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Old 08-28-2009, 09:15 AM   #1
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REVIEW - Powermeter Pro to Visualize Generator Usage


A few weeks ago my buddy helped me install a 240 Inlet Box for my portable generator so I could power my house when the electricity's out. I purchased a 240 Volt AC, 30 Amp inlet box and attached it to a pre-existing 240 line which was running back to my electrical panel. The line was intentionally left behind when I moved my air conditioning system (system was too far away from air handler... whole different operation).

It was a fun project and I was surprised to learn just how much I could actually run off my 8000 watt generator... including my 4 Ton AC unit, a frige and my 60" plasma TV/Dish Network receiver. Not to mention a few lights and other odds and ends. However I was really disappointed in the fact that I couldn't visualize how much draw I was pulling off my generator. I thought it would be nice if there was some device close to my breaker panel to see this information in real-time. Sooo after asking around on this great forum I was led to the Powermeter Pro which is sold by nooutage
http://www.nooutage.com/e140132-5.htm.
This comes in particularly handy because most people I talk to tell me to "just do the math" by going around and adding up all the devices I intend to use. However, I quickly discovered that not only was that a pain in the butt but not very practical either. When the generator is feeding power to everything on a particular breaker, it's very difficult to add up the ceiling-fan or alarm clock which you forgot to turn off. This meter is also very handy when you have multiple devices running like the AC, frige, and several lights... instead of guessing whether you have enough juice to run your TV you can simply look at the meter (maybe it's at 50%) then go turn on your TV and then check it again (now at 60%)... no problem.

This device is fantastic and works exactly as described. Everyone here was a great help as well as the guys at noouttage. Thank you for patiently answering all of my stupid questions.

Since everyone was so helpful here at DIYchatroom I thought I'd contribute a little review outlining the installation process and my initial results.


This installation meets code requirements in Florida. I hear about people who feed generators through the dryer vent which is extremely stupid and dangerous... it's not the generator operator who gets hurt it's the kids playing around. Anyway, this setup didn't cost very much more and is the safe way.

Let me start by saying that I'm not an electrician...







The generator safety plate can be purchased online and negates the need for a sub-panel. It also allows you to run every breaker (not at the same time - limited by your generators output) instead of the few chosen ones in an expensive sub-panel. The bracket simply prevents the Main and Generator Breaker from being On at the same time. I understand that they make a bracket for every panel. Mine was made by Square-D for my Square-D panel.





















I can't remember for sure if I had both of my refrigerators on... maybe it was just one. I don't remember if I threw that breaker or not... hummm???



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Old 08-28-2009, 09:45 AM   #2
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REVIEW - Powermeter Pro to Visualize Generator Usage


Looks good and helpful tutorial style. You should host it on your own site too.

Little issues though:
1. I think on those square D breakers when you double lug wires, you are supposed to put one one each side of the clamp plate, not both on the same side.
2. I am also not sure if you are allowed to double lug a #10 wire with a #14 like that... Check the UL listing to be sure or it might be printed on the sticker on the door of the panel.
3. Does the meter need to run off 240v like you have it?
4. You used a white wire as a hot... you should paint the ends black with a sharpie marker.

All in all pretty minor issues. Good job!

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Old 08-28-2009, 11:22 AM   #3
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REVIEW - Powermeter Pro to Visualize Generator Usage


And of course there is conduit between that box & panel?
I'm not sure drilling the side of a blue box meets code

Nice setup
Is the meter on the 1st floor - no basement?
My panel is in the basement
So I'd want to have one upstairs where I could check it
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Old 08-28-2009, 01:17 PM   #4
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REVIEW - Powermeter Pro to Visualize Generator Usage


Quote:
Originally Posted by Scuba_Dave View Post
And of course there is conduit between that box & panel?
I'm not sure drilling the side of a blue box meets code

Nice setup
Is the meter on the 1st floor - no basement?
My panel is in the basement
So I'd want to have one upstairs where I could check it

HA! That's funny... there definitely might be a code issue with my entry point to the breaker box. It only had 2 inches to travel so I wasn't exactly sure how to do that. I basically just drilled through the stud and popped out a slug in the breaker box. Referring to the "meets code" comment, I was primarily refereeing to the delivery of the generator's power into the house. - if code inspectors are out there... I live at 44 Plato (moon crater) just past Campanus.

At any rate, I've heard of others running the device from their breaker box to their kitchen. One person even installed one inside their pantry (central area). My garage is close to the kitchen in my single level home. The instructions have a list explaining the distance limitations with different wire gauges. All sizes are over 100 feet.
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Old 08-28-2009, 01:26 PM   #5
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REVIEW - Powermeter Pro to Visualize Generator Usage


Quote:
Originally Posted by deeze View Post
HA! That's funny... there definitely might be a code issue with my entry point to the breaker box. It only had 2 inches to travel so I wasn't exactly sure how to do that.
You could use a threaded nipple.
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Old 08-28-2009, 01:59 PM   #6
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REVIEW - Powermeter Pro to Visualize Generator Usage


Quote:
Originally Posted by Gigs View Post
You could use a threaded nipple.
I could definitely use a threaded nipple... is that a drink?
Or does my wife need to be involved?

Seriously, should I just undo the wiring and jam that in the hole between the two boxes? Not sure if it would fit but I could always route out the stud a little more I guess. What exactly is the code issue? -what is the danger of leaving it as is? (curious)
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Old 08-28-2009, 02:07 PM   #7
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REVIEW - Powermeter Pro to Visualize Generator Usage


Quote:
Originally Posted by deeze View Post
I could definitely use a threaded nipple... is that a drink?
Or does my wife need to be involved?

