Power "In" Question...

Hi All,
I've been reading a lot lately and have been planning my control panel build that will utilize (1) 208-240v/4500w element, and 2 march type pumps.
Of everything I have read so far, the normal setup to use a dryer plug is a 30amp gfi protected circuit w/pid's/ssr's etc.

My situation is that I am renting a house and am designing my panel to be used in the basement.

In the main breaker box for the clothes dryer outlet, the existing dpdt breaker is listed as 220v/40amps non-gfi.

Finding 40 amp components is very difficult and expensive.

I would like to use a 30A Ground Fault Interrupt with Male Plug GFI Cord Cable
(seen HERE) and am wondering if I can use this without any problem. I have determined that total amperage draw would be no more than 25 amps if that at peak use.

I have thought of changing out the breaker for a gfi 30 amp but I don't want any issues to arise from the landlord...he lives across the street.

Thanks in advance for your input and suggestions...!
btw....i HATE renting!!!!!!

30A is less than 40A. You'll be fine putting the 30A stuff down line of the 40A breaker as long as you don't exceed the 30A rating in your system.
BUT 9000W (2x4500) on a 208V supply is 43.3 Amps. That will not work with your 30A or even 40A breaker. Even if you have a true 240V, 9000/240 is 37.5A, still not going to work. Even off the 40A breaker, you want to limit yourself to 32A (80% of max rating).

Thanks for the info IP...!
I'm only running (1) 4500 watt element in a 2 vessel brew setup. 2 march pumps as well.

I don't want to be a naysayer, but if you're going to run that cord you have to have 30A circuit protection before the cord. Basically, everything downstream of the 40A breaker has to be capable of carrying 40A safely until it hits 30A circuit protection. Imagine if something goes wonky and there is a short before your 30A protection. Now your cord is carrying 40A, because that's what the breaker upstream is letting it pull (assuming things are really wrong and that breaker hasn't tripped yet). Since the cord is only rated to 30A, but it's getting fed 40A, it could heat up, causing the insulation to melt and starting a fire or energizing something it touches if the insulation burns through. Obviously this is a worst case scenario, but it's one that you don't want to experience.

To be safe, either replace the breaker with a 30A (talk to your landlord first) or run a 40A cord to your panel and integrate the GFCI elsewhere.

Good point Trigger. Run a 40A cord from your breaker to a 30A breaker in a control box. Not sure if two breakers in line with each other would cause a problem with GFCI or not. I don't think so, but I'm not 100% on the specifics of how a GFCI works. There's a lot of discussion on it around here.

Thanks for the suggestions guys. I think I'll just replace the 40 amp breaker with a 30 amp and be done with it. Then I can use the 30 amp cord with the built in gfci without any worries. The clothes dryer is the only appliance being used on the circuit and is rated for 30 amps. Not sure why they installed a 40 amp breaker instead of a 30??

Thanks again!

You could definitely put a 30A breaker downstream of your GFCI, but it sounds like you're swapping breakers in the panel, so no issue there.

One thing to make sure of is that your dryer outlet is the 4 prong receptacle. If not you'll have to replace it to use that power cord, which may mean pulling new wire.