Is there a difference between a surge protector and a circuit breaker?

[Eeezee]

I'm no EE. I bought some power squids on woot.com recently that have circuit breakers on them. Some of the posters in the forums were suggesting that you need to buy a surge protector for each power squid.

What's the difference between a surge protector and a circuit breaker? I am confused!

 

[TastesLikeChicken]

A breaker will interrupt current flow under a fault condition. A surge protector will not.

 

[KLin]

circuit breakers prevent too much current from flowing through electrical wiring.

surge protectors prevent electronic equipment from getting a possible damaging power surge.

 

[Leros]

Circuit breaker - protects against overdraw (too much current)
Surge protector - protects against voltage spikes


Circuit breakers protect your wiring from burning up. If you plug in too much stuff, you can draw too much current and bad stuff happens.

A surge protector protects against voltage surges, meaning the voltage goes too high (above the normal 110-120). This can damage some electronics.

Neither of them protect you from low voltage (voltage going under 110-120), which can damage electronics too. Ever have a power outage and notice the light bulbs glowed a tiny little bit? That because the power isn't out, but the voltage dropped too low. I lost the electronics in a stove due to this.

 

[JohnCU]

to add a bit to the thread even though it's already been answered, a circuit breaker in the home or fuse is used to prevent damage from the electrical wiring, not the actual piece of equipment.

 

[Mark R]

A circuit breaker detects potentially dangerous faults in the appliance and will disconnect the power in the event of a fault. There are a variety of different types of circuit breaker which serve different purposes:
- Overcurrent circuit breaker - detects overloads and short circuits (most common type, virtually all circuit breakers have this type of function). This is to prevent overheating wiring or plugs/receptacles.
- Earth leakage circuit breaker (also called ground fault or residual current circuit breakers) - detects electricity that 'leaks' from an appliance to ground, but not via the power cord. E.g. a loose wire inside the appliance touches the metal case, and a person touches the metal case completing the circuit to ground. This type of circuit breaker will disconnect the power before there is enough time to deliver a fatal shock.
- Arc fault circuit breaker - detects arcing/sparking which may pose a fire risk.

The latter 2 types are specialised, and expensive - but are used where required for safety, and in certain circumstances their use is required by electrical codes. E.g. it's good practice for any portable power tool or any receptacle which could be used to power an outside applicance shoudl be fitted with an earth leakage breaker.

A surge protector diverts surges of energy that occasionally flow in power grids. There are many causes of pwer surges - e.g. lightning strikes, large motors (e.g. AC units), nearby industrial equipment. These can cause damage to sensitive electronic equipment. The protector will divert some of the energy away from the equipment in an attempt to prevent damage.

Electrical surges vary in frequency and severity. If you live in an area with frequent storms, you are more at risk than a more temperate area. If your power comes via long overhead lines, you are more at risk, than if you live in a city center where lines are short and buried underground. If you have heavy industrial equipment nearby (e.g. the farmhouse with large grain dryers nearby) you are at higher risk.

All sensitive electronic equipment contains basic level surge protection, sufficient for the minor surges from AC units, refrigerators, etc. However, it won't be sufficient for larger surges. That said, no surge protector for home type use will protect from a major surge (e.g. due to a lightning strike in the neighborhood).

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The squid should have a circuit breaker on, so that you avoid overloading the receptacle you are plugging the squid into. A surge protector may be useful if you have substantial expensive equipment, but is not essential - if you've got $10ks worth of plasma TV, HTPC, and other stuff, then you may consider the surge protector as a form of 'insurance'. If you do decide you want a surge protector, it will only really offer useful protection for equipment plugged directly into it.

 

[Eeezee]

Okay, so I should buy surge protectors for my power squids then, if I want to protect my equipment from voltage spikes. I'm not really a risk, but the most of my stuff is surge protected anyway (with the exception of a few lamps). I don't have a lot of expensive stuff because I'm a poor college student, but investing in some surge protectors as I need them seems like a sound idea.

Here's another question, what if I were to plug a power squid into a power strip that is surge protected? Is this advisable if I'm mostly using low wattage appliances?

 

[TastesLikeChicken]

Eh. Others may disagree but, honestly, I think it'd be a waste. Most electronics have their own form of voltage regulation (many are using inverters to convert to DC voltage) so you don't really need to worry unless you get a major surge. In that case the breakers on your squid would probably blow first.

 

[Paperdoc]

Originally posted by: Eeezee
Okay, so I should buy surge protectors for my power squids then, if I want to protect my equipment from voltage spikes. I'm not really a risk, but the most of my stuff is surge protected anyway (with the exception of a few lamps). I don't have a lot of expensive stuff because I'm a poor college student, but investing in some surge protectors as I need them seems like a sound idea.

Here's another question, what if I were to plug a power squid into a power strip that is surge protected? Is this advisable if I'm mostly using low wattage appliances?

Re your "another question": no problem. You will see frequently warnings about not plugging too many items into a circuit, or making a nest of extensions, etc. They always say you'll overload the circtuit, but that will not happen. The circuit in the walls was installed with cables for the proper current capacity and a fuse or circuit breaker at the panel limits it to that current. If you plug in enough devices to exceed the capacity of the in-wall cabling, its breaker will trip out to protect that.

The real source of trouble is someone who uses a light-weight extension cord somewhere and then connects a heavy device (or several smaller ones). Here it's possible to overload the light extension cord without overloading the main circuit, so the breaker does not trip. The extension cord can overheat and cause real problems in this situation. The root of this trouble is too many things plugged into a LOW CAPACITY EXTENSION, and not the circuit load.

The less common type of trouble is using cords or plugs in poor condition. That includes cords that have (often hidden) frayed wires inside that reduce capacity, thereby increasing the danger of overheating, and these can result from cords that are exposed to mechanical abuse (like runing them under rugs where they get walked on). It also includes cords, sockets or multi-outlet taps with corroded contacts. Poor contact points produce high resistance at that spot, creating significant heat generation at one concentrated location under heavier loads.

So most of these problems are not in circuit loading, but in misuse of equipment added by the consumer.

By the way, just a small warming on surge protectors. The good ones can be quite sophisticated systems (and expensive). But the cheap ones may only work once. Many of these are based on simple MOV units connected between hot and neutral lines. They conduct virtually no current under normal curcumstances, but when voltage rises beyond a certain threshold they suddenly become great conductors and short out the high voltage for a brief time. This prevents the surge from going on down the line to your TV or whatever. However, during the brief time the MOV is doing its job it may well destroy itself with all of the enrgy being diverted through it. So when it's done, it is no longer there to repeat the process for the next spike. Your surge-protected power bar still appears to work just fine, but in fact there is no more surge protecting function. It is very difficult for the average homeowner to know this has happened.