Breakers in control box

I just got my bcs 460 in and am about to pull the trigger on my all electric build. I have been reading on this forum for at least 4 months educating my self. I appreciate all the great builds and major props to Kal and PJ. This leads to my question.

I see that Kal doesn't use breakers in his control box and all the diagrams PJ makes calls for them. It is my understanding that both agree on using the spa panel and the power source. So what is the reasoning behind the two different builds, otherwise they seem pretty similar.

Thanks,
TJ

twallin,

I generally include breakers within the control panel if it is being fed with a 240V-50A circuit. If the feed is from a 30A source, the control panel breakers are not needed.

The breakers that I illustrate and place are for component protection.

P-J

twallin,

(An after thought) By the way, I've drawn a lot of diagrams that do not have breakers within the control panel. It is a "it all depends" situation.

What are you wanting to do?

P-J

Alternatively you can use fuses to protect components. That is what I do. It is cheaper, takes up less space, and serves the same purpose. The advantage of the breaker is you do not need to keep spare fuses around in case you blow something.

Boerderij_Kabouter,

Good point. However, a fuse will only open one leg of a 240V circuit leaving the device exposed to a possible deadly voltage (Yes.. I know - GFCI). A breaker will open both lines on a 240V circuit.

To each there own.

Just saying...

I have a related question regarding using the 50 amp spa panel (for its GFCI), fed from a 30 amp circuit breaker (no GFCI), using 10 gauge wire. As wired, that should be fine because the 30 amp circuit breaker is protecting the 10 gauge wire.

However, if moving the rig somewhere where there is 50 amp service, there is no longer adequate protection for the 10 gauge wire. So for safety a 30 amp circuit breaker (or fuses) should go somewhere. Would it be best in the spa panel (so it is upstream of the 10 gauge wire between the spa panel and the control panel), or in the control panel itself, or does it not matter?

Thanks.

Thanks for the responses. I was surprised to get a response from the "Man" PJ right away. Totally makes sense to run the breakers depending on power going in, and now I see why Kal uses the fuses.

I am building a bcs controller for a HERMS setup. I just want to run my two elements with the bcs and use switches in my panel for the 2 pumps. I am going to install a 50 amp breaker in my box, that will run to a 50 amp spa panel in my man cave. The system is going to run 2 5500 watt elements similar in setup to what Kal uses.

P-J said:

Good point. However, a fuse will only open one leg of a 240V circuit leaving the device exposed to a possible deadly voltage (Yes.. I know - GFCI). A breaker will open both lines on a 240V circuit.

Click to expand...

Only if it's a double pole breaker. Otherwise 2 fuses can be used. Same result.
EDIT: Actually, thinking about this some more, having a 2-pole breaker where both poles break if one goes into overcurrent is probably a bit safer because you're cutting both legs.

To the OP: On a 50 amp panel don't forget to add a 30A fuse or circuit breaker to each of the HOT lines inside the panel going to the element element receptacles. This is to protect the 10 ga wire inside the panel (and the element cords).

FWIW, two 5500W elements is 11000W which is 45.8A of draw on a 50A circuit. Depending on who you want to believe/trust and where you live, that's above the 80% load rule which is 40A. Most peopel will reduce the elements to 4500W or go up to a 60A circuit and parts.

Kal

P-J said:

Boerderij_Kabouter,

Good point. However, a fuse will only open one leg of a 240V circuit leaving the device exposed to a possible deadly voltage (Yes.. I know - GFCI). A breaker will open both lines on a 240V circuit.

To each there own.

Just saying...

Click to expand...

kal said:

Only if it's a double pole breaker. Otherwise 2 fuses can be used. Same result.
EDIT: Actually, thinking about this some more, having a 2-pole breaker where both poles break if one goes into overcurrent is probably a bit safer because you're cutting both legs.

To the OP: On a 50 amp panel don't forget to add a 30A fuse or circuit breaker to each of the HOT lines inside the panel going to the element element receptacles. This is to protect the 10 ga wire inside the panel (and the element cords).

FWIW, two 5500W elements is 11000W which is 45.8A of draw on a 50A circuit. Depending on who you want to believe/trust and where you live, that's above the 80% load rule which is 40A. Most peopel will reduce the elements to 4500W or go up to a 60A circuit and parts.

Kal

Click to expand...

Thank you P-J and Kal for all of your valuable input.

