RV Lightning Strike… When will it happen to you?

Over the years of travel, you may have experienced, or know someone that has experienced, their RV getting directly or indirectly hit by a lightning strike.

Indirect hits occur when the RV park is directly hit or the local utility power lines that feeds the park results in a high transient voltage surge entering into the RV via the power hookup or even as transmitted (radiated magnetic) energy in the air if it is close enough.

This phenomenon tends to be more prevalent when out boondocking in open plains due to the greater exposure. There are many opinions regarding the do’s and don’ts of how to protect against lightning strike and this blog article is meant to help inform on a possible solution to help protect equipment and to share ideas.

If a RV is hit directly with a lightning strike it is usually very catastrophic taking out most of the electronics, affecting the electrical equipment and sometimes even starting a fire or tragically sometimes a loss of life. A direct lightning strike is something that is difficult to avoid or protect against. If the RV is well grounded and the electrical system is grounded accordingly there could be some hope for salvation as the metal shell acts as a shield to shut the energy to ground.

Luckily direct strikes are very rare but nearby indirect strikes are very common which will still result in equipment failures. The energy of the lightning bolt pulse is so strong that it cause direct damage to equipment (such as the TV, microwave, sound system, inverters, etc). Antennas, any type of mast structure, awnings and satellite dishes attached to the RV will also attract the lightning radiated magnetic energy or the actual bolts.

There is a solution that is available for RV’s to assist in greatly reducing the damaging effects of indirect lightning strikes to their onboard equipment. This can be very valuable when out camping in areas where technical support or equipment replacement becomes extremely difficult and costly. The addition of a simple, maintenance free, Surge Protection Device (SPD) connected into the electrical system will help clamp is high voltage transients from getting to the equipment.

How Lightning invades your RV

The basics of a lightning strike are as follows: the lightning strikes in the immediate area causing a high voltage spike induced into electrical wires resulting in high-voltage transient which feeds into the electronic equipment. The lightning transient will typically make its way in through the grounding system and not through the nominal equipment feed voltage as one would think. Most professionally manufactured equipment has the ability to withstand over 2000 V of isolation( frame to ground). Installing a surge protection device will clamp this high-voltage spike protecting the valuable equipment on board.

How does it work?

The suppressor device sits across the electrical circuit (like the 12VDC & RV ground wires that connect to the inverter, or the AC panel). When the transient voltage rises above its clamping level, it begins to turn on absorbing the lightning energy pulse thereby reducing the high-voltage exposed to the equipment. The energy is absorbed into the suppressor and circuit wiring. If the lightning strike is excessive, it could overpower the suppressor causing it to fail (sacrificial lamb). The SPD can provide a good insurance policy of equipment protection especially on indirect lightning strikes. The attached graph (courtesy of MidNite Solar) shows the clamping voltage for their three different SPD models which clamp the voltage well below the 2000V which most pieces of equipment are designed to handle.

Surge Suppressor Types

There are several suppressor design types in the marketplace. Some utilize a “spark gap” topology which is usually enclosed in a sealed container surrounded by sand. These devices are for catastrophic conditions and do not have the consistent clamping capability found in “active” devices. Active devices use components, such as a metal oxide varistor (MOV’s), which is a semiconductor device. The varistor will turn on at a specific voltage placing a “load” on the circuit which results in the clamping of the transient pulse. If the voltage continues to rise (due to excessive energy because it’s a big transient) it becomes more conductive increasing clamping. In this example (active suppressors), are more predictable because of their predefined voltages and can absorb proportionally the energy pulse unless, of course, a catastrophic energy pulse is present forcing the failure of the SPD. In short these active devices are able to protect the equipment more effectively and reliably, and can do so without destroying themselves (most of the time).

Where the SPD’s work

On DC circuits, such as a 12 V system, the SPD would be hooked onto the RV ground and across the DC battery system, preferably at or near the location of the equipment feed. Several suppressors might be necessary on a typical RV installation based on the equipment, distance and circuits. Solar PV systems can receive a nearby lightning strike spike channeling it directly into the onboard equipment. eMarine recommends the installation of suppressors (SPD) on either input / output circuits of these devices to protect the regulators as well as limiting the pulse from entering other on-board equipment.

AC circuits (120 VAC) on-board are also susceptible to surges and transients. High-voltage transients entering through shore power can affect the battery charging systems, inverters, TV’s, microwave oven, computers and other electronics. The SPD can be used to protect from these conditions by connecting one on the input side of the distribution panel. Besides protecting against transients from indirect lightning strikes the SPD will also help to protect against transients that may be generated from the camp ground park power which is also a common occurrence, especially when connected at the far end of the feed from their main power panel.

eMarine is pleased to recommend the MidNite Solar SPD suppressors because they offer an active design housed in a 4X rated (water rated) clear enclosure making them superb for installations. They are available in 3 voltage ratings (115, 300 & 600). Additionally there is a blue indicator LED showing it is actively monitoring and protecting. The SPD’s come with a 5 year warranty and can be factory rebuilt, if necessary, making them a smart investment. Special note that these are easy to install, nothing to set up or maintain.