid, the source is the utility’s
transformer and eventually the power generating
station
120-volt
circuit
Normal
current flow
• Myth: Electricity takes the least
resistance return path
• Fact: Electricity takes all available
return paths
– More current flows through a low resistance
path than a high resistance path
Remember, current always wants to
return to its origin - transformer
120 volt
clothes
washer with
motor and
metal case
and threepin flexible
cord.
Resistor in
motor limits
current flow
240-volt
circuit
Normal
current flow
240 volt
circuit does
not use
neutral
unless
there is a
120-volt
component
Copyright Casey, O’Malley Associates all rights reserved. This content may not be reproduced without express written permission.
Electric Panel Inspection
Copyright Casey, O’Malley Associates all rights reserved. This content may not be reproduced without express written permission.
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Michael Casey & Associates ©
4/13/2015
More Terminology
• Ground fault
– An abnormal, low resistance connection
between a hot conductor and metal that is
(or should be) grounded that allows a high
current flow
Current flow
ground-fault
to metal
case of
washer
– Increased current flow should immediately
open the overcurrent device an clear the
fault
– Bonding metal likely to become energized
provides the low resistance path to clear
the fault
120 volt
clothes
washer with
motor and
metal case
and threepin flexible
cord. No
resistor in
case to limit
current flow
Remember, current always wants to
return to its origin - transformer
Copyright Casey, O’Malley Associates all rights reserved. This content may not be reproduced without express written permission.
Service Panel Rating
Panelboard Circuit Capacity
Service Panel Labels
200 Ampere Meter
Electric Panel Inspection
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Michael Casey & Associates ©
4/13/2015
200 Ampere Main
Splices OK in Main Panel (it’s
a junction box)
Direct taps not OK in Main
Panel
Other Deficiencies
Wonder what all those other knockouts are for –
maybe at least a grommet?
Working Clearance?
Electric Panel Inspection
Working Clearance?
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Michael Casey & Associates ©
Cabinet Inspection
4/13/2015
30 Amp Service Panel
• Used in homes as the first service
panel
• Undersized for today’s homes
• Upgrading is required
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Obsolete Panels
• 30 Amp Fuse Service Panels
• Fused Neutral Panels
• Federal Pacific Stab-Loc Fuse
Panels (Type E and F)
• Bull Dog Pushmatic Panels
Problematic Panels
• Federal Pacific Stab-Lok Panels
(people tried to get type F breakers
in type E panels and the reverse)
• Some Zinsco/Sylvania Panels
• Bull Dog Pushmatic Panels
Modern Panels
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100 Amp panels
125 Amp panels
200 Amp panels
400 Amp Panels (sometimes 2-200)
Electric Panel Inspection
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Michael Casey & Associates ©
4/13/2015
Enough Panels?
Subpanel
Grounds and Neutrals not separated
Subpanel Separation, Bonded Grounding
Terminal Bar
200 Amp
Main
Panel
Electric Panel Inspection
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Michael Casey & Associates ©
4/13/2015
Problem Panels
Federal Pacific Stab-lok
Main Bonding
Jumper
Installed –
where do the
equipment
grounds go?
Push-Matic Panel
What the Heck!
Problem Panels
Zinsco
Electric Panel Inspection
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Michael Casey & Associates ©
4/13/2015
Obsolete Equipment
Overcurrent Device Inspection
Subpanel Separation
Double tap OK for this type of breaker
Subpanel Separation Missing
Electric Panel Inspection
Door must open at least 90-deg
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Michael Casey & Associates ©
4/13/2015
Pointed Screws are Bad
Time for a new panelbox
Electric Panel Inspection
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Michael Casey & Associates ©
4/13/2015
2-200 Amp Panels in Parallel = 400
Two 200-AMP service can be 400
“400 Ampere” Meter
How many 30-AMP 120 Volt
circuits are in your house?
We never know what is in there!
Electric Panel Inspection
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Michael Casey & Associates ©
Time for a new panelbox
4/13/2015
Enough Said. The HI did this.
Overheating
All 240 Volt Circuits, no neutral
needed.
Electric Panel Inspection
Overheating
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Michael Casey & Associates ©
4/13/2015
Can you see what is wrong?
Hint
Other Deficiencies
Other Reminders
Multiple neutral wires in 1 lug
Multiple equipment ground wires in 1 lug
Not allowed – clarified 2008 NEC 408.21
Allowed – read the panel label, most allow 2 or 3
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110.14(A) states "Terminals for more than one conductor shall be so identified."
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Other Stuff
Intersystem Bonding
There are other breakers besides Square
D that allow two wires on the terminal
Bonding terminal AKA central point bond terminal
2-terminations allowed
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Electric Panel Inspection
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Michael Casey & Associates ©
4/13/2015
The End
Session Over – Thank you!!!
• Mike Can be reached at [email protected]
Electric Panel Inspection
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