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Mercury T800mA 5 x 20mm Slow Blow Fuse - 250V Time Delay

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

The Mercury T800mA is a 5 x 20mm glass cartridge fuse with a time-delay (slow blow) element, rated at 800mA breaking capacity and 250V maximum voltage. The time-delay characteristic allows the fuse to tolerate brief current surges during device startup or motor inrush without blowing, while still protecting against sustained overcurrent faults.

Designed for low-current electronics, audio equipment, control panels and instruments where startup current can temporarily exceed the steady-state operating current, the slow blow design prevents nuisance tripping during normal operation. The 5 x 20mm glass cartridge format fits standard panel-mount and PCB-mount fuse holders, with nickel-plated end caps providing reliable contact and corrosion resistance.

The fuse is built to IEC standards and carries the appropriate approval markings for use in consumer and industrial equipment sold in the UK and EU. The 800mA rating sits between the more common 500mA and 1A values, making it suitable for equipment drawing steady currents in the 400-600mA range where a 500mA fast-blow fuse would trip prematurely but a 1A fuse would provide insufficient protection.

Frequently Asked

What is a slow blow fuse and when is it needed?

A slow blow (time-delay) fuse tolerates brief current surges without blowing, typically for 10-100 milliseconds depending on the surge magnitude. This prevents the fuse from tripping during motor startup, transformer inrush, or capacitor charging events in equipment that has a higher startup current than running current.

What equipment uses 800mA fuses?

Common applications include audio mixers, guitar amplifiers, control panels, instrumentation, LED drivers and low-power DC supplies. The 800mA rating protects circuits drawing steady currents between 400-600mA where a 500mA fuse is too sensitive and a 1A fuse provides inadequate protection.

Is this fuse reusable after it blows?

No. Glass cartridge fuses are single-use consumables. Once the internal element melts under fault current, the fuse must be replaced. Always replace a blown fuse with the same rating and type — do not substitute a higher-rated or fast-blow fuse.

What is the physical size?

The fuse measures 5mm diameter by 20mm length, fitting standard 5 x 20mm fuse holders. The glass body is transparent, allowing visual inspection of the internal wire element to confirm whether the fuse has blown.

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 T800mA is a 5 x 20mm glass cartridge fuse with a time-delay (slow blow) element, rated at 800mA breaking capacity and 250V maximum voltage. The time-delay characteristic allows the fuse to tolerate brief current surges during device startup or motor inrush without blowing, while still protecting against sustained overcurrent faults.

    Designed for low-current electronics, audio equipment, control panels and instruments where startup current can temporarily exceed the steady-state operating current, the slow blow design prevents nuisance tripping during normal operation. The 5 x 20mm glass cartridge format fits standard panel-mount and PCB-mount fuse holders, with nickel-plated end caps providing reliable contact and corrosion resistance.

    The fuse is built to IEC standards and carries the appropriate approval markings for use in consumer and industrial equipment sold in the UK and EU. The 800mA rating sits between the more common 500mA and 1A values, making it suitable for equipment drawing steady currents in the 400-600mA range where a 500mA fast-blow fuse would trip prematurely but a 1A fuse would provide insufficient protection.

    Frequently Asked

    What is a slow blow fuse and when is it needed?

    A slow blow (time-delay) fuse tolerates brief current surges without blowing, typically for 10-100 milliseconds depending on the surge magnitude. This prevents the fuse from tripping during motor startup, transformer inrush, or capacitor charging events in equipment that has a higher startup current than running current.

    What equipment uses 800mA fuses?

    Common applications include audio mixers, guitar amplifiers, control panels, instrumentation, LED drivers and low-power DC supplies. The 800mA rating protects circuits drawing steady currents between 400-600mA where a 500mA fuse is too sensitive and a 1A fuse provides inadequate protection.

    Is this fuse reusable after it blows?

    No. Glass cartridge fuses are single-use consumables. Once the internal element melts under fault current, the fuse must be replaced. Always replace a blown fuse with the same rating and type — do not substitute a higher-rated or fast-blow fuse.

    What is the physical size?

    The fuse measures 5mm diameter by 20mm length, fitting standard 5 x 20mm fuse holders. The glass body is transparent, allowing visual inspection of the internal wire element to confirm whether the fuse has blown.

    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.