Electrical Brownout problem

[WanderALot]

Hello,

Nords' home improvement thread got me thinking about a problem that I've been having. Every time our washer starts its agitation cycle the lights in the house dim. I know that this probably isn't a good thing for electronics so I'm wondering how I go about troubleshooting this. So it looks like the circuit that the washer is on is has too much of a load, but wouldn't the breaker just trip when this happens (or is it just that it's too quick for the breaker to trip?) Any good book on troubleshooting household electrical problems?

Thanks.

 

[JohnP]

WanderALot -

A washer is not typically a high current device so it is a little curious that it would cause incandescent lights to dim. Incandescent lights, though, can show quite a bit of dimming if you happen to have them on a lower setting of a dimmer circuit as in mood lighting or if you have lower wattage bulbs, say 40W or less, in the house. The higher wattage bulbs (75 W or greater) shouldn't exhibit much dimming from the washer agitator startup.

You may want to get yourself a cheap voltmeter - under $10 like at Radio Shack or Harbor Freight to plug into a wall socket to see if your voltage is especially low or subject to changes. A bunch of us here got Kill-A-Watt devices last year that measures wattage in various devices, it also can display voltage - I got mine on Ebay for about $30. Other things may cause dimming but probably should be left to a professional to track down and rectify.

Lets shed some light on this problem.

JohnP

 

[Nords]

A washer is not typically a high current device...

Except for the starting surge when it's spinning up. That's a high-torque draw on the electrical bus.

I spent years on submarines watching electricians shift the electric plant around among the various generators. What you're seeing is common for a large load coming onto a bus that can't maintain perfect voltage & frequency control.

It's also an indication that the house lights share the same bus with the washing machine. Voltage is probably getting hammered from 115-120 VAC down to 90 or even worse, and then it swings back up as the system adjusts and the washer gets up to speed. The transient's not low enough or long enough to trip the breaker. You might or might not see this spike on a Kill-A-Watt but it's impressive to watch.

Older houses have a single 100-amp feed coming in from one phase of a three-phase utility. Newer houses have two 100-amp feeds coming from two different phases of the utility. Modern houses may have 300-400 amps from not just two different phases but two different transformers.

If you're faced with just one 100-amp feed then there's not much to be done without an electrical contractor and an expensive upgrade. It might be worth it for a remodel or renovation but not a single load.

If you have two separate 100-amp feeds coming into both sides of your distribution panel then you could move the washer's breaker to the side that doesn't have all the lighting breakers on it. Separating the lighting breakers from other heavy loads is a sign of a professional & experienced electrical contractor.

If you can't do either of the preceeding then you could buy an UPS for your sensitive electronics (computers). TH can give you more performance details but I suspect that the quality of the voltage/frequency regulation will be directly proportional to the cost.

"Wiring A House" by Rex Cauldwell.

 

[cute fuzzy bunny]

Most home style UPS's are not "online", that meaning they pass current through and only switch to batteries when the voltage drops off to a point where its not usable any longer. That would help if it was a DEEP drop, but a little light dimming isnt good enough. Online UPS's are usually what you see in datacenters, and any portable versions are usually pricey. To be honest, havent priced one in a while.

Most electronics power supplies will take pretty big swings without too much of a problem. Its the long deep brownouts that can cause some damage to refrigerators/air conditioners and other such stuff that gets pissed when you slowly take its power away while its doing useful stuff like squeezing refrigerants and trying to blow off the heat. Oh yeah, and those 150,000 volt spikes dont make anything particularly happy either.

Unless the lights are REALLY dimming deeply and for several seconds...I probably wouldnt sweat it.

Everything Nords said is spot on. Many homes are hamstrung simply by the source of their power and the skill of the original electrician, minus almost anything that any hacker has done since the original panel was installed.

One thing you might try, although it isnt cheap, is one of those 'throttling' plugs aka "green" plugs that you plug a big appliance into and then into the wall. They usually take the hard peaks off of sudden draws. I have no idea if they're good for the appliance or not...supposedly they are. I've never used one.

Some stuff:
http://www.energyideas.org/formats/...itle&o=h,t,ts,ss,f,fs,ds&c=h,t,18,185,f,1,992

Seems like some people have good results and some dont, with different appliances.

Has it always done this? By asking, I'm wondering if the motor isnt getting a little long in the tooth and drawing too much power on startup.

 

[Gumby]

..

 

[Telly]

The lights that dim, are they on the same circuit as the washer?

