Surge protectors and CPAP machines

westom wrote:

JeffL wrote: I'm not buying it. If you daisy chain 10 power strips together, it's the same as an extension chord, only with 10 sets of outlets along it's length.

Well, then I guess those dogs did not die in a fire - that the report said was created by daisy chained power strips. I guess OSHA really did not create those safety rules.

The dogs probably died because there was too much load on one circuit, or a frayed cord somewhere. One way to do that is to plug in a whole bunch of small devices into one circuit. Daisy chaining power strips is one way to put too much load on one circuit. Having a bunch of cords and power strips gives you more places to have a frayed cord or bad connection.

You can start a fire with one device plugged into one power strip or extension cord if the device draws enough power.

Circuit breakers help reduce the risk of fire, but don't always eliminate it. In particular, a circuit breaker is good for a "dead short, quick fire" situation. They're less effective against slow heating that can cause a fire.

Yes, it's better to not daisy chain power strips, especially if you do a lot of them. However, just plugging one into another doesn't cause a quantum leap in risk vs. just having one strip.

OK, I've given this some thought, and I I'm going to back down (a little ).
Here is situation in which the circuit breaker will work, but you'll burn the place down -
You daisy chain two or more power strips, or even just use one, and load it (or them) with high wattage devices, such as two or more electric heaters. The first power strip, which is probably rated at 15 amps (1800 watts) is going to be carrying the current of everything plugged into it. So if you have 2 1,000 watt heaters plugged in, the first power strip is going to be overloaded, and something is going to get hot. It's carrying about 17 amps, so a 20 or 30 amp circuit breaker isn't going to care. The situation gets much worse with more heaters are added. There would also be a problem using a light gauge extension cord.
That's probably the reason for the OSHA rules.
I made the mistake of assuming that people have a little knowledge and common sense.
If you are powering a couple of lamps, and a few low power devices (like a clock radio), there shouldn't be a problem.

I have my cpap plugged into a battery backup device for computers. This device will also catch power surges and dips. When the power goes out, I have about 30 minutes of backup power before the cpap goes out, which is nice, but the thing still beeps to warn me the power is out, so sleeping through it is out of the question. If you have any of the power supplys for your computer system sitting around, put them back to work!

Bobshouse wrote:I have my cpap plugged into a battery backup device for computers. This device will also catch power surges and dips. When the power goes out, I have about 30 minutes of backup power before the cpap goes out, which is nice, but the thing still beeps to warn me the power is out, so sleeping through it is out of the question. If you have any of the power supplys for your computer system sitting around, put them back to work!

Can't the beeping be disabled or at least the connecting wire cut to disable it.

I am planning on putting an unused UPS on my APAP & had thought about the beeping. Sure hope I can easily disable the beeping.

westom wrote:

JeffL wrote: I'm not buying it. If you daisy chain 10 power strips together, it's the same as an extension chord, only with 10 sets of outlets along it's length.

Well, then I guess those dogs did not die in a fire - that the report said was created by daisy chained power strips. I guess OSHA really did not create those safety rules.

Some safety standards limit a numbers of receptacles to six. An extension cord with 10 outlets along its length typically would sell without safety listings.

Standards also define an extension cord as temporary when used for less than 90 days. Obviously that cord should not be under a rug or located where tripping might occur. Many obscure safety rules apply.

Westom, would you recommend this surge protector from Trip Lite? It seemed like it had several outlets for hair dryers and space heaters in addition to my machine. (Agency approvals: UL1363; cUL; UL1449 3rd Edition)

STL Mark wrote:

westom wrote:

JeffL wrote: I'm not buying it. If you daisy chain 10 power strips together, it's the same as an extension chord, only with 10 sets of outlets along it's length.

Well, then I guess those dogs did not die in a fire - that the report said was created by daisy chained power strips. I guess OSHA really did not create those safety rules.

Some safety standards limit a numbers of receptacles to six. An extension cord with 10 outlets along its length typically would sell without safety listings.

Standards also define an extension cord as temporary when used for less than 90 days. Obviously that cord should not be under a rug or located where tripping might occur. Many obscure safety rules apply.

Westom, would you recommend this surge protector from Trip Lite? It seemed like it had several outlets for hair dryers and space heaters in addition to my machine. (Agency approvals: UL1363; cUL; UL1449 3rd Edition)

that strip would work because it only has one MOV, thus bypassing the problem (power feedback) of having MOVs in serial with multiple power strips.

STL Mark wrote:Westom, would you recommend.....

