Don't overload your power strip!
Your computer, home entertainment system, microwave and any other electronic devices are under attack every day. These attacks may be silent but they can be destructive. The enemy -- power surges.
Power strips, surge protectors, conditioners and battery backed uninterruptable power supplies are some of the commercially available ways to power your electronics. Whether you are just looking to add more outlets, add a layer of protection between you equipment and the wild world outside or keep things running even in a blackout. There are a few things about each of these that you should know.
These add extra outlets but little more than that. The standard power strip is just a glorified extension cord with multiple outlets and an on/off switch. They provide little or no protection against power spikes, brownouts, blackouts or noise. The do not cost much but they do not do much either. One cautionary note on power strips. It is not advisable to plug one power strip into another power strip. “Daisy Chaining” power strips can add too many outlets to a single circuit and cause overheating. Fire Marshals tend to frown on this type of layout.
Sometimes called Surge Suppressors or Transient Voltage Surge Suppressor's, (TVSSs) fall into two basic categories.
Service entrance solutions protect everything in the building including lights, motors, outlets, switches and other hardwired devices that cannot be plugged into a point-of-use protector. Since these usually require a trained professional to install we will focus on the point-of-use devices in this edition of the newsletter.
- Service entrance surge protection
- Point-of-use surge protection.
Even if you do have a service entrance surge protector the point-of-use protectors are still needed for two reasons.
- Not all surges are from the incoming utility line. Some are generated within the building.
- A good quality point-of-use protector usually has the ability to reduce surges to lower levels than most service entrance protectors.
In addition to providing extra outlet space surge protectors also offer protections against power spikes. But this doesn't last forever. You should plan to replace most MOV type surge protectors every three to five years. What is an MOV? I'll explain that later in this article.
I hope he has a surge protector!
MOV surge protectors are designed to sacrifice themselves for the equipment they protect. After one big surge or several smaller surges the device will no longer protect your electronics from surges. However most models will still conduct electricity without providing any protection.
Some things you should consider when looking for a new surge protector.
- Purchase only devices that have been tested to UL 1449, 2nd Edition.
- Purchase only devices that have thermal fuse protection.
- Purchase only devices with a clamping voltage of no more than 400 volts, a rating of 330 volts is preferred. This is the amount of voltage that will pass through the device and on to your electronics during a 6000 volt surge so less is better. (Most homes will never see a surge anywhere near 6000 volts.)
- Purchase only devices with protection on all three circuits Line to Neutral (L-N), Line to Ground (L-G), and Neutral to Ground (N-G).
- Purchase only devices with a working indicator light. The indicator lights that will signify if there are any problems with the protection. Be sure the device you buy has this feature. In most cases, if the surge protection capabilities are destroyed, the device will still conduct electricity. The indicator lights are a way to check to make sure the device is still protecting. Some surge protectors have an auto-shutoff feature that prevents any power output once the device is no longer able to protect against surges.
- Remember, power surges can enter through the telephone or coax lines too. Look for a device with telephone and coax cable jacks for protection of those lines if the item being protected has those types of hookups.
- Look for a device with a Ground Wire Indicator Light. A surge protector with a light that will indicate whether or not the outlet it is being plugged into is properly grounded is a convenient feature. Proper grounding is required for the surge protection device to work.
- Look for a device with a good warranty from an established manufacturer with a good reputation. Their warranty should cover any damage to the equipment that is connected through their surge protection device. But remember that just because the warranty exists doesn't mean that you'll ever see a dime from it.
- Look for a device with the highest joules rating available. The joule rating indicates how much energy a surge protection device can handle. The grater the rating the longer it will last before it is “worn out”. More is better but at this time testing to determine joule ratings has not yet been standardized.
Some other considerations that can also be important:
A surge protector with USB charging ports can be a handy way to recharge your portable devices. These ports should supply at least two amps.
Always get more outlets that you need. It never fails to be true, you think you will only need four outlets but you end up needing six.
Get one with enough spacing for big plugs. Many devices use those “wall wart” power adapters that take up enough space for two outlets. Look for a surge protector with wider spacing between sockets, or sockets that can be rotated or moved, to accommodate chunky plugs.
If you are building a new home or remodeling your current domicile, properly organizing the electrical circuits can reduce exposure of power surges to sensitive equipment. Don't place wall outlets that are going to be used for computers, TVs, microwaves, and stereos on the same circuits that are powering large appliances with motors, such as refrigerators or freezers.
Never cover your surge protector with rug or other decorative items. This could cause overheating and a potential fire hazard
As with power strips you should never “daisy chain” surge protectors or plug one into an extension cord
How the magic works:
Most of the surge protectors in the $50.00 to $200.00 dollar range use the Metal Oxide Varistor, (MOV) technology. MOVs are a type of semi conductor that “clamps” the voltage by redirecting the electrical current to ground in the event of a surge.
Think of it as a water spigot. Under normal conditions the “valve” is closed and no current flows through the MOV. If a voltage surge occurs then the “valve” opens diverting the flow through the MOV and to ground, thus preventing the surge from reaching the protected devices.
When diverting the flow through the MOV it can get hot. Depending on the amount of surge and the duration the MOV can reach several hundred degrees F. That is why we need a thermal protection fuse to reduce the fire hazard.
The MOV can divert a finite number of power surges before they are destroyed. It may reach end-of-life after one big surge or many smaller surges over time.
Above and Beyond:
What if you need more protection?
In addition to surge protection these devices also remove stray frequencies and EMI interference often caused by other electrical components. In most cases these are not necessary. In fact most modern electronic devices already have their own internal power supplies that can accomplish the same task. So unless you have some very sensitive equipment or live in an area with a really poor quality utility service you probably don't need additional conditioning.
Series Mode Surge Protectors:
These are superior to MOV based surge protectors in just about every way.
- Clamping voltage is usually only two or three volts, a fraction of the 330 volts in a MOV under the same conditions.
- The Series Mode protectors do not rely on sacrificial components so they don't “wear out” after a few surges.
- Series Mode protectors do not just dump the unwanted current to ground. In environments where other devices use ground as a reference this can be critical.
The down side is that these devices can cost over ten times as much as the MOV based surge protectors. So unless what you are trying to protect cost more than a small car they probably aren't worth the money.
And just for the record, nothing is going to protect you from a lightning strike in your back yard.
Battery Backed Uninterruptable Power Supplies:
If you have a “Mission Critical” device that must keep operating even in a total blackout when the electrical supply drops to zero then you need a UPS. But that is the subject of a whole other newsletter.