Monday, January 17, 2011

Surge Protectors

There are two basic types of surge protectors: a portable protector is intended to be plugged into the campground utility box, while a hard-wired protector is permanently wired inside the RV and is always ON, so so speak.

It's very important to understand what a surge protector does; the name can be misleading because the unit does far more than simply protect against a "power surge", as the name suggests. The unit is actually a "power line monitor", preventing power spikes and low power situations from harming your rig's electrical system and any equipment plugged into it.

A hard-wired system is more convenient - nothing to deploy before plugging in to shore power, and no need to worry about theft. Additionally, it can be wired so that it protects the coach when the generator is being used. The hard-wired models are generally less expensive than the portable versions.

With a portable unit, before the RV is connected to the power supply, the unit is plugged in to the campground pedestal and it checks for improper wiring; reversed polarity and improper ground are pretty common problems. After the initial check proves the supply is safe, the RV is connected to the power line monitor, and the monitor connected to the supply. The unit then continually monitors the power supply going into the RV. If the power supply provides too-low or too-high voltage for a certain period of time (the amount of time is set by the manufacturer, I believe), the monitor shuts off power to the RV. It re-sets itself and delivers power when the situation of too-low or too-high voltage is resolved.

A hard-wired protector does pretty much the same thing. As soon as you plug the coach into shore power, the protector goes through a check of the circuit and only after it is satisfied that all is well does it allow power through it to the AC panel.

There are two major manufacturers, Surge Guard and Progressive.

Surge Guard is a product of TRC, Inc. You can learn more at A Google Product search shows plenty of suppliers.

Progressive Industries makes a similar unit, the EMS HW 30C, that appears to offer some advantages over the Surge Guard. The Progressive's monitor panel offers quite a bit more useful information than the SurgeGuard's simple "go/no-go" LEDs. Quoting Progressive's description, the display shows "voltage, current, frequency, error codes, and previous errors. Each reading is displayed for 2 seconds."

Installation of a hard-wired surge protector can be accomplished by the average LD owner. The biggest caution: be sure you cut all power sources to the rig before you start the process.

There are two FAQ articles on installing a hard-wired surge protector. One describes the process of putting a Progressive Industries model EMS-HW30C in a 2001 RB, wired so as to protect shore-power only. The second article deals with the installation of a Surge Guard Model 34520 in a 2005 RB so as to protect both shore and generator power sources.

Note: Progressive Industries models can also be wired to protect from all power sources.

In addition to protecting against surges, the EMS HW 30C protects against several other electrical conditions that can damage your system/appliances (high/low voltage, miswired pedestals including open grounds, open neutrals, hot grounds). The hard-wired version, doesn’t "walk off" or get accidentally left behind, and you never have to remember to put it in-line.

The surge protector should protect both shore power and the generator, as if the generator isn’t running well, it can cause the same damage to your appliances that bad shore power can. However, installing the surge protector so that it protects both costs more, both in terms of time as well as installation material.

Installing a Progressive Industries hard-wired 30 amp EMS/surge guard, to protect both shore power and the generator costs between $500 and $600.

Contributors: JC Taylor, Andy Baird, WxToad, Delta Mike
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