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A New Shade of Green

By Sherry Listgarten

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Fun and games with your electric meter

Uploaded: Oct 11, 2020
I remembered the other day that I made a New Year's resolution to decrease our electricity use by 10%. I pretty much forgot all my resolutions in the spring (!), so now it’s cram time. Here’s what I learned this past week as I tried to figure out the easiest way to shave 10% off of our electric use.

The bills show we’ve been using around 800 kWh for each of the last few months. That seemed high to me, since we have a modest house, small family, and few big electric appliances. I figured 10% should be very doable. I’d start by finding out how much we’re using at different times to see if that pointed to some low-hanging fruit.

We don’t have a digital meter, so I had to go out to the meter and measure how fast the little wheel is spinning. Do you know what I’m talking about? Our meter looks like this.


The five dials on top show how much power has been used over time, while the spinning wheel shows how much power is being used right now.

The meter reader reads the five dials on top each month to figure out how much was used in the past month. You can also check it each day to see how much you use each day. In my case, it goes up between 20 and 30 kWh each day. But that doesn’t really help figure out where the electricity is going. The spinning wheel is more helpful for that.

The “7.2 Kh” in the corner means that the wheel does a full rotation for every 7.2 watt-hours used. If you time the rotations you can figure out how much power is being used. For example, if it takes ten seconds for one rotation, then you are getting 7.2 watt-hours in 10 seconds, or 7.2 * 6 * 60 watt-hours in one hour, which means 2592 watts is being used. (1) That could mean you have some lights on and someone is running a hair dryer, for example.

Take a look at this set of short videos I made of our meter to give you an idea of what this looks like.

How fast does our bill say our wheel is spinning? 800,000 watt-hours per month is around 1111 watt-hours per hour. (2) In other words, on average, every hour of every day, the house is using 1111 watts. That means the wheel is spinning 1111/7.2 times per hour, or 154 times per hour, which is once every 23 seconds. So, I went out to check.

I was doing this in the middle of the day, so there wasn’t much on except the dining room light, where my daughter was “in school”. One rotation took about 45 seconds, so about 576 watts. That seems like a lot of electricity for doing nothing. So I turned off circuit breakers one by one to see where the power use was happening. It wasn’t until I got to circuit breaker #12 that I saw the wheel really slow down, to 62 seconds per rotation or about 418 watts. What are the 160 watts behind circuit breaker #12?


Turning off circuit breaker #12 led to a big drop in power use.

“FAMILY RM OUTLETS. UTILITY RM. HEAT”. Hmm. There’s nothing much plugged in in the family room, we don’t have a utility room, and the heat is off. Moving on, I continued turning off the circuit breakers, leaving the dining room light to last. There were only small changes, so when just the dining room light breaker was left, the rotation speed was still about 73 seconds, or 355 watts. Yikes, that is one power-hungry light fixture. Once that was turned off the wheel stopped spinning.

The dining room light, shown below, has fourteen little halogen bulbs, each drawing up to 40 watts. I had replaced a few with LEDs when they burned out, but we rarely used this light until recently. Now with “distance learning” it’s used for much of the day. Time to replace the rest of the bulbs!


This flying-saucer-like light fixture has 14 small G9 halogen bulbs, each 40 watts. Fortunately they now make LED equivalents that are only 4 watts.

Now I just had to figure out the mystery with circuit breaker #12. I unplugged everything in the family room, but it made no difference. What was the “utility room”? The water heater closet in the garage? I turned off that switch, but it again no difference. Could it be the hall closet with the ethernet panel and radiant heat manifold? The only thing plugged in there are the modem and router, so I unplugged those but it only saved about 20 watts. I opted to just leave that circuit breaker off and if we didn’t notice, so much the better.

So I got the daytime use down a bit, but it wasn’t that high to start with. How could our bill be so high? The house supposedly sees an average of 1111 watts, and given that night use is probably more like 300 watts (3), that meant the daytime average was around 1500 watts. But I was barely scratching 600. We do have an electric car, and the charger’s dashboard shows it’s been using about 130 kWh per month. Subtracting that leaves a daily average of 931 watts, or 1246 daytime watts. Where is that coming from? We don’t run the dryer or use the oven that much.