I've been trying to figure out a couple things mentioned in this thread and illustrated in a couple diagrams I've seen around HBT:
https://www.homebrewtalk.com/f170/just-another-electric-brewery-build-thread-317746/#post4038376
https://www.homebrewtalk.com/f170/trying-find-one-p-js-old-layouts-307766/#post3830891

The diagrams show 25A breakers to be mounted in the control panel. I assume the 25A breakers are simply for protecting the 10 gauge wire from short-circuit conditions, particularly for short-circuit current between 25A and 50A. Is this assumption accurate? If so, I would think that any short circuit conditions will result in more than 50A, tripping the 50A breaker. Would this leave the 25A breakers unnecessary?

Might 2 fuses per heater element be a better idea? If so, why and which fuses would you recommend?

I'm curious if any of the gurus can help me figure out how a single 4500 or 5500 w resistive element will draw more than 30a but less than the 50 needed to trip the spa breaker? I'm serious, not being snarky at all. I ask because i figure it is either going to be fine or a short. The short would trip the 50. I fully understand fusing the low current devices and contactor coils, etc.

An example of what I'm Thinking is inside an all electric stove and oven combo. The total current draw is typically 45 amp or so but you won't find any smaller breakers for each element nor #6 conductors to each. I'm. Sure theres a logical difference but what might that be? Probably UL.

Bobby_M said:

An example of what I'm Thinking is inside an all electric stove and oven combo. The total current draw is typically 45 amp or so but you won't find any smaller breakers for each element nor #6 conductors to each. I'm. Sure theres a logical difference but what might that be? Probably UL.

Click to expand...

Agreed Bobby. While technically you can protect every single smaller gauge wire in a device with a whole whack of fuses or breakers, you usually don't see it done to the same level that I see it done here sometimes.

Funny enough, I remember older stoves used to always have a whole row of fuses in them while new ones don't or at least they're not user accessible.

A pic of an older stove:



Kal

Bobby_M said:

I ask because i figure it is either going to be fine or a short. The short would trip the 50.

Click to expand...

Same reason I asked, but there's always the possibility of something (like a bad connection of some sort... maybe from a poorly crimped 10 gauge wire terminal) that could cause a current draw of more than 30A but less than 50A. Am I wrong about this? If not, a lot of smoke is possible...

Your stove example is a good example, but like you said it went through UL, whereas a homebrewer's crimped 10 gauge wire terminal did not.

For me it's been fine or short, as well, but what I'm wondering is if anyone on this forum has experienced anything besides fine or short? I just want to make sure I'm doing things right and not risking my life (or the life of someone reading this thread) over something like a couple little breakers.

The only way you could pull more current without shorting would be a change of resistance in the circuit. I've heard of heating elements pulling an amp or 2 of additional current as they get older and give up the ghost. That's the only example I could think of, even then it's not that big of a deal and a rarity. Other than that, a short is a short is a short .. either the circuit is solid or it shorts/grounds out and trips.

I used breakers in my build so that I could turn off certain components at the breaker for testing/troubleshooting. My control panel was built for 3 vessels and three elements, but I currently only use 2 elements and 2 vessels. So I have the third element breaker off. I also have contactors/switches, but I don't see a reason to provide power to the SSRs.

The internal breakers are not necessary as far as I'm concerned as long as you use fuses to isolate lower current devices.

jusware said:

The only way you could pull more current without shorting would be a change of resistance in the circuit. I've heard of heating elements pulling an amp or 2 of additional current as they get older and give up the ghost. That's the only example I could think of, even then it's not that big of a deal and a rarity. Other than that, a short is a short is a short .. either the circuit is solid or it shorts/grounds out and trips.

Click to expand...

The resistance in the circuit can increased through a poor/loose connection. There are many ways that this could be done. I noticed that the most likely culprit is the connection to a relay or terminal block. The screw that holds the terminal down can be loose to such a point that the ring/spade terminal is barely touching the contact on the relay or terminal block. Another example is a poorly/loosely crimped terminal, likely caused by the use of a cheap crimp tool.

Could dry-firing an element increase the resistance in the circuit?

I suppose it could. With enough heat, the barrier material could break down between the two halves of the element. This could lead to either infinite resistance or a dead short depending on luck, circumstances, environment, alignment of the moons, daily horoscopes or the state of the electrons union contract.