When they dim, is it a momentary blip just when the washer starts its agitation cycle? Or do they stay dim during the whole cycle?

 

[WanderALot]

Thanks for all the replies guys. The lights dim for less than 1 second, so I'm not going to worry about it too much. I got Edison to come and take a look at their side of things and everything looked OK. I think the Edison tech who came out might have been Nords 'cause he said the exact same thing! Pretty impressed that the guy came out less than 4 hours after I called, that too for a non-emergency call on a Friday night!

It looks like my circa 1985 house has a 100 amp main breaker, although the guy said the main feed into the house can go up to 200 amps. I think the builder probably cut corners and didn't put the garage outlets (where the laundry is) on their own breakers.

 

[WanderALot]

The lights that dim, are they on the same circuit as the washer?

When they dim, is it a momentary blip just when the washer starts its agitation cycle? Or do they stay dim during the whole cycle?

The lights only dim momentarily for less than a second. I'm not sure if the lights are on the same circuit as the washer but I'm guessing it is. My outlet box isn't clearly marked and I've tried turned off breakers to see what's on what yet.

It is a smaller house (1300 ft) and the lights are in the kitchen close to the garage where the laundry is located.

 

[mathjak107]

your 100 amp service is probley too small and your getting a voltage drop when the washer starts...the other thing id check is incoming voltage maybe its on the low side to start with ,thats a utility problem....its really not a problem as long as everything is coming up to speed in a normal amount of time

 

[BigMoneyJim]

I hadn't heard of a green plug before. In my search this was an early result:

http://yarchive.net/electr/green_plug.html

It claims the green plug kills refrigerators by underloading and therefore overheating the compressor coils. I can't speak for the authority or authenticity of the source.

_________________________________________________
BTW, on the two 100-amp feeds for breaker panels, my understanding is that each column of breaker slots alternates which feed it uses as it goes down, so the top left breaker may be on the left feed, and the 2nd down from top left is on the right feed. This allows side-by-side ganging of opposite-phase 120v breakers for a 240v circuit. In other words you couldn't put, for example, all the lights on the left side of the panel and all the appliances on the right and assume the lights are on separate feeds from the appliances. But with a little work you can indeed separate the feeds.

 

[Nords]

BTW, on the two 100-amp feeds for breaker panels, my understanding is that each column of breaker slots alternates which feed it uses as it goes down, so the top left breaker may be on the left feed, and the 2nd down from top left is on the right feed. This allows side-by-side ganging of opposite-phase 120v breakers for a 240v circuit. In other words you couldn't put, for example, all the lights on the left side of the panel and all the appliances on the right and assume the lights are on separate feeds from the appliances. But with a little work you can indeed separate the feeds.

In our panel the top two left-handed breakers are both full-size breakers ganged together to make a single 240V breaker. So the dryer heaters (or the oven coil) need a leg from each phase.

But I sure hope the washing machine discussed here is a 120V motor. (A 240V motor making that kind of a spike on a circuit would have some serious issues.) A 120V motor gives the electrician some flexibility in making sure that the washer motor, the fridge, and the dryer motor are at least on a separate bus from the lights.

"Wiring A House" talks about grouping certain loads (like the dryer and the stove) on the left and others (lighting circuits) on the right, so manufacturers probably make different types of panels that allow contractors to do it whatever way they prefer.

 

[mathjak107]

its called load balancing..the panel has 2 copper or aluminum bus rated at say 125 amp each....the idea is to make sure you dont exceed the rating on anyone bus so you stagger the heavy 115 loads....in a 3 phase panel its the center buss you worry about overloading with 240v loads....

 

[mathjak107]

another comment about ups systems...its thought an off line ups runs off ac and switches to the batteries when power fails while a line interactive one runs off the batteries all the time and the ac only serves to charge the batteries...not true....while maybe early systems tried to work like that that idea was quickly done away with...over heating batteries and short battary life plagued early units....both types pass ac power but the line interactive offers voltage regulation and stabilization as well as almost instant switch to battary power with no delay when power fails..cheaper off line units dont perform as well

 

[AltaRed]

My APC UPS on my home computer system works flawlessly. Was very common north of Houston to lose AC power for short periods (that dang Entergy outfit from Louisiana). The UPS would run the computer system nicely for 10 minutes or so (depending on how much load I had on it) and then commence/complete a PC shutdown before the batteries drained.

