Term
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Definition
Flow or rate of flow of electrical charge through a conductor.
Unit of measurement.
AMP (A) |
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Term
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Definition
| Electrons move around the circuit in one direction only. |
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Term
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Definition
Alternating Current changes direction.
Electrons first move in one direction ,stop then flow in another |
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Term
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Definition
| Unit of electric potential,the potential difference between 2 points on conductor carrying a current |
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Term
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Definition
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Term
| Resistors Connected in SERIES |
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Definition
Current flows in turn through each of them.
R1+R2+R3...etc =RESISTANCE TOTAL |
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Term
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Definition
Current passes through them at the same time,each provides its own circuit.
1/R1 + 1/R2 + 1/R3 = 1/TOTAL=Resistance total |
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Term
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Definition
| is concerned with the relationship between I,V and R |
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Term
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Definition
Measured in WATT
1kw =1000watts
Electric Power can be calculated by multiplying VOLTS x AMPS |
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Term
Single Ring Circuit
Should serve a floor area NO LARGER than |
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Definition
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Term
| 3AMP Fuses for appliances rated up to |
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Definition
| 750watts (lamps ,clocks etc ) |
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Term
| 13AMP Fuses for larger appliances rated up to .. |
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Definition
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Term
| Preliminary Electrical Checks |
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Definition
Check fuses for size n condition
EARTH CONTINUITY TEST
SHORT CIRCUIT TEST
POLARITY TEST |
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Term
Earth Continuity Test
SET METER TO OHMS |
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Definition
One test lead to Earth pin on the plug or first available earth connection.
Other test lead to each earth connection and appliance CASING/PIPEWORK/CONTROLS IN TURN
EACH RESISTANCE s/b LESS than 1 ohm |
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Term
SHORT CIRCUIT TEST
LIVE-NEUTRAL |
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Definition
set to measure resistance =OHMS
Connect test leads across main LIVE & NEUTRAL.
Operate switches in their correct sequence.
Meter measuring continuity=short circuit
Should read NOT LESS than 10ohms |
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Term
EARTH CONTINUITY TEST
READING SHOULD BE |
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Definition
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Term
SHORT CIRCUIT TEST
LIVE- NEUTRAL
Reading S/B |
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Definition
GREATER THAN 10. OHMS
OPERATE ALL SWITCHES IN CORRECT SEQUENCE.
READING LESS THAN 10 OHMS
S/B INVESTIGATED |
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Term
SHORT CIRCUIT TEST
LIVE TO EARTH |
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Definition
Ensures there is no electrical path between LIVE AND EARTH
SHOULD READ O.L |
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Term
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Definition
| Is a LOW RESISTANCE PATH between LIVE and NEUTRAL that allows an excess current to flow. |
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Term
SHORT CIRCUIT
CAN BE DETECTED BY |
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Definition
Resistance testing provided CIRCUIT SWITCHES ARE OPERATED IN CORRECT ORDER
(Current flows down the path of least resistance) |
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Term
EARTH CONTINUITY TEST
RESISTANCE OF THE EARTH PATH MUST BE AS LOW AS POSS...WHY? |
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Definition
ELECTRICAL CURRENT WILL FLOW DOWN PATH OF LEAST RESISTANCE.
A LOW RESISTANCE PATH WILL QUICKLY ALLOW A LARGE CURRENT TO FLOW,THIS WILL BLOW THE FUSE AND TERMINATE SUPPLY |
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Term
POLARITY TEST/REVERSE POLARITY
CHECKS CORRECT VOLTAGE MEASURED AT
L,N AND EARTH CONNECTIONS |
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Definition
PERFORMED WITH THE ELECTRICITY TURNED ON
(Can only be done are prelim checks have been carried out) |
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Term
| POLARITY TEST/REVERSE POLARITY |
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Definition
meter to VOLTS
Connect Test leads between L and N
(Reading should be 240v)
L and E (reading s/b 240v)
N and Earth (reading s/b LESS than 15v) |
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Term
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Definition
| A sacrificial protection of the circuit , it protects the circuit from an overloaded current. |
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Term
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Definition
In this type of system
Neutral and protective functions (earth) are combined in a single conductor in part of the system. |
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