Pump Amps/Relay

I'm working on designing the HERMS part of my system right now. I currently have a 30 Amp GFCI circuit that I'm going to use with this, giving me 24 working Amps
I plan on using a 4500W 240V element which will draw around 18.75 amps leaving me with 5.25 for the panel and the pump.

I'm planning (don't have yet) on using a 3-MD-HC for the pump which draws 2.4 amps. What I'm not sure of is whether it will use more on startup which may trip the breaker. Anybody have comments suggestions on this.

Secondly, I'm planning on controlling the pump with a simple on/off switch hooked to mechanical relay or a contactor; not really sure which is the correct/better way. I was hoping somebody could give me opinion/fact on which is the way to go and based on the first question, how big of a XXX do I need to get the job done.

Thanks,
Eric

That pump uses about 8A on startup.

You have 30A avail, 19A going to the element, 8A going to the pump on startup so you are only at 27A.... then dropping to about 21-23A. If you are worried about it, you can use a March pump, they draw about half the LG, or you can Appollo 13 the thing and start the pump at the beginning of the session, leave it running, and then cycle on and off your element.

You aren't limited to 24A... that is sort of a misnomer. The 80% load rule applies at constant loads for 3 plus hours or something.

You have 30A avail

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I forgot that I can use the whole 30 as long as it's not continuous, right?

8A going to the pump on startup

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How long does the pump draw that 8A for?

you can use a March pump

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From my reading, it seems that the March is the way to go. I wonder what the current draw for the LG are if I wire 220? 1.2A while running - so 4A at startup?

leave it running, and then cycle on and off your element.

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I was planning on running the pump for the entire mash session.

Even if you start the pump, while the heating element is on, you are under 30A, so I don't see it making a big difference. It will only draw that load for like... 1 second maybe? Only as long as the pump takes to spool up, which isnt long at all.

I dont think you can take a 120VAC pump and just wire it for 220VAC though

egurney said:

I'm planning (don't have yet) on using a 3-MD-HC for the pump which draws 2.4 amps. What I'm not sure of is whether it will use more on startup which may trip the breaker. Anybody have comments suggestions on this.

Secondly, I'm planning on controlling the pump with a simple on/off switch hooked to mechanical relay or a contactor; not really sure which is the correct/better way. I was hoping somebody could give me opinion/fact on which is the way to go and based on the first question, how big of a XXX do I need to get the job done.

Eric

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Is this pump 240V? If so, you should be fine with the breaker. If it is 120v, you will be loading only one leg and may trip the breaker at startup.

You should be able to just use a switch. A standard toggle switch will work (a 2-pole for 240V). You would only need the relay if you are connecting the pump to controller of some sort.

FWIW I have been drawing 40.3A off a 50A breaker and started an LG and it didn't trip the breaker... FWIW

Is this pump 240V?

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Don't have the pump yet. Maybe I should upgrade my circuit to 50A? I eventually want to do my boil electric too and was hoping to use a 5500W element, which would really be pushing it!

You should be able to just use a switch.

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Damn I'm overthinking this stuff!

If you can easily, which is sounds like you can... go 50A. This will give you wiggle room for the larger element and pump and peripherals. You will pay $20 more for the breaker, but have more peace of mind.

You will pay $20 more for the breaker

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Time to start combing ebay for a breaker! Probably cheaper to replace my subpanel with a spa panel from HD or Lowe's

egurney said:

Time to start combing ebay for a breaker! Probably cheaper to replace my subpanel with a spa panel from HD or Lowe's

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Yes, $60 or so compared to $100 or so for the breaker

Yes, $60 or so compared to $100 or so for the breaker

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Of course, either was I'll need to run new 6G wire, which ain't cheap either. Wonder where I can get that cheap!

egurney said:

Of course, either was I'll need to run new 6G wire, which ain't cheap either. Wonder where I can get that cheap!

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Aluminum is an option for a feed. Generally step up one size from copper. Look for SER cable. I know it is available in #4 and may be cheaper than #6 copper.

Any idea what I should be paying per foot for 6/3 copper wire?
Looks like I can get 90' online for $165 shipped:
http://www.drillspot.com/products/573642/southwire_company_63950072_90_6_3_w_g_nmb_cable

egurney said:

Any idea what I should be paying per foot for 6/3 copper wire?
Looks like I can get 90' online for $165 shipped:
http://www.drillspot.com/products/573642/southwire_company_63950072_90_6_3_w_g_nmb_cable

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That doesn't seem like a bad price. I just paid 1.80/ft from electrical supplier. Do compare aluminum SER though. You may save a few bucks.

[edit] just checked, I can get aluminum 4-4-4-6 SER for $0.77 per foot. Less than half the price! Use inhibitor on your connections and you will be fine.

just checked, I can get aluminum 4-4-4-6 SER for $0.77 per foot. Less than half the price! Use inhibitor on your connections and you will be fine.

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I'll look into it, but for some reason feel more comfortable with the copper...

egurney said:

I'll look into it, but for some reason feel more comfortable with the copper...

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It seems many people do. But, believe me aluminum feeders are used quite alot. We are wiring a 26 unit apartment building now and every apartment feed is aluminum. As long as you terminate properly, it will be fine. You may even have aluminum conductors feeding your meter on your house right now around here about half are done that way.