 

[mathjak107]

for home use even the cheapie units are fine......the main problem the on-line active units deal with is stabelizing in-consistant voltages or in syncronizing equipment with motors...just dealing with power failure an off-line does the trick.......

 

[cute fuzzy bunny]

Just to clarify the difference...the on-line units provide a clean smooth power output from the batteries, while the batteries are constantly charged from a separate circuit. Loss of power means nothing to the output, until the batteries run out. Offline units, as are most common when paying under a thousand bucks for the UPS, run directly from the AC output, detect a low voltage situation and switch to the batteries, then switch back when the power comes back. You CAN get a little voltage drop in the unit before the batteries kick in, and you CAN get a little surge when the batteries kick back out.

WAY better than nothing and a modest size unit that I frequently get for $10-20 after coupons and rebates will run a tivo/cable modem/VOIP box/phone for 10-15 minutes, or a well equipped computer for the same time period.

 

[mathjak107]

Just to clarify the difference...the on-line units provide a clean smooth power output from the batteries, while the batteries are constantly charged from a separate circuit.  Loss of power means nothing to the output, until the batteries run out.  Offline units, as are most common when paying under a thousand bucks for the UPS, run directly from the AC output, detect a low voltage situation and switch to the batteries, then switch back when the power comes back.  You CAN get a little voltage drop in the unit before the batteries kick in, and you CAN get a little surge when the batteries kick back out.

WAY better than nothing and a modest size unit that I frequently get for $10-20 after coupons and rebates will run a tivo/cable modem/VOIP box/phone for 10-15 minutes, or a well equipped computer for the same time period.

not exactley...on line no longer run off battary power when there is ac power available.....they actually provide a pulsed output created by quick switching scr's called pwm (pulse width modulated)...its really not smooth at all,,its a processed regulated output that holds voltage regulation in a very tight range even if voltage drops on the input...its kept at a constant voltage output but the waveform acutally looks like a sawblade..the equipment you power couldnt care less

on the other hand the cheaper off line system uses straight ac power,,,probley the smoothest waveform but very little regulation if you get over or under voltage...if your interested in learning more about ups systems i can send you to a few websites chock full of info....

 

[cute fuzzy bunny]

Hmmm...:

"Under normal operation the online UPS is always running off the battery, using its inverter, while the line power runs the battery charger. "

"The online UPS is the most advanced and most costly UPS. The inverter is continuously proiding clean power from the battery, and the computer equipment is never receiving power directly from the AC outlet."

Can you point to some online product that works as you suggest, because it sounds like what you're talking about is a regulated offline system.

 

[mathjak107]

oops yes fuzzy you are correct..origionally i was refering to line inter-active and confused you when i refered to it later on as on line.....actually there are 3 types of systems
the standby as we mentioned,,,the line interactive which is the better grade we normally see for home use and the type i described and the type you you are refering to which is a "true ups" or on-line ....the on line does work off batteries to power the inverter section primarily...these are very expensive and arent very common for home use but they are the best.......there are are a few line interactive units that try to run off battary power primarly too but they are plagued by over heating batteries and short life

 

[mathjak107]

found this explanation:


There are two types of on-line UPS: parallel on-line and series on-line.

In the parallel UPS their batteries and the mains voltage are connected simultaneously to the equipment outlet. As the battery is always connected to the UPS outlet, there will be no voltage interruption. However, as mains power is always connected to the UPS outlet, any fluctuation in the mains voltage will be present in the UPS output, and consequently in the computer. Therefore we say that in this type of equipment the output is not insulated from the input.

This insulation is attained in the series UPS, which is the best type of available UPS - it is what we call the true UPS. In this equipment the computer is fed only by the battery and only by the battery. When mains fails, there is no type of interruption. It is as if the electrical voltage present at the UPS input is used only to load the battery when it goes low. The UPS output is completely insulated from the input. With that, any problem in the mains power network (fluctuations, noise, etc) will never affect the computer connected to the output of this type of UPS

 

[perinova]

The breaker not tripping shows that your equipment is all right.
However the lights are dimming so you have a line that cannot handle the load. Which could be a major hazard if it is inside your home (could overheat and cause fire).
I would check the voltage close to the light, also close to the breaker etc to pinpoint where it is coming from. And I would replace the line. Make sure you are using the proper gage wire. Usually the standard is 15A in this case you may need more than that
It could also be the whole supply to your house (if you are connected to the main you may be at the end of the line). In this case you can't do anything about it . Just complain and ask them to fix it.