Just for fun, I turned on every light in the house -- indoor lights, outdoor lights, closet lights. That got the wheel spinning like crazy, just 4.3 seconds per rotation for a total of over 6000 watts. So at least it was possible to get a high number. But in reality we don’t use that many lights and the normal-shaped bulbs we’d replaced long ago with LEDs.

It made me realize that evenings are probably going to use a lot more power than midday. Would they make up for the difference? I measured during dinner, with kitchen lights and the range hood on, and saw the wheel spinning once every 20 seconds, or about 1300 watts. That was getting there. Later, with a few more lights and the TV on, the wheel was rotating every 14 seconds, or about 1850 watts. Dishwasher on? 2250 watts were being used.

I estimated our usage over different periods of the day:
- Night: 8 hours at 300 watts
- Morning: 3 hours at 1000 watts
- Midday: 8 hours at 600 watts
- Evening: 5 hours at 2000 watts

That adds up to about 20kWh for the day. Our bill says we are using about 800/30 = 27 kWh each day. If I add on the EV, which is using about 130/30 = 4-5 kWh per day, the bill starts to make sense, and I have a better idea of our electricity usage.

With that in mind, how can I drop our use by 10%? I changed the bulbs in the dining room light fixture to LEDs. It went from using about 350 watts to using only about 20. That was an easy win. I also changed the dishwasher to do the “Energy Saver Dry”, which is just a drip dry. The manual says to be sure there is rinse-aid. I tried it once and it worked fine. What about circuit breaker #12? I realized a few hours later, when I opened the refrigerator, that in fact it controls power to the refrigerator! I can’t exactly turn that off.

Could I replace the refrigerator with a newer one? I have two refrigerators. The small one in the garage is just a few years old and uses an average 40 watts based on its Energy Star label. The bigger kitchen one is from 2004 and seems to use 2-3 times that much. If I were to replace a refrigerator, it would be that one. But it works really well and would cost a lot to replace. I’m going to wait. (4)

The only other thing that we use a lot that draws a lot of energy are the kitchen lights. It’s a set of three weird fixtures with several kinds of bulbs.


Three light fixtures in the kitchen have around 20 halogen bulbs, only a few of which are LED.

I’ve started replacing them with LEDs as they burn out, but there are many halogens left. How much power does it use? I measured the wheel rotation with and without the lights on and saw one fixture using around 200 watts and all three using over 600 watts (!!). We very often have at least one of the light fixtures on, so I bit the bullet and bought LED replacements for all the bulbs. It cost around $80 to buy the replacement bulbs (5). If I save 1 kWh each day, then at $0.19/kWh it will take about 1.5 years to pay that off. I’m okay with that.

We also have some lights in the family room that are pretty bright, though I’m not sure there is a bulb that will fit. I’ll take a look. Besides that, savings would likely come from the dryer, the oven, or the EV. Drying less and driving less don’t seem likely. (We already bike a lot.) I can probably preheat the oven closer to when I’m going to use it. Mainly, I’ll see how far the bulb replacements and dishwasher setting get me.

So, after all that, what is my advice for you?

1. Look at your meter. It’s kind of fun. All you need to do is time one rotation in seconds, then divide 25920 by it to find out how much power is being used. (This assumes you have a 7.2 Kh meter, which most of us do.)

2. Look in the early morning before anyone is up. This is your baseline load. Is it what you’d expect?

3. Look during a “normal” time of the day. Working from home means you are using electricity differently than last year. Are there changes you can make?

4. Nights are getting longer. Test the lights you use most often. Do they move the wheel a lot? LEDs are available now for many kinds of bulbs. Be careful of the size, though, since some LEDs are a little bigger.

5. Pay attention to the few big-time energy hogs. In our house it’s the EV charger, the electric dryer, and the oven. Can you use them less?

6. Don’t trust the labels on your electric panel!

This might be a fun project to involve kids in, too. Can they guess which are the energy hogs?

Notes and References
1. The easy way to do this is to take the rotation time in seconds (10 seconds in this case) and divide it into the number of seconds in an hour (3600) multiplied by the number of rotations per hour (7.2). In other words, the wattage being used is 3600 * 7.2 = 25920 / (rotation time in seconds).

