OP
amberleaf
What is a Portable Appliance?
Generally, portable appliances can be thought of as electrical goods that can be plugged into a power socket. This includes such items as FAX machines, toasters, drills etc. Testing incorporates 110 volt and 400 volt (3 phase) appliances , not just mains powered equipment (230 volt).
When is testing required?
•Testing is a requirement whenever:
•Employees use electrical appliances
•Customers (ie non-employees) use electrical appliances
•When electrical goods are re-sold or hired
•When appliances have been repaired
What has to be done?
Under the Electricity at Work Regulations 1989 in particular, and other Health & Safety requirements,
it is generally agreed that a planned regime of testing is the only way to
show that a proper ‘duty of care’ has been taken to protect users from electrical shock and the hazard of fire.
Unless the equipment is to be tested every time it is to be used, you will need to keep records to show when testing has been carried out, test results and who did the testing.
Equipment that has passed its testing should be marked on the outside to show the date when re-testing is due.
The equipment should not be used after this date. Showing the test date will have little value to the average user who will not have the knowledge to decide Test intervals are determined by considering the nature of use, frequency of use and
Test intervals are determined by considering the nature of use, frequency of use and working environment. Equipment used in an office where it is not moved eg a FAX machine will not require testing as often as the kitchen kettle, which in turn may not require testing as often as an extension cable that is being used outdoors on a building site.
A principle of electrical safety is that there should be 2 levels of protection. Earth + insulation
(an earthed appliance) are known as Class 1 appliances. Class 2 appliances are
protected using insulation + insulation (a double insulated appliance).
Nearly all of the equipment we meet falls into either Class 1 or Class 2. We will
concentrate on these here, but seek specialist advice if you feel that you have equipment that falls outside these classes.
All test equipment should be calibrated at intervals determined by the Test House.
Without using calibrated test equipment the tests are all but meaningless. It is easiest to conduct the tests using equipment especially designed for such testing, but separate items of equipment can be used where the Inspector has sufficient knowledge. Many PAT testers are designed to store and then download the test results to a PC, although manual testers can be used where results are recorded by the Inspector.
TESTING PROCEDURES :
Before undertaking any electrical tests you should always conduct a visual inspection, looking for damage exposing live parts, missing insulation, damage to the earth conductor, loose cable grips, checking for correctly rated fuses etc. Only when you feel that the equipment has passed all visual checks should you move on to conduct the appropriate
electrical tests. Please remember to switch on the item before conducting further tests. Where possible, always use an RCD (Residual Current Device), with a trip value of no greater than 30mA, in the supply to the test equipment. This precaution should prevent any shocks sustained by the Inspector from proving fatal.
Class 1 Protection :
This is the class of protection we meet most frequently. There are 2 tests that must be carried out, once a careful visual inspection has been conducted, and the equipment has been deemed fit for electrical testing.
EARTH BOND TEST : Must be completed with a successful test result before commencing the Insulation Test. ,
A substantial current is passed down the earth conductor, to the external metalwork and returns via the probe or crocodile
clip which is connected to the test equipment. The value of the resistance is shown on the tester. When selecting a test point
on the case, bear in mind than many decorative finishes are also poor conductors. We are looking for a low value (< 0.1Ω). In the case of a failure, the earth return should present a lower resistance path to earth than that offered by the human body. Where long cables are being tested, the Inspector will need to make an adjustment to the value returned by the test to allow for the resistance in the cable itself, before they can be sure that the nett resistance value is low enough to be considered safe. How this adjustment is calculated is outside the scope of this document.
A high test current is used so that should an earth conductor be too flimsy to provide protection under fault conditions, it
will fail (melt) under test. This will allow the fault to be remedied before re-testing, and its eventual return to service.
Do not touch the equipment while conducting the test. ←←←
INSULATION TEST :
A test voltage is applied, usually 500V DC, between the Earth conductor and Live & Neutral linked together.
We are looking for a high value (>1MΩ), and results showing infinity (∞) are common.
Do not touch the equipment while conducting the test.←←←
PAT Testing and Portable Appliance Testing information
Fuse Ratings
For the convenience of users, appliance manufacturers have standardised on two plug fuse ratings- 3A & 13A and adopted appropriate flex sizes. For appliances up to 700W a 3A fuse is used, for those over 700W a 13A fuse is used.
A variety of fuse ratings (1A, 2A, 3A, 5A, 7A, 10A 13A common ratings in bold) are available.