Westom is a troll - please dont feed it

When buying things, by quality, only buy UL compliant devices. Surge devices nee to have MOV to short out (kill) the overvoltage and a Circuit Breaker to turn off overloads. It's also good to have a inductive element to smooth current spikes. Also to work correctly the strip needs to be plugged into a correctly wired power outlet.

By using quality surge suppressor, it doesn't matter how may you hook together, overloads should pop the overloaded suppressor.

Unlike what was posted in a prior post, MOV's aren't hooked in series, they are hooked accross the power lines, when the voltage get too high they short and pop the circuit Breaker. Jim

Yea, what would a EE possibly know about it...

Goofproof wrote: Unlike what was posted in a prior post, MOV's aren't hooked in series, they are hooked accross the power lines, when the voltage get too high they short and pop the circuit Breaker. Jim

They do go across the power line, but more than one can be connected in series to increase their voltage rating.
I wouldn't call popping the breaker proper operation.

http://www.circuitstoday.com/metal-oxide-varistor-mov

JeffL wrote:

Goofproof wrote: Unlike what was posted in a prior post, MOV's aren't hooked in series, they are hooked accross the power lines, when the voltage get too high they short and pop the circuit Breaker. Jim

They do go across the power line, but more than one can be connected in series to increase their voltage rating.
I wouldn't call popping the breaker proper operation.

http://www.circuitstoday.com/metal-oxide-varistor-mov

My reference to POPing the circuit, refers to the action of forcing the circuit to blow open.

The type of circuit is called a Crowbar circuit. By putting multiple MOV's across the line, allows the weakest one to blow first followed by the next weakest, another chance to control the spike, until they all burn out. Most manufactures only use one to save costs. Jim

JeffL wrote: If you are powering a couple of lamps, and a few low power devices (like a clock radio), there shouldn't be a problem.

Some facts are too complex for this discussion.

An example. How many amps does a 100 watt 120 volt light bulb first demand? Most would assume 0.8 amps (100 watts divided by 120 volts). However an incandescent bulb consumes maybe 7 amps on startup. Industry standards recommend not daisy chaining power strips (protector or non-protector types) for this and other reasons.

westom wrote:

JeffL wrote: If you are powering a couple of lamps, and a few low power devices (like a clock radio), there shouldn't be a problem.

Some facts are too complex for this discussion.

An example. How many amps does a 100 watt 120 volt light bulb first demand? Most would assume 0.8 amps (100 watts divided by 120 volts). However an incandescent bulb consumes maybe 7 amps on startup. Industry standards recommend not daisy chaining power strips (protector or non-protector types) for this and other reasons.

That's why the Circuit Breaker, it should blow before the wiring or device heats up to a dangerious level, Power Strips without Circuit Breakers should be destroyed, as theyare unsafe. A lamp load does as you suggest, but the overload is very short timed, motors however draw heavy on start up and take longer to get to there normal level draw. (Starting Amps). Jim

XPAP's don't draw much power.

Goofproof wrote: By putting multiple MOV's across the line, allows the weakest one to blow first followed by the next weakest, another chance to control the spike, until they all burn out. Most manufactures only use one to save costs.

If any MOV blows, then MOV manufacturer specifications are violated. MOVs must never "blow". That failure is why MOVs have caused house fires.

Protectors include a thermal fuse so that potentially destructive surges do not cause MOV failure - cause a fire. Sometimes that fuse does not open fast enough. Then a power strip protector fire may occur.

That fuse is completely different from a power strip's circuit breaker. The thermal fuse only disconnects MOVs from the surge. And leaves the surge connected to all appliances.

Catastrophic MOV failure is one of many reasons why power strip protectors should be used only in conjunction with a 'whole house' protector.

A protector's light reports only one type of protector failure - catastrophic MOV failure. Catastrophic failure violates MOV manufacturer requirements. IOW a protector's indicator light reports when a protector was grossly undersized. Unfortunately, that failure foolishly gets consumers (who don't learn basics) to recommend and buy more grossly undersized protectors.

Protectors that fail or burn out provide virtually no effective protection. Are a threat to human life. Effective protectors perform without such failures. And another reason why informed consumers also earth a 'whole house' protector.

Goofproof wrote: That's why the Circuit Breaker, it should blow before the wiring or device heats up to a dangerious level, .

Should. All those numbers are correct. The risk is low.

However, a 15 amp circuit breaker does not trip on 16 amps. Circuit breakers are safety devices that work "most" but not 'all' the time. Explains why daisy chained power strips caused a fire that killed some 20 dogs.

A room should be wired so that a wall receptacle is about 6 feet or less from a CPAP. No reason should exist to daisy chain power strips since the CPAP and one power strip should be well more than 6 feet. Long enough to connect to a wall receptacle. If not, then a new wall receptacle is required.