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Mercury 5 x 20mm F500mA Quick Blow Fuses - 250V

£149
The RRP is the manufacturer's recommended retail price of the item.
Limited Stock
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Description

Mercury F500mA quick blow fuses are 5 x 20mm glass cartridge fuses rated at 500mA (0.5A) on 250V circuits, designed to open the circuit rapidly when the current exceeds the rated threshold. The fast-blow characteristic means the fuse element melts and breaks the circuit within milliseconds of an overload or short-circuit event, protecting sensitive low-power electronics from damage.

These fuses suit applications where immediate fault clearance is required rather than delayed protection. Common uses include power supplies for audio equipment, LED drivers, small transformers, appliance control boards, test equipment and battery chargers operating below 500mA. The 5 x 20mm cartridge format fits standard inline fuse holders and PCB-mounted clips used across consumer electronics and light commercial equipment.

The glass body allows visual inspection of the fuse element — a blown fuse shows a broken or blackened wire inside the tube. The nickel-plated brass end caps provide good conductivity and resist corrosion in typical indoor environments. IEC approval confirms compliance with international safety standards for fuse construction and performance characteristics.

Frequently Asked

What does F500mA mean?

F denotes a fast-blow or quick-acting fuse, meaning it responds within milliseconds to overcurrent. 500mA is the current rating — the fuse will blow if the circuit draws more than 500 milliamps continuously or experiences a short-circuit spike.

What's the difference between fast-blow and slow-blow fuses?

Fast-blow fuses open the circuit immediately when current exceeds the rating, making them suitable for electronics that need instant protection. Slow-blow fuses tolerate brief current surges (such as motor start-up or transformer inrush) before blowing, and are not suitable for the same applications as these F500mA fuses.

Can these be used in mains appliances?

Yes, the 250V rating covers UK 230V mains circuits. However, the 500mA current rating is very low — these fuses are for small power supplies, control circuits and low-power electronics inside appliances, not for mains inlet protection on larger loads.

Are these sold individually or in packs?

Check the product quantity field on this page for the pack size. Mercury fuses are typically supplied in packs of 10 or more.

Shipping & Returns

Delivery UK delivery is £14.99, and delivery is free on all orders of £99 or more, in the UK and internationally.

Returns If you change your mind, you have 14 days from delivery to tell us, and a further 14 days to send the goods back. Return postage for a change-of-mind return is paid by you. Change-of-mind returns are subject to an inspection and handling deduction. See our full returns policy.

To arrange a return, call us on 020 8149 5199 or use our contact page.

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    Description

    Mercury F500mA quick blow fuses are 5 x 20mm glass cartridge fuses rated at 500mA (0.5A) on 250V circuits, designed to open the circuit rapidly when the current exceeds the rated threshold. The fast-blow characteristic means the fuse element melts and breaks the circuit within milliseconds of an overload or short-circuit event, protecting sensitive low-power electronics from damage.

    These fuses suit applications where immediate fault clearance is required rather than delayed protection. Common uses include power supplies for audio equipment, LED drivers, small transformers, appliance control boards, test equipment and battery chargers operating below 500mA. The 5 x 20mm cartridge format fits standard inline fuse holders and PCB-mounted clips used across consumer electronics and light commercial equipment.

    The glass body allows visual inspection of the fuse element — a blown fuse shows a broken or blackened wire inside the tube. The nickel-plated brass end caps provide good conductivity and resist corrosion in typical indoor environments. IEC approval confirms compliance with international safety standards for fuse construction and performance characteristics.

    Frequently Asked

    What does F500mA mean?

    F denotes a fast-blow or quick-acting fuse, meaning it responds within milliseconds to overcurrent. 500mA is the current rating — the fuse will blow if the circuit draws more than 500 milliamps continuously or experiences a short-circuit spike.

    What's the difference between fast-blow and slow-blow fuses?

    Fast-blow fuses open the circuit immediately when current exceeds the rating, making them suitable for electronics that need instant protection. Slow-blow fuses tolerate brief current surges (such as motor start-up or transformer inrush) before blowing, and are not suitable for the same applications as these F500mA fuses.

    Can these be used in mains appliances?

    Yes, the 250V rating covers UK 230V mains circuits. However, the 500mA current rating is very low — these fuses are for small power supplies, control circuits and low-power electronics inside appliances, not for mains inlet protection on larger loads.

    Are these sold individually or in packs?

    Check the product quantity field on this page for the pack size. Mercury fuses are typically supplied in packs of 10 or more.

    Shipping & Returns

    Delivery UK delivery is £14.99, and delivery is free on all orders of £99 or more, in the UK and internationally.

    Returns If you change your mind, you have 14 days from delivery to tell us, and a further 14 days to send the goods back. Return postage for a change-of-mind return is paid by you. Change-of-mind returns are subject to an inspection and handling deduction. See our full returns policy.

    To arrange a return, call us on 020 8149 5199 or use our contact page.