Seriously, should I just undo the wiring and jam that in the hole between the two boxes? Not sure if it would fit but I could always route out the stud a little more I guess. What exactly is the code issue? -what is the danger of leaving it as is? (curious)
It's not much of a safety issue, but loose wires like that should go through a fitting into conduit. If it were romex then the only issue would be the fitting.

The sheet metal edge could possibly cut into them... that's the only real safety issue I see in terms of that.
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Old 08-29-2009, 11:59 AM   #8
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REVIEW - Powermeter Pro to Visualize Generator Usage


That's actually a very good thought... the edge is very sharp where I removed the slug. I better address that.
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Old 08-29-2009, 01:41 PM   #9
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REVIEW - Powermeter Pro to Visualize Generator Usage


I find it interesting that your 8kW generator is able to run a 4-ton A/C unit.

I would like to know the nameplate information from your A/C unit:
  • Full-Load Amps (FLA)
    Locked-rotor Amps (LRA)
    Min Circuit Ampacity
    Max breaker size

I am trying to size up a generator for my whole house, and they are trying to sell me a 20 kW unit. I believe that is way too large for my needs, but it is the starting amps from my A/C unit that is the stumbling block. Mine is only a 3 ton, but the starting Amps (LRA) is over 80.
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Old 08-29-2009, 01:57 PM   #10
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REVIEW - Powermeter Pro to Visualize Generator Usage


Quote:
Originally Posted by kbsparky View Post
I find it interesting that your 8kW generator is able to run a 4-ton A/C unit.


I would like to know the nameplate information from your A/C unit:
  • Full-Load Amps (FLA)
    Locked-rotor Amps (LRA)
    Min Circuit Ampacity
    Max breaker size
I am trying to size up a generator for my whole house, and they are trying to sell me a 20 kW unit. I believe that is way too large for my needs, but it is the starting amps from my A/C unit that is the stumbling block. Mine is only a 3 ton, but the starting Amps (LRA) is over 80.

Hey kbsparky, I'll run out and check my unit when it stops raining. I thought the same thing... I figured there was no way it would handle it but turns out it handles it easily. Now I do have a device called a "jump start" or something. After he installed it my lights no longer dim when AC initially turns on (if that makes sense). It was inexpensive... maybe $60. I also have a variable speed air handler... but it's massive. At any rate, I'll get that info for you. My generator is an 8000/13000.
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Old 08-29-2009, 02:00 PM   #11
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REVIEW - Powermeter Pro to Visualize Generator Usage


Quote:
Originally Posted by kbsparky View Post
Mine is only a 3 ton, but the starting Amps (LRA) is over 80.
Get a soft start kit?

Or, ask the A/C manu. for the minimum voltage at the unit that will reliably start the compressor.
With 240/216vac in from the panel and 50' of #10 copper from your PoCo this voltage will drop ~ 10vac, down to ~230/206vac. You might be able to crank up the generator voltage slightly to compensate for this. CFLs in your house won't mind the higher voltage as much as incands.

If the minimum starting voltage at the unit is 180vac and it's pulling 80A and the generator is set at 240v, the wire resistance plus the internal impedance of the generator must be less than 0.75 Ω. It's a series circuit: 180/80 = 2.25 Ω in series with 0.75 Ω in series with 240vac, conducting 80A for a few hundred milliseconds.

You need to know the gen's transient response.
http://www.yanceybros.com/index.php/...nts_corner/550

Last edited by Yoyizit; 08-29-2009 at 02:34 PM.
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Old 08-29-2009, 02:52 PM   #12
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REVIEW - Powermeter Pro to Visualize Generator Usage


My A/C unit was installed new, this past winter when we upgraded from an old 10 SEER system to a new 18 SEER heat pump. It's still under original warranty, so I don't want to jeopardize that status.

Whenever the compressor starts, my computer's UPS box bleeps from the voltage sag. The old unit never did this. Of course, I understand that these newer energy-efficient units require much more starting current than the old ones did, hence the momentary voltage sag.

I'll ask the fellow who installed it, if it contains a soft start kit, or is capable of having one installed, without affecting the warranty.

I was considering a 13 to 15 kW generator unit for my house, but when I told the dealer of my starting Amps for the heat pump, he tried to sell me on a 20-25 kW unit. I really think that a 13kW unit should be able to start this thing, and I sure don't want the fuel consumption of a unit almost twice that size if I don't need it.
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Old 08-29-2009, 03:51 PM   #13
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REVIEW - Powermeter Pro to Visualize Generator Usage


There was a poster who had gen/HVAC problems for months because a dipswitch on the HVAC control board was set incorrectly.

You might also now have a bad connection in your house. Pulling 10A from any outlet should give less than a 3v drop at the outlet and pulling 20A @ 240 should drop the 240 by ~0.4v measured at the panel.

13kw is 54A at 240v; I'd think that could easily handle 80A for one or two seconds. You maybe should get some other opinions and post specs.

Last edited by Yoyizit; 08-29-2009 at 04:44 PM.
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Old 08-29-2009, 09:45 PM   #14
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REVIEW - Powermeter Pro to Visualize Generator Usage


20kw seems like overkill to me as well. My gen is only a 5.5kw and I run well pump, 2 lighting circuits, entertainment center, fridge, and chest freezer on it with no problems at all.

If you have all your electronics on a UPS anyway, the voltage sagging when the heat pump comes on probably isn't a big deal. As long as it doesn't stall the generator, you are good to go.

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