2. Just divide 800,000 by the number of hours in a month, or about 30 * 24 = 720.

3. I confirmed early one morning that nights seemed to use about 300 watts.

4. This is a case where I think it’s fair to fall back on using carbon offsets.

5. The kitchen lights use GY 6.35 and MR 16. The oven hood uses a different kind of MR 16. The dining room light has G9 bulbs. The wall lights have R7S’s. It’s nuts. But at least the bulbs are available now.

6. Silicon Valley Power has a good reference for electricity use for typical appliances.

Current Climate Data (September 2020)
Global impacts (July), US impacts, CO2 metric, Climate dashboard (updated annually)

I included this graphic last time, but I want to include it again because I think it’s important. Sometimes readers ask how much of a difference the pandemic has made in our emissions. You can see the projected pre-covid emissions and the projections now, which are somewhat better. You can also see where we are relative to the Paris targets, and where we need to be to stay below 1.5C or 2.0C.


Our emissions reductions lag far, far behind where we need to be. (Source: CNN, 2020)

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Comments

 +   7 people like this
Posted by Jennifer, a resident of another community,
on Oct 11, 2020 at 7:08 am

Jennifer is a registered user.

A few years ago, my husband and I decided to reduce our PG&E bill. Our kids are grown, our house is large -- but we can do it! We gave it no extra effort, and cut our bill in half for over two years. It's a little higher with me working at home now. We raised our temp on our AC (not 78), turned out lights we weren't using, I used the oven a little less and did larger loads of laundry. I also stopped having the tv and computer on at the same time. Unless you've been very conservative all along, reducing your energy use is easy.


 +   5 people like this
Posted by nancygrove, a resident of Atherton: West Atherton,
on Oct 11, 2020 at 8:49 am

nancygrove is a registered user.

Sherry, thanks for the delightful and informative "mystery story"! Kudos for having learned how to read the revolutions on an analog electricity meter. This is a more practical way (certainly more complete way) of evaluating one's energy use than doing what we did, which was going around plugging appliances in to a Watt's Up meter (which only works for electrical devices that use a plug and an outlet.)
I guess I'm curious, though--you live in Palo Alto, so your default electricity product is 100% renewable. Is this a good use of your time and energy? I acknowledge that it's a great exercise for folks in cities that are not in that position. I also acknowledge that "100% renewable" still involves (I believe) annual vs. hourly accounting and frequently use of offsets, so using less is still less carbon-intensive than using more.
Are you still burning natural gas in your water heater? Have you done a blog on heat pump technology? apologies if I've missed it!


 +   5 people like this
Posted by Tom, a resident of Menlo Park,
on Oct 11, 2020 at 9:10 am

Tom is a registered user.

Thanks for sharing the adventure with us. I see the cognitive dilemma for us as "resource conservers". We are the descendants of folks who pulled the arrowhead out of the mammoth and re-used it. We think our best resource conserving move is to use old tech to the end of its life. You found fantastic financial rewards in upgrading $80 of lightbulbs that return $80 of savings twice every three years. I wish my IRA did that! Lots of people make the mistake of playing 'water heater roulette' where they have a 10 year old (2010) Obama-era gas water heater and they want to "use it up" before replacing it with a new efficient heat pump water heater. Waiting is not a good plan unless you like being at the plumber's mercy for whatever he wants to charge for whatever he has left-over on the truck that day. While it makes sense to wear socks until they give out, it doesn't make senses to hang onto environmentally obsolete things like halogen (or regular incandescent) light bulbs and gas water heaters. Replace energy dogs early, keep socks and t-shirts to the bitter end.


 +   5 people like this
Posted by Deny, a resident of Barron Park,
on Oct 11, 2020 at 9:25 am

Deny is a registered user.

"We are the descendants of folks who pulled the arrowhead out of the mammoth and re-used it."

Wish it was still in the family, along with a couple of tusks!

...

Another great read - thanks, Sherry


 +   5 people like this
Posted by KOhlson, a resident of Old Palo Alto,
on Oct 11, 2020 at 10:36 am

KOhlson is a registered user.

Enjoyed reading the walk-through, but this really seems to net out with: double-check that you're using LED bulbs, especially in fixtures that are heavily used. You rationalized your way out of "spending big," and I agree with that. As mentioned above, I would be interested in an analysis of switching to heat pumps. And if solar panels in Palo Alto can assist in the economics.