The fuse in the plug is not fitted to protect the appliance, although in practice it often does this. Appliances are generally designed to European standards for use throughout Europe. In most countries the plug is unfused. If an appliance needs a fuse to comply with the standard it must be fitted within the appliance. The fuse in the plug protects against faults in the flex and can allow the use of a reduced csa flexible cable. This is advantageous for such appliances as electric blankets, soldering irons and Christmas tree lights, where the flexibility of a small flexible cable is desirable.
With some loads it is normal to use a slightly higher rated fuse than the normal operating current. For example on 500 W halogen floodlights it is normal to use a 5 A fuse even though a 3 A would carry the normal operating current. This is because halogen lights draw a significant surge of current at switch on as their cold resistance is far lower than their resistance at operating temperature.
The Regulations implement an EC Directive aimed at the protection of workers and the "general duties" will require the need to:
a) Make sure that equipment is suitable for the use that will be made of it.
b) Take into account the working conditions and hazards in the workplace.
c) Ensure equipment is used only for operations for which, and under conditions for which, it is suitable.
d) Ensure that equipment is maintained in an efficient state, in efficient working order and in good repair.
e) Provide equipment that conforms to EC product safety directives.
f) Plus certain other general duties and specific requirements etc.
VISUAL INSPECTION
In practice approximately 90% of all equipment defects are found during a preliminary visual inspection.
(1) The exterior of the equipment will be inspected for:
(i) physical damage.
(ii) signs of overheating
(iii) signs of ingress of liquid or foreign materials.
Particular attention will be paid to possible physical damage at accessible mains components such as switches, fuses and appliance couplers.
(2) All mains and power cords, including interconnecting cords, will be checked for physical damage. All flexible cords showing any sign of damage will be replaced
(3) Where re-wireable plugs or appliance couplers are used, their covers will be removed, and (i) terminations and cord grips will be checked for tightness.
(ii) terminations will be checked for correct polarity.
(iii) conductors will be checked for damage or loose strands.
(4) Operator accessible fuses on the outside of the equipment will be checked for correct type and rating. If the equipment manufacturer has specified a particular rating for the plug fuse, this will also be checked. If the manufacturer has not specified a fuse rating for the plug the preferred fuse size will be determined and the correct size fitted, and check that properly manufactured cartridge fuses to British Standards are used.
5) Plugs with none insulated pins will be replaced with British Standards approved Insulated ones.
Generally, portable appliances can be thought of as electrical goods that can be plugged into a power socket. This includes such items as FAX machines, toasters, drills etc. Testing incorporates 110 volt and 400 volt (3 phase) appliances , not just mains powered equipment (230 volt).
When is testing required?
•Testing is a requirement whenever:
•Employees use electrical appliances
•Customers (ie non-employees) use electrical appliances
•When electrical goods are re-sold or hired
•When appliances have been repaired
What has to be done?
Under the Electricity at Work Regulations 1989 in particular, and other Health & Safety requirements,
it is generally agreed that a planned regime of testing is the only way to
show that a proper ‘duty of care’ has been taken to protect users from electrical shock and the hazard of fire.
Unless the equipment is to be tested every time it is to be used, you will need to keep records to show when testing has been carried out, test results and who did the testing.
Equipment that has passed its testing should be marked on the outside to show the date when re-testing is due.
The equipment should not be used after this date. Showing the test date will have little value to the average user who will not have the knowledge to decide Test intervals are determined by considering the nature of use, frequency of use and
Test intervals are determined by considering the nature of use, frequency of use and working environment. Equipment used in an office where it is not moved eg a FAX machine will not require testing as often as the kitchen kettle, which in turn may not require testing as often as an extension cable that is being used outdoors on a building site.
A principle of electrical safety is that there should be 2 levels of protection. Earth + insulation
(an earthed appliance) are known as Class 1 appliances. Class 2 appliances are
protected using insulation + insulation (a double insulated appliance).
Nearly all of the equipment we meet falls into either Class 1 or Class 2. We will
concentrate on these here, but seek specialist advice if you feel that you have equipment that falls outside these classes.
All test equipment should be calibrated at intervals determined by the Test House.
Without using calibrated test equipment the tests are all but meaningless. It is easiest to conduct the tests using equipment especially designed for such testing, but separate items of equipment can be used where the Inspector has sufficient knowledge. Many PAT testers are designed to store and then download the test results to a PC, although manual testers can be used where results are recorded by the Inspector.
