San Francisco electricians frequently encounter fuse boxes in older buildings. While safe if properly utilized, fused electrical systems are frequently rigged to supply more power than intended. Consequently, many insurance companies charge higher rates for buildings with fuse boxes.
Given this information, how can you be sure that your fuse box is safe? You can perform a visual inspection of your fuse box to look for signs of trouble, or call a licensed, insured electrician. Before we can spot signs of trouble in a fuse box, first let's look at how fuses work.
How fuses work
Basically, a fuse cuts off electricity to a problem area by safely “blowing” and cutting the supply line.
Short circuits and other hazards increase current. This spike in current generates heat along the path of current flow and the fuse. If enough heat results, the fuse vaporizes internally, cutting the current path. Simple but effective if used properly.
Is my fuse box safe?
Start by visually inspecting your fuse box, or by calling an experienced electrician. Be careful not to touch exposed metal. During an inspection, look for three common signs of trouble: “Over-Fusing”, “Double-Lugging”, and fuse box degradation.
Larger fuses are sometimes put in the place of the smaller blown fuse, allowing more power to flow without blowing the fuse. However, this puts more strain on the wiring system than was originally intended. This is called “Over-Fusing”.
Over-fusing was a frequent cause of fires prior to the use of modern circuit breaker panels seen in most homes today. Look for larger fuses or fuses with higher amperage markings to identify potential over-fusing.
S-Type fuses and double-lugging
To prevent Over-Fusing, the National Electric Code requires licensed electricians to replace blown fuses with special tamper proof “S-Type” fuses, seen in blue on the diagram. If you don’t see S-Type fuses in your box, it could be an indication of Over-Fusing and a sign of trouble.
Another common problem is “Double-Lugging”, or connecting multiple circuits to a single fuse. This causes more blown fuses and can damage fuse boxes. Spot Double-Lugging by looking for two or more wires terminating under the same fuse. If you see this, call a qualified electrician.
Old and overloaded fuse boxes
Lastly, the fuse box itself can become corroded or degraded over time. Many electrical installations in the San Francisco bay area are over 100 years old. Moisture, mechanical damage, and the stress of heating and cooling with changes in current load can diminish the physical integrity of the entire fuse box system.
While fuse boxes are safe if used properly, they are almost always insufficient for today’s electrical needs. Whereas in the 1920’s a home might have a few lights and a fan, today they are loaded with garbage disposals, entertainment centers, toasters, and the list goes on… It’s not hard to see why fuses are being blown and the fuse box is overloaded.
Sometimes damage to a fuse box is obvious, but a licensed electrician will often spot subtle but important warning signs. These signs include corrosion on the fuse box, smoke damage, and signs of arcing on the neutral and or hot connections.
A licensed electrician can also test to make sure the load is balanced in the fuse box, and that there are good neutral and ground connections, enabling the safe and efficient flow of electricity.
Circuit breaker panels are a good investment
A good investment in your building and the safety of its occupants is a modern circuit breaker panel installed by a qualified bay area electrician. Not only will this increase the value of your structure, but will also increase safety and stop blown fuses.
Additionally, many insurance companies reduce rates significantly with the installation of a circuit breaker load center. Installing a breaker panel often pays for itself in a few years while providing you with peace of mind and a reliable power supply.
Contact us today to get a free estimate on a circuit panel and electrical service upgrade. We’re here to answer all your questions and help you find the solution you’re looking for.