 +   4 people like this
Posted by Neal, a resident of Community Center,
on Oct 12, 2020 at 6:52 am

Neal is a registered user.

Thanks for a very interesting and informative article. I reviewed my utility bill and I averaged 755 kWh per month for the year. If my math is correct my electric bill averages $123/month. If I reduced my consumption 10% I would save only $12.30/month. That's not much of an incentive to conserve. On the other hand, I recently replaced my dish washer, clothes washer and will probably be getting a new and more efficient refrigerator soon. I'm replacing appliances because they are simply wearing out, not because I'm trying to conserve energy or save money.. So I'm making progress with out even trying.


 +   4 people like this
Posted by Sherry Listgarten, a Almanac Online blogger,
on Oct 12, 2020 at 10:24 am

Sherry Listgarten is a registered user.

Wow, I love these comments.

@Jennifer: That is really impressive. I agree that AC is a great thing to adjust if you have it. Still, 50%! I'm impressed.

@Nancy, great question. I would definitely say that reducing gas use is more important than reducing electricity use. I did a post on the emissions effect of using heat pumps but I haven't done one on the technology or one on the cost. I should do one, I agree. Thanks for the suggestion!

@Tom, I wish plumbers had a lot more heat pump water heaters on their trucks...

@KOhlson, I agree, in a way it's a really stupid post. "LEDs help". Don't we know that? But there's a difference between knowing something and doing something. So my emphasis here is more about "Look at your meter" or "Ask your kids to look at your meter." Because I think, when you do that and you see the difference it makes, you may be more inspired to make the change. I definitely agree it would be nice to have a cost analysis of heat pumps, and I will put it on my list! The city already has a really nice, detailed tool for evaluating solar here.

FWIW, I was a little surprised that lighting is such a big part of my bill. I had read it's normally 15% or so. In my case I think it's more like 50%.

@Neal, absolutely, efficiency standards have made an enormous difference for us, and are one of the most effective levers we have for addressing climate change. That is why it is so dismaying that the current administration is fighting so hard against vehicle fuel efficiency standards, against even something simple like LEDs. It is just a travesty, for exactly the reason you allude to.

Anyway, thanks for the really terrific comments.


 +   3 people like this
Posted by MM, a resident of Menlo Park: Fair Oaks,
on Oct 12, 2020 at 12:50 pm

MM is a registered user.

Look into joining OHM Connect. They help you to be more aware of your usage of electricity by having challenge hours to see if you can use less.

Other ideas:
-dry your clothes on the line. Easy, saves elastic, good for the earth and we have been doing it for generations.
-why do you need to use a dishwasher? If you have a big family?
-Airconditioning? Rarely needed here.
-It's not just about how much money you can save but about learning new habits that we all need to learn and pass on. Also not about if in Palo Alto it is all renewable. Think about the bigger picture.


 +   3 people like this
Posted by Sherry Listgarten, a Almanac Online blogger,
on Oct 12, 2020 at 4:48 pm

Sherry Listgarten is a registered user.

@MM, thanks. I agree that OHM Connect is great, but it requires a "smart meter", which most residences in Palo Alto don't have. Hopefully that will change in the next year or two.

Yes yes yes, we need to learn the right habits and model them for our kids. It's hard to know what those are sometimes. Take dishwashing. I used to hand wash, but it uses more water than a dishwasher (so I'm told). So I switched. What's right?

I remember being taught how to wash dishes in Home Ec. The teacher had us putting a bucket in the sink, filling it with soapy water, then washing in a prescribed order, with glasses first and pots last. She was trying to teach us a good habit -- dishwashing that conserved water.

BTW, is line drying really easy? It seems to me like it takes forever and the clothes come out crunchy. How do you do it?


 +   3 people like this
Posted by KOhlson, a resident of Old Palo Alto,
on Oct 12, 2020 at 10:38 pm

KOhlson is a registered user.

Sherry - not a stupid post. I liked reading it. But if most are like me (and perhaps you), they've replaced dozens of bulbs with LEDs and then a shinier object rolled by. I've been replacing them for years, and in some cases have replaced the first ones. Last month was 341 kw, but there's still more to go. Some for efficiency's sake, and some just because (CFL).


 +   3 people like this
Posted by Kristy, a resident of Menlo Park,
on Oct 13, 2020 at 10:56 am

Kristy is a registered user.

