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Mercury 5 x 20mm T500mA Slow Blow Fuse - Glass Cartridge

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

The Mercury T500mA is a 5 x 20mm glass cartridge fuse rated at 500mA with a slow-blow (time-delay) characteristic, designed to protect sensitive electronics from sustained overcurrent while tolerating short inrush surges. The glass body allows visual inspection of the internal wire element, and the fuse is rated at 250V AC to suit standard UK mains-derived circuits.

Used in amplifiers, control boards, LED drivers, audio equipment and low-power lighting circuits where initial switch-on current can briefly exceed the nominal operating current, the slow-blow design prevents nuisance trips during normal start-up. The 500mA rating suits circuits drawing between 200-450mA continuous load, with headroom for transient peaks up to approximately 800mA for several seconds before the element melts.

The 5 x 20mm format fits standard fuse clips and panel-mount holders found in most audio amplifiers, mixer desks, LED power supplies and control panels. The glass construction meets IEC standards for low-voltage fuses and provides a clear visual indication when the fuse has blown — the wire element separates and usually leaves scorch marks on the inside of the glass tube.

Frequently Asked

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

Slow-blow fuses tolerate brief current surges (such as capacitor inrush or motor start-up) without blowing, whereas fast-blow fuses trip immediately when current exceeds the rated value. Slow-blow fuses are preferred in audio, lighting and control circuits where start-up current can temporarily exceed the running current.

What current does the T500mA rating protect?

500mA is the nominal rating. The fuse will carry 500mA continuously without blowing, and will tolerate brief surges of approximately 800mA-1A for a few seconds. Sustained overcurrent beyond that range will cause the element to melt and break the circuit.

How do I know if the fuse has blown?

The glass body allows visual inspection. When blown, the internal wire element will be visibly broken, often with scorch marks or black residue on the inside of the glass tube. If the wire is intact and the fuse still does not conduct, test with a multimeter set to continuity mode.

Are these fuses supplied individually or in packs?

Check the product quantity selector on this page. Mercury fuses are typically sold in packs of multiple units rather than individually.

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

    The Mercury T500mA is a 5 x 20mm glass cartridge fuse rated at 500mA with a slow-blow (time-delay) characteristic, designed to protect sensitive electronics from sustained overcurrent while tolerating short inrush surges. The glass body allows visual inspection of the internal wire element, and the fuse is rated at 250V AC to suit standard UK mains-derived circuits.

    Used in amplifiers, control boards, LED drivers, audio equipment and low-power lighting circuits where initial switch-on current can briefly exceed the nominal operating current, the slow-blow design prevents nuisance trips during normal start-up. The 500mA rating suits circuits drawing between 200-450mA continuous load, with headroom for transient peaks up to approximately 800mA for several seconds before the element melts.

    The 5 x 20mm format fits standard fuse clips and panel-mount holders found in most audio amplifiers, mixer desks, LED power supplies and control panels. The glass construction meets IEC standards for low-voltage fuses and provides a clear visual indication when the fuse has blown — the wire element separates and usually leaves scorch marks on the inside of the glass tube.

    Frequently Asked

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

    Slow-blow fuses tolerate brief current surges (such as capacitor inrush or motor start-up) without blowing, whereas fast-blow fuses trip immediately when current exceeds the rated value. Slow-blow fuses are preferred in audio, lighting and control circuits where start-up current can temporarily exceed the running current.

    What current does the T500mA rating protect?

    500mA is the nominal rating. The fuse will carry 500mA continuously without blowing, and will tolerate brief surges of approximately 800mA-1A for a few seconds. Sustained overcurrent beyond that range will cause the element to melt and break the circuit.

    How do I know if the fuse has blown?

    The glass body allows visual inspection. When blown, the internal wire element will be visibly broken, often with scorch marks or black residue on the inside of the glass tube. If the wire is intact and the fuse still does not conduct, test with a multimeter set to continuity mode.

    Are these fuses supplied individually or in packs?

    Check the product quantity selector on this page. Mercury fuses are typically sold in packs of multiple units rather than individually.

    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.