two 5500 watt elements on 50 amp breaker?

[stevehaun]

My ebrewery runs off a 50 amp, 240 vac gfi breaker. My BK is a 55 gallon ss drum with two 4500 watt elements. I also have one standard march pump, two pids, the coils from 3 contactors, and 3 indicator lights running on the circuit. Do you think I could change the elements to 5500 watt without nuisance trips of my 50 amp breaker?
The 5500 elements would each pull 22.9 amps and the pump, pids, contactors and indicator lights should be well under 3 amps. So I should be under 49 amps - is this cutting it too close??
I guess another option would be to use one 4500 watt and one 5500 watt element. That would keep me under 45 amps.

 

[EarthBound]

Are the two 4500 W elements not providing heat quick enough?

 

[stevehaun]

I make 35 gallon batches and start with 43-45 gallons of wort at the beginning of the boil. It takes a while to go from mash temps to boiling then I ramp back to 90% power for the rest of the boil. I am successfully brewing with two 4500 watt elements but an extra 2000 watts would be nice.

 

[Lucky_Chicken]

What is the actual voltage at your outlet? If you actually have 240 then your amp numbers are good if you actually have 208 or 220 then you should be fine to go with 2-5500W elements because your amp draw will be lower.

 

[Lucky_Chicken]

FWIW my outlet has 243V... they vary a lot based on distance from the transformer.

 

[stevehaun]

I checked the voltage at the outlet and it measured 231 vac. If I recalculate using 231 amps, each element should draw about 22.06 amps and each element should put out about 5095 watts of power. This gets me to about 46-47 amps which is still cutting it close. Next time I have to replace elements I will replace with one 4500 and one 5500.

 

[thargrav]

Look at the voltage the 5500 watt elements are rated at - if 220V then they are rated to draw 25 amps at 220V.
5500W / 220V = 25A

This also means that at 231V they will draw 26.25A because heating elements are really just big resistors and what they draw is directly related to the voltage applied.
25A/220V*231X = 26.25A.

You also need to consider surge current - elements draw a little more when they are cold.

 

[stevehaun]

Thargrav:
It is a little more complicated. I am not an electrician or an EE but this is my understanding of how this works. Hopefully, more knowledgeable folks will correct me if I am wrong. The elements are rated at 5500 watts at 240 vac.
Heating elements are resistors and the resistance across them does not change.
Resistance of a 5500 watt element at 240 vac = voltage squared/P = 240 X 240/5500 = 10.47 ohms
Current for 5500 watt element at 231 vac = voltage/resistance = 231/10.47 = 22.1 amps
Likewise, at 231 vac they will only produce 5095 watts of power
Power = voltage squared/resistance = 231 X 231/10.47 = 5095 watts

 

[kal]

Haven't looked at Steve's math but the principle is correct. As the voltage drops the power will drop. The 5500W power rating is what you should get (give or take since they're not precision instruments) if the voltage is 240VAC. If voltage goes up, you'll get more than 5500W. If voltage goes down, you'll get less than 5500W. For brewing this doesn't matter.

Kal

 

[mabrungard]

I don't see this load working on a 50a circuit. With the 4500w elements, the continuous load is right around the 80% of the rated breaker capacity. That is good for continuous duty like would be experienced during the initial wort heating.

When that situation is bumped up with 5500w elements, the breaker may handle a brief load like this. But, it is unlikely to be able to handle that load on a continuous basis.

You're going to have to upgrade the breakers and wiring to handle twin 5500w elements.

 

[thargrav]

Thargrav:
It is a little more complicated. I am not an electrician or an EE but this is my understanding of how this works. Hopefully, more knowledgeable folks will correct me if I am wrong. The elements are rated at 5500 watts at 240 vac.
Heating elements are resistors and the resistance across them does not change.
Resistance of a 5500 watt element at 240 vac = voltage squared/P = 240 X 240/5500 = 10.47 ohms
Current for 5500 watt element at 231 vac = voltage/resistance = 231/10.47 = 22.1 amps
Likewise, at 231 vac they will only produce 5095 watts of power
Power = voltage squared/resistance = 231 X 231/10.47 = 5095 watts

Steve,

You are absolutely right. I did not know that the wattage rating was at 240V & was just commenting that if it were rated at 220V then the wattage would be higher.

But Martin's comment is also correct. I was trying to make the same point but I was too wrapped up in the math to make myself clear. You need to stay at two 4500 watt elements.

 

[camaro21]

Is throwing one element on a separate (new or existing) breaker not an option? I dont know how much of a pain that would be to run wiring to wherever you are brewing though

 

[thargrav]

Sure, and for the small wattage gain he's looking for he could run a small element off a heavy duty extension cord.

 

[Bobby_M]

Ohm's Law for dummies (and I mean that in the most endearing way possible)

watts/voltage = current:
11000w / 240 = 45.83a

voltage/current = resistance (ohms)
240v / 45.83a = 5.24 ohms (fixed)

Using it backwards, voltage/ohms = current and then voltage x current to get back to watts:
If you have 220v then it's 220v / 5.24 ohms = ~42 amps and that x 220v = 9237 watts.

