Wednesday, February 23, 2011

5 amp fuse - cowboy electrician detector

Most home appliances do not require more than 5 amps of electrical 'draw'.

However hairdryers are a notable exception. Hairdryers which have a rating of more than 1200 watts will need a fuse larger than 5 amps.
So if your hairdryer says 'Salon rated 1800 watts' or 'Salon quality 2000 watt AC motor' then you best throw a 13 amp fuse in that plug.

Other appliances that might require 13 amps, are things that involve a large physical motor, perhaps a washing machine, or a high powered vacuum cleaner.

An industrial heater or a spin dryer might require that sort of 'draw' when in 'high heat' mode.

What hairdryers will run okay on a 5 amp fuse? The smaller travel hairdryers or something small / light which you have given your daughter, may well be rated 1200 watts or less (for that a 5 amp will do fine)

Old televisions that are more than 3 years old but less than 10 years old, do NOT require a large 'draw', to power the emitter at the back of the Cathode Ray setup. Newer televisions are often better again, and can usually be fitted with 5 amp fuses (see next section)

Power washers that claim to be powerful enough to clean outside concrete, with a blast of water ... yep that will likely be more than 5 amps worth.

Your laptop is likely to require less than 1 amp (more details toward end of article)


What in my home should be fitted with a 3 amp or 5 amp fuse?:

Bedside lamps and reasonably modern oil heaters, should not require more than 5 amps.

For some a 3 amp fuse will be sufficient (check the booklet)

( Readers from outside the UK, may have a different granularity with regard to plug fuses, or adopt a 'one fits all' approach )

LED Televisions (even up to 32 inches) rarely require more than 1 amp!!

Older televisions (we have a 28 inch from 2005) require less than 3 amps mostly.
( The Panasonic 28DTX1 in the link above uses < 1 amp and 90-120 watts)

Look on the back of the Television and read off what it says if you are unsure.
( A good television from a reputable manufacturer, should have the Volts and Amps indicated on the rear. )

Failing that a decent Electricity monitor can tell you right away what the Television is using.


The Handyman versus the Electrician:

A reputable Electrician in the UK should never be without a range of fuses (3 amp, 5 amp, and 13 amp), and should fit appropriate for the equipment.

If you use an Electrician and s/he fits a 13 amp fuse to a 5 amp rated device, then you should ask yourself "Is this Electrician lazy or irresponsible?"


Why is this important?
As electrical devices get older they sometimes become less reliable and malfunction. The first indication might well be a warm cable or a blown fuse.

A device fitted with the correct rated fuse, will possibly indicate it's malfunction to you earlier.

( I do not own a pair of hair straighteners, however if I did, and they were rated at 4 amps, but regularly tripped a properly fitted 5 amp fuse, then I would certainly want to either replace them, or have an electrician do a safety check. )


Elderly relatives and Electrical safety:

There are various reasons why the Elderly are considered for 'priority home checks' by the Fire Department. Those reasons might well be communicated to you if you ask.

If you are visiting an Elderly relative, then take the time to help out with replacing old equipment, or enquiring about Electrical items that have seen better days.

In particular it takes only minutes to check the fuse ratings for those items and to flag up any 13 amp fuses you see.

Did the handyman fit them? Does your great Aunt or Grandfather have a ready supply of fuses, or did they just buy a pack of 13 amp and use them whatever?

A four pack of each should do, and will cost you very little from the local store.
Keep them together and mark the bag so they are conveniently found when needed.


If the device was overrated (fitted with a 13 amp fuse), then correct things and mark the plug to help in future.


This 750 watt Oil Filled (Mini) Radiator I own 'draws' 2.88 amps.

Probably a 3 amp fuse would have done, however there would be almost no tolerance there. Giving a 2.88 amp device some headroom up to 5 amps is probably a lot safer still than fitting a 13 amp fuse.


Laptop peak usage - expect your laptop to use no more than 1 amp:

If your laptop is fitted with a 13 amp plug, then I am pretty sure this fuse can be replaced with a lower rated fuse (check your laptop booklet in the section 'specification' if unsure)

Measured at the plug using an energy monitor, here are examples based on my Dell Inspiron 15 inch laptop:

  • Before boot cycle startup 0.02 amps
  • Normal usage 0.234 amps
  • Watching pre-recorded TV online (BBC iPlayer) 0.283 amps
  • Normal usage with cdrom drive spinning 0.318 amps
So that Dell Inspiron 1525 uses between a quarter to half of 1 watt and no more.

Worth a check what is in the plug at the moment:


...which is overrated as 3 amps is easily sufficient for my laptop, so a quick replacement is worth my time.





So now the laptop which draws half an amp (max), is fitted with a properly rated fuse (3 amp fuse).



Notes and further reading:

Do check the booklet when you purchase a new device.
That Oil Filled Radiator which draws 2.88 amps, came fitted with a 13 amp fuse!


A proper rating of fuse in the plug should help avoid the cable or device warming excessively in the case of older devices / malfunction.
This should make you feel safer in your home knowing that you have taken a practical step towards a known fire safety issue.
Some Electrical devices have an 'internal fuse' which is designed to protect the internal electronic circuitry.

Even with an internal fuse present, it still makes sense to stop the cable becoming excessively warm. This is particularly important if you are the type to hide cables, perhaps just under the edge of a rug or concealed at the carpet edge

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