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Mercury 5 x 20mm F15A Quick Blow Glass Fuse - 250V

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

The Mercury F15A is a 5 x 20mm quick blow glass cartridge fuse rated at 15 amps and 250 volts. The fuse uses a thin wire element sealed inside a glass tube with nickel-plated brass end caps, designed to break the circuit within milliseconds of the current exceeding the 15A threshold. Quick blow fuses react faster than slow-blow or time-delay types, making them suited to circuits where equipment should be isolated immediately on fault rather than riding through brief inrush currents.

Used in electronics, audio equipment, small appliances, power supplies and control panels where the load current runs close to or at the fuse rating under normal operation, and where a fault such as a short circuit or component failure needs to trigger instant disconnection. The 5 x 20mm format fits standard cartridge fuse holders and clips found in IEC mains inlet modules, PCB-mounted holders, and panel-mount fuse blocks.

The glass body allows visual confirmation of whether the fuse has blown — the wire element inside will show a visible break or discolouration after a fault. The nickel-plated brass end caps provide reliable contact and resist corrosion in indoor and low-humidity environments. The fuse meets IEC 60127 standards for miniature fuses, ensuring consistent breaking capacity and dimensional compatibility with holders from other manufacturers.

Frequently Asked

What's the difference between quick blow and slow blow fuses?

Quick blow fuses (also called fast-acting or F-rated) break the circuit within milliseconds of the current exceeding the rated value. Slow blow fuses (T-rated or time-delay) tolerate brief current surges before breaking, allowing motors or capacitive loads to start without nuisance blowing. The F15A is a quick blow type, so it's not suited to circuits with high inrush currents at switch-on.

Can this replace a 13A fuse?

No. Fuses must be matched to the circuit's design current and the cable rating protecting that circuit. Fitting a higher-rated fuse than specified can allow overcurrent to damage wiring or equipment before the fuse breaks. Only use a 15A fuse where the circuit design calls for 15A protection.

What does the glass construction affect?

Glass-bodied fuses allow you to see whether the internal wire element has broken. The glass itself provides no electrical function — it's purely a housing. Ceramic-bodied fuses in the same rating offer higher breaking capacity for fault currents but are opaque, so you can't visually confirm the state of the fuse without testing it.

Is it reusable after it blows?

No. Once the fuse has blown the wire element inside is severed and the fuse must be replaced. Do not attempt to bypass a blown fuse or fit a higher-rated fuse without first identifying and fixing the fault that caused the original fuse to blow.

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 F15A is a 5 x 20mm quick blow glass cartridge fuse rated at 15 amps and 250 volts. The fuse uses a thin wire element sealed inside a glass tube with nickel-plated brass end caps, designed to break the circuit within milliseconds of the current exceeding the 15A threshold. Quick blow fuses react faster than slow-blow or time-delay types, making them suited to circuits where equipment should be isolated immediately on fault rather than riding through brief inrush currents.

    Used in electronics, audio equipment, small appliances, power supplies and control panels where the load current runs close to or at the fuse rating under normal operation, and where a fault such as a short circuit or component failure needs to trigger instant disconnection. The 5 x 20mm format fits standard cartridge fuse holders and clips found in IEC mains inlet modules, PCB-mounted holders, and panel-mount fuse blocks.

    The glass body allows visual confirmation of whether the fuse has blown — the wire element inside will show a visible break or discolouration after a fault. The nickel-plated brass end caps provide reliable contact and resist corrosion in indoor and low-humidity environments. The fuse meets IEC 60127 standards for miniature fuses, ensuring consistent breaking capacity and dimensional compatibility with holders from other manufacturers.

    Frequently Asked

    What's the difference between quick blow and slow blow fuses?

    Quick blow fuses (also called fast-acting or F-rated) break the circuit within milliseconds of the current exceeding the rated value. Slow blow fuses (T-rated or time-delay) tolerate brief current surges before breaking, allowing motors or capacitive loads to start without nuisance blowing. The F15A is a quick blow type, so it's not suited to circuits with high inrush currents at switch-on.

    Can this replace a 13A fuse?

    No. Fuses must be matched to the circuit's design current and the cable rating protecting that circuit. Fitting a higher-rated fuse than specified can allow overcurrent to damage wiring or equipment before the fuse breaks. Only use a 15A fuse where the circuit design calls for 15A protection.

    What does the glass construction affect?

    Glass-bodied fuses allow you to see whether the internal wire element has broken. The glass itself provides no electrical function — it's purely a housing. Ceramic-bodied fuses in the same rating offer higher breaking capacity for fault currents but are opaque, so you can't visually confirm the state of the fuse without testing it.

    Is it reusable after it blows?

    No. Once the fuse has blown the wire element inside is severed and the fuse must be replaced. Do not attempt to bypass a blown fuse or fit a higher-rated fuse without first identifying and fixing the fault that caused the original fuse to blow.

    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.