Great article, so much fun. Thanks for doing all the legwork for us.


 +   3 people like this
Posted by Sherry Listgarten, a Almanac Online blogger,
on Oct 13, 2020 at 11:12 am

Sherry Listgarten is a registered user.

@KOhlson, yowza, 341 kWh!! That is fantastic. You probably know, you only get charged 13.8 cents instead of 19.4 cents for the first 330 kWh, so your bill must be super low. I'd guess you are paying something like $50 for electricity, compared with my $135 or so ($110 without the EV). Congrats!!

BTW, speaking of $25 to drive the EV for the month, I wonder if people really understand how cheap EVs are to own and operate. No maintenance, but also just half the cost to fill up, plus you can do it at home at your convenience. They are so great.

Thanks Kristy :)


 +   6 people like this
Posted by Get the whole family involved., a resident of Another Palo Alto neighborhood,
on Oct 13, 2020 at 11:26 am

Get the whole family involved. is a registered user.

When our girls were in middle and elementary school, we made energy use reduction a family learning game. We had a family conversation over dinner about the spinning wheel and our energy bill. We talked about how this relates to turning appliances off when they are not being used and working together to replace bulbs and share ideas about how we could cooperatively reduce energy use by doing less laundry and dishwasher loads, unplugging electronics with vampire lights and clocks when not in use, that sort of thing.

We agreed to supplement the girls' allowance with savings we collectively "earned" by reducing their energy use and our utilities bill. The money went into their savings accounts (also a financial learning experience). Amazing results. Showers got shorter, lights were turned off when the girls left a room. Suddenly they were interested in gathering laundry for all of the bedrooms before they did a washload of their own.

Now they are adults out in the world. These learned behavior changes are practice and they are teaching their flatmates how to do it. Yay!


 +   3 people like this
Posted by eileen , a resident of another community,
on Oct 13, 2020 at 1:21 pm

eileen is a registered user.

re crunchy clothes from outdoor drying. I toss them in the dryer with low heat for about 5 minutes, then hang them out. Thanks for the tip on OHM Connect. I can take advantage of that since I have a smart meter.


 +   3 people like this
Posted by pestocat, a resident of University South,
on Oct 13, 2020 at 1:56 pm

pestocat is a registered user.

Sherry,
Tell us about what electric appliances you have. Your water heater is it gas or electric? Do you have an air conditioner, if so can you use it to also heat your house. Or do you have a gas furnace? Suggest switching all your halogen light bulbs to LEDs. Also suggest you install dimmer switches in most locations, except hallways or outside safety lights. One more thing, how about not using the dish washer. Lots of of ideas for you.
Take Care,


 +   3 people like this
Posted by Weifeng Pan, a resident of Midtown,
on Oct 13, 2020 at 1:58 pm

Weifeng Pan is a registered user.

Halogen bulbs do not make any sense.
But to make situation worse, the entire light fixture will need to be send to landfill if you were to replace halogen lights with energy efficient ones.


 +   4 people like this
Posted by Common sense, a resident of Mountain View,
on Oct 13, 2020 at 4:27 pm

Common sense is a registered user.

Weifeng Pan, a resident of Midtown, wrote: "Halogen bulbs do not make any sense. / But to make situation worse, the entire light fixture will need to be send to landfill if you were to replace halogen lights with energy efficient ones."

Some years back, halogen bulbs would have been considered progressive and desirable: they are more efficient sources of visible light than the incandescent bulbs formerly used almost everywhere.

Fluorescent bulbs (including compact fluorescents) are far more efficient than either. They also create a hazardous-waste problem that incandescent and halogen bulbs don't. LED lamps can be even more efficient than fluorescents, and also offer uniquely long lifetimes.

I'm not sure about the last point made by Wifeng Pan because the blogger mentioned availability of LED replacements that can fit in the same fixtures where she originally used halogen lamps.

It seems as if the number of sockets that can't be filled with LED replacement lamps shrinks almost daily.


 +   4 people like this
Posted by Ferdinand , a resident of Barron Park,
on Oct 13, 2020 at 5:03 pm

Ferdinand is a registered user.