TESTING PROCEDURES :
Before undertaking any electrical tests you should always conduct a visual inspection, looking for damage exposing live parts, missing insulation, damage to the earth conductor, loose cable grips, checking for correctly rated fuses etc. Only when you feel that the equipment has passed all visual checks should you move on to conduct the appropriate
electrical tests. Please remember to switch on the item before conducting further tests. Where possible, always use an RCD (Residual Current Device), with a trip value of no greater than 30mA, in the supply to the test equipment. This precaution should prevent any shocks sustained by the Inspector from proving fatal.
Class 1 Protection :
This is the class of protection we meet most frequently. There are 2 tests that must be carried out, once a careful visual inspection has been conducted, and the equipment has been deemed fit for electrical testing.
EARTH BOND TEST : Must be completed with a successful test result before commencing the Insulation Test. ,
A substantial current is passed down the earth conductor, to the external metalwork and returns via the probe or crocodile
clip which is connected to the test equipment. The value of the resistance is shown on the tester. When selecting a test point
on the case, bear in mind than many decorative finishes are also poor conductors. We are looking for a low value (< 0.1Ω). In the case of a failure, the earth return should present a lower resistance path to earth than that offered by the human body. Where long cables are being tested, the Inspector will need to make an adjustment to the value returned by the test to allow for the resistance in the cable itself, before they can be sure that the nett resistance value is low enough to be considered safe. How this adjustment is calculated is outside the scope of this document.
A high test current is used so that should an earth conductor be too flimsy to provide protection under fault conditions, it
will fail (melt) under test. This will allow the fault to be remedied before re-testing, and its eventual return to service.
Do not touch the equipment while conducting the test. ←←←
INSULATION TEST :
A test voltage is applied, usually 500V DC, between the Earth conductor and Live & Neutral linked together.
We are looking for a high value (>1MΩ), and results showing infinity (∞) are common.
Do not touch the equipment while conducting the test.←←←
PAT Testing and Portable Appliance Testing information
Fuse Ratings
For the convenience of users, appliance manufacturers have standardised on two plug fuse ratings- 3A & 13A and adopted appropriate flex sizes. For appliances up to 700W a 3A fuse is used, for those over 700W a 13A fuse is used.
A variety of fuse ratings (1A, 2A, 3A, 5A, 7A, 10A 13A common ratings in bold) are available.
The fuse in the plug is not fitted to protect the appliance, although in practice it often does this. Appliances are generally designed to European standards for use throughout Europe. In most countries the plug is unfused. If an appliance needs a fuse to comply with the standard it must be fitted within the appliance. The fuse in the plug protects against faults in the flex and can allow the use of a reduced csa flexible cable. This is advantageous for such appliances as electric blankets, soldering irons and Christmas tree lights, where the flexibility of a small flexible cable is desirable.
With some loads it is normal to use a slightly higher rated fuse than the normal operating current. For example on 500 W halogen floodlights it is normal to use a 5 A fuse even though a 3 A would carry the normal operating current. This is because halogen lights draw a significant surge of current at switch on as their cold resistance is far lower than their resistance at operating temperature.
The Regulations implement an EC Directive aimed at the protection of workers and the "general duties" will require the need to:
a) Make sure that equipment is suitable for the use that will be made of it.
b) Take into account the working conditions and hazards in the workplace.
c) Ensure equipment is used only for operations for which, and under conditions for which, it is suitable.
d) Ensure that equipment is maintained in an efficient state, in efficient working order and in good repair.
e) Provide equipment that conforms to EC product safety directives.
f) Plus certain other general duties and specific requirements etc.
VISUAL INSPECTION
In practice approximately 90% of all equipment defects are found during a preliminary visual inspection.
(1) The exterior of the equipment will be inspected for:
(i) physical damage.
(ii) signs of overheating
(iii) signs of ingress of liquid or foreign materials.
Particular attention will be paid to possible physical damage at accessible mains components such as switches, fuses and appliance couplers.
(2) All mains and power cords, including interconnecting cords, will be checked for physical damage. All flexible cords showing any sign of damage will be replaced
(3) Where re-wireable plugs or appliance couplers are used, their covers will be removed, and (i) terminations and cord grips will be checked for tightness.
(ii) terminations will be checked for correct polarity.
(iii) conductors will be checked for damage or loose strands.
(4) Operator accessible fuses on the outside of the equipment will be checked for correct type and rating. If the equipment manufacturer has specified a particular rating for the plug fuse, this will also be checked. If the manufacturer has not specified a fuse rating for the plug the preferred fuse size will be determined and the correct size fitted, and check that properly manufactured cartridge fuses to British Standards are used.
5) Plugs with none insulated pins will be replaced with British Standards approved Insulated ones.
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