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Mercury 5 x 20mm T4A Slow Blow Fuses - 250V IEC

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

The Mercury T4A is a 5 x 20mm glass slow blow fuse rated at 4A and 250V, designed to withstand short bursts of inrush current before tripping. The time-delay element inside the glass tube allows temporary current spikes during equipment startup without interrupting the circuit, while still providing overload protection once the current exceeds the 4A rating for a sustained period.

Slow blow fuses are used in audio amplifiers, lighting control equipment, motor-driven appliances and power supplies where startup current can briefly exceed normal operating current by a factor of two to five times. The 5 x 20mm form factor is a standard cartridge size that fits most panel-mount and PCB fuse holders used in consumer electronics, professional audio and stage lighting equipment.

The Mercury T4A carries IEC approval and is manufactured to comply with IEC 60127 standards for miniature fuses. The glass body allows visual inspection of the fuse element to confirm whether the fuse has blown, and the nickel-plated brass end caps provide reliable contact in fuse holders. Each fuse is marked with the rating, so the installed value can be verified without removal.

Frequently Asked

What does 'slow blow' mean?

A slow blow fuse has a time-delay element that tolerates brief current surges above the rated amperage, allowing equipment to start up without tripping the fuse. Once the current remains above the rating for a sustained period, the fuse blows and interrupts the circuit.

What's the difference between this and a fast-acting fuse?

A fast-acting fuse blows almost immediately when current exceeds the rated amperage, even for a fraction of a second. A slow blow fuse like the T4A allows temporary surges, making it suitable for equipment with high inrush current at startup.

What equipment uses 5 x 20mm fuses?

Panel-mount fuse holders in audio amplifiers, mixing desks, DMX controllers, power supplies and lighting equipment commonly use 5 x 20mm cartridge fuses. Check your equipment's manual or the existing fuse to confirm size and rating before replacement.

Can this be used in place of a fast-acting 4A fuse?

Only if the equipment specifies a slow blow or time-delay fuse. Using a slow blow fuse in a circuit designed for fast-acting protection may delay the fuse's response to a fault condition, potentially allowing damage to components.

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 T4A is a 5 x 20mm glass slow blow fuse rated at 4A and 250V, designed to withstand short bursts of inrush current before tripping. The time-delay element inside the glass tube allows temporary current spikes during equipment startup without interrupting the circuit, while still providing overload protection once the current exceeds the 4A rating for a sustained period.

    Slow blow fuses are used in audio amplifiers, lighting control equipment, motor-driven appliances and power supplies where startup current can briefly exceed normal operating current by a factor of two to five times. The 5 x 20mm form factor is a standard cartridge size that fits most panel-mount and PCB fuse holders used in consumer electronics, professional audio and stage lighting equipment.

    The Mercury T4A carries IEC approval and is manufactured to comply with IEC 60127 standards for miniature fuses. The glass body allows visual inspection of the fuse element to confirm whether the fuse has blown, and the nickel-plated brass end caps provide reliable contact in fuse holders. Each fuse is marked with the rating, so the installed value can be verified without removal.

    Frequently Asked

    What does 'slow blow' mean?

    A slow blow fuse has a time-delay element that tolerates brief current surges above the rated amperage, allowing equipment to start up without tripping the fuse. Once the current remains above the rating for a sustained period, the fuse blows and interrupts the circuit.

    What's the difference between this and a fast-acting fuse?

    A fast-acting fuse blows almost immediately when current exceeds the rated amperage, even for a fraction of a second. A slow blow fuse like the T4A allows temporary surges, making it suitable for equipment with high inrush current at startup.

    What equipment uses 5 x 20mm fuses?

    Panel-mount fuse holders in audio amplifiers, mixing desks, DMX controllers, power supplies and lighting equipment commonly use 5 x 20mm cartridge fuses. Check your equipment's manual or the existing fuse to confirm size and rating before replacement.

    Can this be used in place of a fast-acting 4A fuse?

    Only if the equipment specifies a slow blow or time-delay fuse. Using a slow blow fuse in a circuit designed for fast-acting protection may delay the fuse's response to a fault condition, potentially allowing damage to components.

    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.