Thanks for getting us calculating! Do you have any gas appliances? Curious how that feeds into your consumption. Here is ours...
- 2.6 kWH per day (when sunny/solar panels engaged and about 5kWH when it is cloudy/winter; we have an on-demand electric water heater)
- If we convert our gas consumption to roughly equivalent electricity that would be about 10 kWH avg per day (We have an old stove with pilot lights and a small sits on the floor gas space heater--came with our 1920s house and our only heating source). With kids in distance learning, our consumption will spike!
So I guess our total (with 4 peopls) is around 15kWH before distance learning!


 +   3 people like this
Posted by Sherry Listgarten, a Almanac Online blogger,
on Oct 13, 2020 at 5:58 pm

Sherry Listgarten is a registered user.

@WholeFamily: Amazing. That is exactly what we need, at home and in school. Thank you for sharing your approach.

@Weifeng: I've seen lots of new types of LEDs that are meant to replace halogen or other inefficient bulbs in their existing fixtures. For example, here is my old G9 halogen bulb on the right and my new LED G9 on the left.



It's a little bigger, but it fits fine in my fixture. For some fixtures I had to leave off a small glass protective shade above the bulb, but with the new cooler bulbs, I don't need it any more.

You can look things up on Amazon (e.g., "LED g9 bulb warm white") or ask in a local hardware or lighting store (e.g., Stanford Electric).

From what I can tell so far, the dimming works but not always smoothly. And one of my lights doesn't always turn on right away now. So this transition is still a work in progress. But it's important since so much of our use comes from lighting.

@Ferdinand: That seems amazing. And you have solar to boot! I don't have solar, and I still have gas heat. My electricity use should be a lower for sure. I think it's mostly lights, so I'm going to work on those.

Thanks for the terrific comments and for sharing your stories!


 +   3 people like this
Posted by pestocat, a resident of University South,
on Oct 13, 2020 at 6:18 pm

pestocat is a registered user.

Sherry,
You are correct about dimmers for LED bulbs. Dimmer switches that worked for incandescent bulbs can be a problem for LEDs. I suggest you try Lutron's Maestro C.L dimmers. You can get these at Home Depot and on Amazon. As I was changing out my incandescent bulbs I had to switch to the Lutron dimmer.


 +   3 people like this
Posted by Sherry Listgarten, a Almanac Online blogger,
on Oct 15, 2020 at 12:09 pm

Sherry Listgarten is a registered user.

@pestocat, thanks for the pointer.

If helpful for anyone, here's another example of an LED (left) and halogen (right).


 +   4 people like this
Posted by R-1 res, a resident of Midtown,
on Oct 15, 2020 at 10:36 pm

R-1 res is a registered user.

I remember as a kid 60 years ago switching on all the lights in the house to see how fast I could make that wheel spin. Looking at my electric meter now (undoubtedly not the original) I note my Kh value is shown as 3.6 watt-hours per rotation, so I suppose my wheel spins twice as fast as yours at a given load.

What is that mysterious Rr = 13 8/9 number engraved above your dials? It is exactly 100 divided by your 7.2 Kh value. My meter says Rr = 27 7/9, or exactly 100/3.6 for my Kh value. I read somewhere that Rr means register ratio.

To me this indicates a series pair of 100-tooth worm gears driving that first readout dial. The four higher-order digits are geared similar to an old-fashioned car odometer.


 +   2 people like this
Posted by Sherry Listgarten, a Almanac Online blogger,
on Oct 16, 2020 at 11:08 am

Sherry Listgarten is a registered user.

Okay, that made me curious! Turns out Popular Science has a great writeup on how this kind of electric meter works, along with some photos like this one.



Among other things, it explains why the five dials up top don't all rotate in the same direction (which you probably knew), and also touches on the involvement of the older brother of Lord Kelvin (!) in the design of the gear mechanism.

P.S. The meter in the Popular Science writeup shows 7.2Kh but an Rr of 27 7/9. Tom Scogin's blog says Rr is "the worm gear ratio from the shaft of the spinner disc to the idler gear". He says the ratio of idler gear to least-significant digit is usually 100, but I guess in the Popular Science meter, it was 200.


 +   1 person likes this
Posted by Sherry Listgarten, a Almanac Online blogger,
on Oct 17, 2020 at 10:20 am

Sherry Listgarten is a registered user.

FWIW, here's another example of a halogen (on left) and two LED "equivalents", a 150W in the middle and a 300W on the right. You can see the size difference!


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