RIMS Question

[jgonzo108]

I have been doing alot of reading and have decided on building a simple RIMS setup. After reading several threads on this forum, I decided on using a 5500 watt element run on 120v as my heat source. My question is this, What size breaker would be sufficient to run the RIMS Tube safely? I was planning on using this kit as a base for my controller:

http://www.ebrewsupply.com/shop/ebrew-kits/ebrew-pid-kits/20a-rims-kit.html

I have no plans, at the moment, to upgrade to a full electric system so would this controller kit be sufficient? I see in the description it says up to 2000w element. Or would this kit better suit my needs?

http://www.ebrewsupply.com/shop/ebrew-kits/ebrew-pid-kits/1-pid-30a-biab-kit.html

Thanks

 

[Bobb25]

I know nothing about RIMS systems, but from an electricians standpoint, 5,500 watts running at 120 volts is 46 amps, or a 50 amp breaker with some big wire. I would guess that this size heating element is usually run on a 240 volt, 30 amp circuit.
Bob

 

[jpalarchio]

If the 5500w element is 240v which I suspect it is, that's 1375w at 120v and around 12 amps.

 

[Bobby_M]

Yup, 12 amps. Honestly, that kit linked is overkill for what you're trying to do. You need a PID, SSR, heatsink, RTD or TC, and a project box. If you want a positive disconnect, you just need a SPST switch that can handle 15 amps.

 

[jgonzo108]

Thanks for the info. Will keep you guys posted as the project progresses.


Sent from my iPad using Home Brew

 

[schematix]

!!! VERY IMPORTANT !!!

A circuit breaker is to be sized for 125% of continuous load + 100% of non-continuous load (per NEC). The definition of continuous is a little gray, but is typically accepted to be for 60 minutes or more. The reasons for this requirement are many, but too much to detail here.

Practically speaking, that means you want to pick a 15A CB, and choose wire capable of sustaining 15A, which means at least a #14AWG copper. Additional de-ratings may apply depending upon exact usage.

I also want to remind about the purpose of a circuit breaker because it is commonly misunderstood. A circuit breaker is NOT designed to protect a device (or you!) in the event of an over current. A circuit breaker is designed to protect the WIRE from damage due to an over current. When wire is subjected to high current loads it rapidly heats and will undergo irreversible physical changes, which can significantly increase the risk of a fire.

Your standard household circuit breaker is known as a thermo-magnetic type. That means it has 2 ways to trip. The magnetic trip functions to rapidly open the circuit in the event the current exceeds a certain multiplier of the rated current for a very short duration (milliseconds). This is known as the characteristic trip curve, and can be chosen. 7-10x rated current are common. The other function is thermal, and is based on a complex time-vs-current relationship. This functions relatively slowly (typically minutes) compared to the magnetic trip. You can run a 15A circuit breaker at 20A for quite a while before it trips due to the thermal limits (depends on the exact unit and its curve). The magnetic limit will never be reached at that level.

Your device may not like 33% over current for that long. If that's a possibility, you may want to consider using what is known as supplementary circuit protection IN ADDITION to a circuit breaker. It is kinda like a circuit breaker, but isn't really a circuit breaker. However, it can be used to protect a device (but not the wire!) from significant damage.

 

[atoughram]

A Continuous load is defined by the NEC as "Continuous Load. a load where the maximum current is expected to continue for three hours or more." Article 100 "Definitions" 2011 NFPA 70. Since a RIMS relies on a PID that pulses the load, the load is not continuous. Also, I'm not sure anyone mashes for three hours or more.

 

[schematix]

A Continuous load is defined by the NEC as "Continuous Load. a load where the maximum current is expected to continue for three hours or more." Article 100 "Definitions" 2011 NFPA 70. Since a RIMS relies on a PID that pulses the load, the load is not continuous. Also, I'm not sure anyone mashes for three hours or more.

Thank you for the clarification with a specific citation.

The PID could deliver 100% power in the case of stepping, or an undersized element. But yes, doubtful for 3 hours unless you're making a bud light clone.

I'd look at the trip curve for the selected circuit breaker size and make sure you're not marginal.

 

[jgonzo108]

Well did the build for my control panel. Will post more pics in the near future.