Free Delivery on all orders over £99*

Mercury 5 x 20mm T5A Slow Blow Fuses - 250V

£149
The RRP is the manufacturer's recommended retail price of the item.
Limited Stock
We are an Independent UK Company
Price match. Found it cheaper? Contact us
Trade Discount Available
Description

The Mercury T5A is a 5 x 20mm slow blow fuse rated at 5A and 250V, built to IEC specifications. The glass tube construction houses a time-delay fuse wire that tolerates brief inrush current surges without blowing, making it suitable for appliances and equipment that draw higher current on startup before settling to their rated load.

Slow blow fuses are used in small motors, transformers, power supplies, audio amplifiers and other devices where the startup current temporarily exceeds the running current. The 5 x 20mm format fits standard fuse holders in consumer electronics, lab equipment, legacy hi-fi systems and industrial control panels. The 5A rating protects circuits drawing up to 5 amps continuous current while tolerating short-duration spikes above that threshold.

Each fuse consists of a clear glass tube with nickel-plated brass end caps. The internal wire is visible through the glass, allowing quick visual inspection to confirm whether the fuse has blown. The 250V capacity covers both UK mains (230V) and lower-voltage DC circuits in automotive and marine applications.

Frequently Asked

What does 'slow blow' mean?

A slow blow (or time-delay) fuse tolerates brief current surges above its rating before blowing. This prevents nuisance blowing during equipment startup when motors, transformers or capacitors draw higher inrush current for a few milliseconds or seconds.

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

Fast blow fuses respond immediately to any overcurrent condition. Slow blow fuses wait, allowing short-duration surges to pass before opening the circuit. For equipment with high startup current, a slow blow fuse prevents the need to replace fuses every time the device is switched on.

Can I use this in mains voltage equipment?

Yes. The 250V rating covers UK mains voltage (230V). However, always confirm the fuse type and rating specified by the equipment manufacturer before fitting a replacement — using the wrong rating or type can create a fire or shock hazard.

How do I know if the fuse has blown?

The clear glass tube allows visual inspection. A blown fuse shows a broken or discoloured wire inside the tube, often with black soot deposits on the glass. An intact fuse shows a continuous wire running between the two end caps.

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.

See it lit, in person

Lighting looks different in a real room. Come and see our range at our showrooms in Birmingham, Hong Kong and Dubai, or talk to our design team wherever you are.

Niori lighting showroom trailer video with closeups of alabaster lighting

Why Niori

Over 20 years lighting homes worldwide

We are a specialist lighting and mirror retailer with showrooms in Birmingham, Hong Kong and Dubai, shipping to customers around the world. Our own design team is here to help, from first idea to final fitting.

Genuine products

An authorised stockist

Every product arrives brand new with the full manufacturer warranty. Found it cheaper elsewhere? Ask us about a price match.

Ordering with us

Free delivery over £99

Free delivery on orders over £99, in the UK and worldwide. Easy returns within 14 days, subject to our returns policy. Full manufacturer warranty included.

Design help

Not sure what you need?

Our design team can help you plan your lighting, share photos and videos of stock, and send samples worldwide. Book a showroom visit in Birmingham, Hong Kong or Dubai, or ask about our lighting design service.

You Might Also Like

Recommended For You

    Our Reviews

    From first click to final installation, our customers share how Niori lights up their spaces. Read their words and envision what’s possible for yours.

    Featured Projects

    Step into our portfolio and see how we transform homes, restaurants, and commercial spaces and more, worldwide. Click here for a closer look at our latest projects.

    Description

    The Mercury T5A is a 5 x 20mm slow blow fuse rated at 5A and 250V, built to IEC specifications. The glass tube construction houses a time-delay fuse wire that tolerates brief inrush current surges without blowing, making it suitable for appliances and equipment that draw higher current on startup before settling to their rated load.

    Slow blow fuses are used in small motors, transformers, power supplies, audio amplifiers and other devices where the startup current temporarily exceeds the running current. The 5 x 20mm format fits standard fuse holders in consumer electronics, lab equipment, legacy hi-fi systems and industrial control panels. The 5A rating protects circuits drawing up to 5 amps continuous current while tolerating short-duration spikes above that threshold.

    Each fuse consists of a clear glass tube with nickel-plated brass end caps. The internal wire is visible through the glass, allowing quick visual inspection to confirm whether the fuse has blown. The 250V capacity covers both UK mains (230V) and lower-voltage DC circuits in automotive and marine applications.

    Frequently Asked

    What does 'slow blow' mean?

    A slow blow (or time-delay) fuse tolerates brief current surges above its rating before blowing. This prevents nuisance blowing during equipment startup when motors, transformers or capacitors draw higher inrush current for a few milliseconds or seconds.

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

    Fast blow fuses respond immediately to any overcurrent condition. Slow blow fuses wait, allowing short-duration surges to pass before opening the circuit. For equipment with high startup current, a slow blow fuse prevents the need to replace fuses every time the device is switched on.

    Can I use this in mains voltage equipment?

    Yes. The 250V rating covers UK mains voltage (230V). However, always confirm the fuse type and rating specified by the equipment manufacturer before fitting a replacement — using the wrong rating or type can create a fire or shock hazard.

    How do I know if the fuse has blown?

    The clear glass tube allows visual inspection. A blown fuse shows a broken or discoloured wire inside the tube, often with black soot deposits on the glass. An intact fuse shows a continuous wire running between the two end caps.

    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.