Tanning Bed Fuse Keeps Blowing: Where to Look Before You Replace It Again

A blown fuse costs you a session and a trip to the parts drawer. A fuse that blows again the next day costs you the room, because now you are feeding fuses into a fault instead of fixing it. A fuse opened because something behind it pulled more current than it should, and until you find that something, the new fuse is going the same way. Here is how to read the old fuse and where to look.

Where the fuses are and what the markings mean

A tanning bed usually has more than one fuse. A main fuse near the power inlet or in the power box protects the whole bed. Smaller fuses protect the control board, the timer interface or the fan circuit, and some beds fuse each ballast bank. Before you pull one, write down what is printed on the end cap:

• Amperage, the number followed by A.
• Voltage rating. Must be at or above the circuit voltage. 250 volts is normal here.
• Type. F is fast-acting and opens almost instantly. T is time-delay, or slow-blow, and tolerates the brief surge when lamps strike. Ballast circuits almost always use time-delay. Control boards usually use fast-acting.
• Size. Glass cartridge fuses come in a few lengths, and the wrong one will not seat.

Replace like for like on all four. A fast-acting fuse in a time-delay slot blows on every start and sends you chasing a fault that is not there. The common fuses and holders are on our electrical parts page.

1. Read the dead fuse

The old fuse is your first clue, so do not throw it out. Hold it to the light. A dark splash inside the glass, a silvered coating or a shattered element means it opened on a very high current: a short, a component or wire that failed hard. A small clean gap in the element, or an element that sagged and parted, means a moderate overload or plain age. One clean break after years in service can be fatigue. Two is an overload you have to find.

2. Note when it blows

Timing narrows it down the same way it does with a breaker.

• Blows the instant the session starts. A short, or the wrong fuse type. If a correct time-delay fuse blows at lamp strike, something is shorted, usually a ballast, a capacitor or a lamp holder.
• Blows after the bed has run a while. An overload that builds with heat. A ballast with failing windings draws more as it warms. A fan with dry bearings pulls more. A loose connection heats and its resistance climbs.
• Blows at random, sometimes weeks apart. An intermittent. A wire that touches the frame when the canopy moves, a cracked lamp holder that arcs when the bed warms and expands, or moisture that comes and goes.

3. Ballast and capacitor

With the power off and the bed unplugged, open the ballast compartment and look before you test. A failed ballast usually shows it: discoloration, a bulged or split case, tar at the seams, a sharp burnt smell. Feel the cases after a run, once unplugged. The one much hotter than its neighbors is the one to test. Magnetic ballast beds also carry a power factor capacitor, and a shorted capacitor blows fuses at startup every time. A bulged top or oily residue at the terminals gives it away. Capacitors can hold a charge after power is off, so do not touch the terminals. Our ballasts page covers what we stock.

4. Lamp holders and the lamp swap

Lamp holders take a beating from every lamp change, every lamp seated crooked and every drop of lotion that finds its way in. A holder that has arced shows a dark track burned across the plastic or a pitted, loose pin. That track conducts, and it keeps arcing until it melts or blows the fuse. Pull each lamp and check the holder with a flashlight. Replace any that are cracked, discolored or loose. While the lamps are out, do a swap test. A lamp with a shorted end can take a fuse with it, and moving lamps to see if the problem follows one is a five minute test. Holders are on our lamps page. A starter that has failed shorted is another startup fuse killer, and those are on our starters page.

5. Wiring and fans

Look for a wire rubbed through at a sharp edge, a hinge or a fan housing, and for insulation gone brittle from years beside a hot ballast. Spin each fan by hand with the power off. One that is stiff or grinds has bearings on the way out, and a seized fan motor is a dead short as far as the fuse is concerned. Fans are on our fans and cooling page.

When to call

Replace a fuse once, like for like, if it has a clean break and the bed has run fine for years. If it blows again, if the first shows the dark splash of a short, if you find a burnt ballast, bulged capacitor or arced lamp holder, or if you smell anything hot, stop. Those repairs are on the high voltage side and they are ours. On the call we ask what the dead fuse looks like, when it blows, and what you saw in the ballast compartment, and that usually tells us what to put on the truck. If the breaker trips too, read our guide on a bed that keeps tripping the breaker, since the two often share a cause.

Safety

Power off and unplug the bed before you touch a fuse holder or open any panel. The ballast compartment carries high voltage, and capacitors in magnetic ballast beds can hold a charge after the power is off. Never replace a fuse with a higher rating, a different type, or anything that is not a fuse. Never bypass a fuse holder, a safety switch or a thermal cutoff to get through the day. A melted or discolored fuse holder gets replaced with the fuse, and the cause gets found before the bed runs again.

Related guides

• Tanning bed keeps tripping the breaker: what it usually is
• Flickering or dead lamps: ballast, starter or lamp?
• Tanning bed won't turn on: the salon owner's checklist
• Tanning bed parts we stock