Wiring Thread: This stupid safety device started alerting that there wasn't safety!

The Something Awful Forums > Discussion > Hobbies, Crafts, & Houses > Wiring Thread: This stupid safety device started alerting that there wasn't safety!

Thermopyle: Jul 1, 2003; ...the stupid are cocksure while the intelligent are full of doubt. �Bertrand Russell

I keep confusing myself on this.

If I'm using CT sensors to measure current on a 220v appliance (heat pump water heater) for the purposes of estimating cost to run, do I need to measure both legs and add them? I think that's correct since I'm sure some components of the appliance are just 110v, but I'm not very confident in that.

# ¿ May 15, 2020 19:36

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# ¿ Apr 20, 2024 02:23

Thermopyle: Jul 1, 2003; ...the stupid are cocksure while the intelligent are full of doubt. �Bertrand Russell

angryrobots posted:

Measure both legs, and use the number from the higher leg (if one is higher) for instantaneous current usage..... But electricity consumption on that appliance in particular is very dependent on individual usage. For instance, if you regularly have heavy hot water use that bumps the unit out of heat pump mode into resistance heat.

If you want an accurate reading, you'll need to hook up a recording meter.

Yeah, I'll be recording the data over time.

Thanks for the info. Can you explain the reason it's the higher leg that should be measured?

# ¿ May 15, 2020 22:52

Thermopyle: Jul 1, 2003; ...the stupid are cocksure while the intelligent are full of doubt. �Bertrand Russell

angryrobots posted:

The higher leg will account for 120v load, and I do think that the condenser fans in those units are 120v - though they may be connected to maintain load balance as much as possible. Using the higher number is "close enough for engineering purposes" which I'm assuming is good enough for your test.

That being said, to accurately track kwh you need a voltage reference to go with your CT. I'm guessing you have a homebrew setup and aren't doing this because a standalone meter would come with CTs, voltage probes, and instructions on how to connect. But I guess you can get some idea of energy used, with some degree of usefulness?

I'm...not sure if it'd be good enough!

And yeah, it's a DIY setup with an Arduino and some CT clamps. I'm just wanting to figure out how much it costs to run.

# ¿ May 16, 2020 00:05

Thermopyle: Jul 1, 2003; ...the stupid are cocksure while the intelligent are full of doubt. �Bertrand Russell

angryrobots posted:

Me either!

I don't think you're going to answer the question that you want. Your setup could compare usage between the HP water heater and a standard resistance electric, but will not accurately give you kwh.

Are you looking at an existing installation considering getting one, or wishing to see how your heater compares with EPA estimates or....?

Existing installation.

I have multiple reasons and goals.

1. It's just interesting to know how much I spend on hot water.
2. I have my previous water heater hooked up and valved so that I can switch between the two. So, I want to see if and how much money is actually saved with the heat pump model. So, this'll be comparing the complex usage of the heat pump model with the simple usage of the resistive heater model.

# ¿ May 16, 2020 01:12

Thermopyle: Jul 1, 2003; ...the stupid are cocksure while the intelligent are full of doubt. �Bertrand Russell

kid sinister posted:

However, you got a bigger problem. You have backstabs. They kind of like to start fires.

I don't disagree with you, and I've told people the same thing. Multiple times I've seen them with scorch marks.

However, I'm wondering...do we have any sort of evidence on this other than anecdotes? It'd be nice to be able to tell people this with some more confidence.

# ¿ May 27, 2020 07:08

The Something Awful Forums > Discussion > Hobbies, Crafts, & Houses > Wiring Thread: This stupid safety device started alerting that there wasn't safety!