Designing a basic single element 120V/20A setup, question.

[jdudek]

Greetings!

I am working on putting together a basic EBIAB system with a 2200W element that would run off a 20A receptacle in the kitchen. I was wondering about the following. The controller I am looking to build would run the element, a couple of LEDs, a PID and a small pump (0.7A rating). When i collect the power ratings for everything from datasheets and add them all up, I am looking at 19.1Amp draw (max) when everything is on at the same time.

Is this getting dangerously close to the 20A capacity of the circuit? Could I experience any issue with any kind of current spikes. Or am I basically ok, as long as i don't run anything else off this circuit?

Thanks!

 

[bgmac]

Yes/No, you should only put an 80% load on the circuit so you are pushing it. The installed wire might generate an uncomfortable amount of heat (inside the wall) from old/poor connections etc... I wouldn't do it.

 

[jdudek]

Thanks fir the prompt answer... indeed a bit of googling shows that the "safe" load capacity is 80% of the rating. This is making me wonder about some of the commercially available turn key setups. For example, many available setups for 120V/15 amps come with a 1650W element. That's already 13.75A (>0.8*15=12) and that's not factoring anything else like a pump, which could easily add 1A or more, getting us very close to 15A.

Clawhammer sells such a 120V/15A setup, and I've seen some others. Seems as though these are operating on the edge...

 

[bgmac]

Thanks fir the prompt answer... indeed a bit of googling shows that the "safe" load capacity is 80% of the rating. This is making me wonder about some of the commercially available turn key setups. For example, many available setups for 120V/15 amps come with a 1650W element. That's already 13.75A (>0.8*15=12) and that's not factoring anything else like a pump, which could easily add 1A or more, getting us very close to 15A.

Clawhammer sells such a 120V/15A setup, and I've seen some others. Seems as though these are operating on the edge...

I think it means the Clawhammer system draws 15 amp which means you should run it on a 20 amp circuit or greater. Normally companies advertise how much their systems draw and not what size the circuit should be. There are some companies out there that give recommended minimum circuit amperage. Blichmann is one of them.

 

[jdudek]

The specs on the website for their 120V controller states:

• Designed for up to a 1650 watt element
• Uses a standard 15amp 120v outlet

it comes with a 15A plug as well, so it's not designed to be used on a 20A circuit.

I wonder what their take is on this...

 

[bgmac]

The specs on the website for their 120V controller states:

• Designed for up to a 1650 watt element
• Uses a standard 15amp 120v outlet

it comes with a 15A plug as well, so it's not designed to be used on a 20A circuit.

I wonder what their take is on this...

There are many discussions about going up to 100% and 125% load on a circuit. Maybe if you have a dedicated outlet and you know that the wire and connections are good then you can push above 80%. But you will find that it is time dependent for a continuous load. You should only go so long to near 100% due to heat build up. On brew day, you don't want to be thinking like, can my circuit handle the load, while I start a fire, or having the breaker tripping on you every 15 minutes. Any good electrician will tell you to design for 80% or less circuit load. I run a 5000w element on a 30 amp 240v GFCI breaker with properly sized wire and don't even think about it when the element is cranked up to 100%. There are building code minimums, but I can tell you they cause headaches if it is built to just the minimum. Trust me, I can go on for hours that just the minimum code has caused.

 

[doug293cz]

The 80% rule applies to continuous loads, which by definition is more than 3 or 4 hours (can't remember which.) This has been discussed ad nauseum on HBT. With a brewing system, you will only be running at 100% power during heat up. Maintaining mash temp or boil will be significantly less than 100% power. I have not seen any reports of brewers having problems with systems that operate near, but below, the circuit rating, and I would have no qualms about doing so.

Edit: The 12AWG wire required in a 20A circuit has a resistance of 0.0016 ohms/ft. Power in a wire is given by P = I^2 * R, so at 20A the heat generated per foot is 20^2 * 0.0016 = 0.64 W/ft. Since the same current flows in the hot and neutral wire, the total heat generation at 20A is 1.3 W/ft. Unless you coil the wire, you can't get much heat rise from 1.3W/ft, even in an insulated wall.

Brew on

 

[Bobby_M]

The 80% rule applies to continuous loads, which by definition is more than 3 or 4 hours (can't remember which.) This has been discussed ad nauseum on HBT. With a brewing system, you will only be running at 100% power during heat up. Maintaining mash temp or boil will be significantly less than 100% power. I have not seen any reports of brewers having problems with systems that operate near, but below, the circuit rating, and I would have no qualms about doing so.

Edit: The 12AWG wire required in a 20A circuit has a resistance of 0.0016 ohms/ft. Power in a wire is given by P = I^2 * R, so at 20A the heat generated per foot is 20^2 * 0.0016 = 0.64 W/ft. Since the same current flows in the hot and neutral wire, the total heat generation at 20A is 1.3 W/ft. Unless you coil the wire, you can't get much heat rise from 1.3W/ft, even in an insulated wall.

Brew on

Agree. When is this 80% load BS going to die?

 

[Bobby_M]

Greetings!

I am working on putting together a basic EBIAB system with a 2200W element that would run off a 20A receptacle in the kitchen. I was wondering about the following. The controller I am looking to build would run the element, a couple of LEDs, a PID and a small pump (0.7A rating). When i collect the power ratings for everything from datasheets and add them all up, I am looking at 19.1Amp draw (max) when everything is on at the same time.

Is this getting dangerously close to the 20A capacity of the circuit? Could I experience any issue with any kind of current spikes. Or am I basically ok, as long as i don't run anything else off this circuit?

Thanks!

A dedicated 20amp circuit with properly sized wire and breaker can handle 20 amps indefinitely. It's also 100% code as long as the controller is plugged in to a receptacle instead of hard wired.

 

[jdudek]

Doug, Bobby, thanks for your answers. Especially thank Doug for the bit of math about heat in the wire, nice clean explanation.

I am an EE, but never trust an EE when it comes to electricity (except Doug) Most of us write verilog all day long and have long forgotten what voltage and current is. I do remember doing well in the power class though.... 20 years ago.

 

[day_trippr]

lmao!
One can only wonder what you've left in your career's wake

It seems actual understanding of electricity and how to control it has become an aside wrt gaining an EE degree. I recall around 2006 overhearing a young lady who was lamenting she didn't know the difference between a resistor and a capacitor.

Listening to one of her peers try to explain "the wiggly resistor symbol means the electrons lose energy following the bends" and "the capacitor symbol means the electrons have to leap across the gap" left me with my head on my desk...

Cheers!

 

[Ahks]

I’ve been brewing on a dedicated 20A circuit with one of Bobby’s 2200 w elements and 12v dc pump for a few years now. No problems at all. At some point I borrowed an ir thermometer from the Engineering Dept at work and it only reads a few degrees warmer than ambient while ramping to mash in or to boil. Tested on the plugs and the drop running in my basement ceiling.

 

[odie]

I have a single 1650 watt element (110v/15a) wired to a simple heavy gauge power cord. no problems with it running constantly for several hours.