So, whether you have 220v or 240v or somewhere in between, yes two 5500w elements will be fine on a 50a breaker.

If breakers are rated at a "duty cycle", it has to do with how many on/off or on/trip/resets it will go through before failure rate goes up.

The 80% rating people typically refer to is only based on breakers that feed branch circuits and if I understand it correctly, it's based on the fact that you might have a bunch of 15a capable outlets on a single 15a circuit and breaker.

In our use, we know exactly what the max load is and when it's being used.

I'm not an electrician, obviously. Don't listen to me.

 

[stevehaun]

Bobby:
That is the way I am looking at it. I am not worried about the 80% rule although I initially designed my panel that way. I started out making 15 gallon batches and morphed into 35 gallon batches. I just don't want to be close enough to 50 amps to have nuisance trips on brewday. I think the extra stuff (pump, 3 contactor coils, 3 indicator lamps, and 2 PIDS) on my panel amounts to less than 3 amps but I am not certain. I don't want to find out that I am tripping my breaker with 43 gallons of wort in the BK. I have changed my elements on brewday once and hope to never do that again. I may use one 4500 watt and one 5500 watt element which gives me an extra 1000 watts or 11% more power and at 240 vac keeps me under 46 amps (19 + 23 + 4 ).

 

[Spring_Chicken]

How long is it taking you to get to boil with the 4500's?

How long did it take with 15 gallons?

 

[stevehaun]

Doing the math, with 20 gal of wort I get about 2.8 F/min and with 43 gallons of wort I get about 1.3 F/min. So with 20 gal, about 20 min and with 43 gallon about 45 min. That said, I batch sparge and while collecting the first runnings, I turn on the elements as soon as they are covered. Even with a 35 gallon batch, the first runnings are boiling before I start pumping the second runnings into the BK. I have never timed it but I probably am boiling within 15-20 min of completing my sparge. With a 15 gallon batch, the wort was boiling by the time the sparge was completed.

 

[Bobby_M]

If you did have trips, it would probably only happen if both elements were firing at the same time and then both pumps were triggered at the same time. If they started even staggered by 1 second, it would help.

 

[shroomzofdoom]

I seem to remember someone saying that pumps draw a few more amps and surge at startup so he had to start pumps before starting the element. Though I never measured this myself, a current clamp or voltmeter would tell you the peak draw if you have an exposed lead you can work with.

 

[JLo]

I run 2 5500W elements off of one 50A 240V feed. One for my HLT and one for my BK. when I'm doing back to back batches I run them together for at least 30 minutes.

The first time I ran them together for two hours in a test, walked around with an amp meter, felt for wires and breakers that might be warming up. When I used to run a giant Christmas light display, I would make all of these calculations and worry about it.

NOTE: For my situation with the voltage I have in my house with my wiring on my brewing rig, my wife I am comfortable that we are safe operating the brewery at max draw for extended periods of time.

If I had old wiring and was unsure as to whether or not my actions would cost my family our house then I would seriously think twice about it. Just my 2¢

 

[Spring_Chicken]

I run 2 5500W elements off of one 50A 240V feed. One for my HLT and one for my BK. when I'm doing back to back batches I run them together for at least 30 minutes.

How long does it take to get 10 gallons up to strike temp with one 5500W element?

 

[thargrav]

Everything electrical draws a initial surge current when it starts, even your heating elements. But motors draw a lot - some even draw 10X or more at start-up. Breaker manufacturers know this and they design accordingly. Breakers all have a built in time or surge delay to accomodate startup surges.

Most breakers are not rated for heavy motor start-up surges - they will be marked "not for inductive loads". The pump motors we run are relatively small compared to the heating elements and it's probably not a concern unless you are already running very close.

 

[JLo]

How long does it take to get 10 gallons up to strike temp with one 5500W element?

I don't know, I run a HERMS system where I usually have 11 gallons in the MLT and 15 in the HLT. It is usually ready to go by the time the tanks are filled and I'm done fighting with my grain mill. Although I'm getting a Monster Mill next month. I only use the HLT element for now, but once I fix my mill issue I plan on heating 15 in the HLT with 5500W and 10/11 in the BK to reach strike temps.

 

[thargrav]

I seem to remember someone saying that pumps draw a few more amps and surge at startup so he had to start pumps before starting the element. Though I never measured this myself, a current clamp or voltmeter would tell you the peak draw if you have an exposed lead you can work with.

Everything electrical draws a initial surge current when it starts, even your heating elements. But motors draw a lot - some even draw 10X or more at start-up. Breaker manufacturers know this and they design accordingly. Breakers all have a built in time or surge delay to accomodate startup surges.

Most breakers are not rated for heavy motor start-up surges - they will be marked "not for inductive loads". The pump motors we run are relatively small compared to the heating elements and it's probably not a concern unless you are already running very close.