Quick question about fast blow fuse holders

[Bnewman]

I am looking at a 120 v 20amp system. PJ's diagram calls for several fast blow fuses to protect the PID, Pump, and Estop. Let me just say, like most of the people reading this forum, I am a novice at this. So, thank you for all you have posted here.

1. PJ's diagram for a single 2000w element 1 pid and 1 pump shows fast blow fuses in place in line with 120v I am assuming a 15-20amp. Why dose this load not blow the fuse every time?

2. I would assume that a controller build for a 20amp system should use at least a 12 gauge wire. But i keep finding 22 AWG inline fuse holders. I need at least a 12 gauge /AWG fuse holder, don't I?

3. And one more for good the heck of it. PJ's diagram calls for a 1k ohm 1 watt resistors in front of the E-stop with a fast flow 1 am fuse. I looked these up on line and I am very confused as to how I am going to wire them up?

Once again I am very new to all of this and would greatly appreciate any help you can give.

Thanks,

Bryan

 

[doug293cz]

Can you link to the P-J drawing you are talking about. That will make it easier for us to understand just what you are asking.

Brew on

 

[Bnewman]

https://www.homebrewtalk.com/showthread.php?t=382286

120v 1pid 1 pump

 

[raouliii]

Assuming you are referencing your question to the following diagram: The above link, Post #2, ninth diagram down, Labelled "120v 2000 Single Element Single Pump Single PID EStop"

The bottom left, 4amp fuse protects only the pump. Only the current drawn by the pump flows through it.
The bottom right, 1amp fuse protects only the PID. Only the current drawn by the PID flows through it.
The upper left, 1amp fuse is associated with the Estop only. It only has current drawn through it when the estop is actuated. When actuated, the estop will only draw about 60milliamps because of the 2k of resistance. The 60milliamps to ground is well above the ground fault trip current of a functioning GFCI breaker or receptacle.

The circuit has no fuse that carries the current of the element. Protecting the element and its wiring is the responsibility of the GFCI circuit breaker mentioned near the top left of the diagram.

 

[Bnewman]

That was very helpful! So can I use an inline fuse holder that is 22 AwG since the pump/pid/e-stop will each be drawing a low ampage?

 

[RufusBrewer]

Have you ever looked at a fuse, seen the skinny wire inside it and ask yourself, "When do I connect 2 pieces of 12 gauge wire with this paper clip in a glass tube?"

For a short run, you do not need a fuse made of 12 gauge material.

 

[doug293cz]

I am looking at a 120 v 20amp system. PJ's diagram calls for several fast blow fuses to protect the PID, Pump, and Estop. Let me just say, like most of the people reading this forum, I am a novice at this. So, thank you for all you have posted here.

1. PJ's diagram for a single 2000w element 1 pid and 1 pump shows fast blow fuses in place in line with 120v I am assuming a 15-20amp. Why dose this load not blow the fuse every time?

2. I would assume that a controller build for a 20amp system should use at least a 12 gauge wire. But i keep finding 22 AWG inline fuse holders. I need at least a 12 gauge /AWG fuse holder, don't I?

3. And one more for good the heck of it. PJ's diagram calls for a 1k ohm 1 watt resistors in front of the E-stop with a fast flow 1 am fuse. I looked these up on line and I am very confused as to how I am going to wire them up?

Once again I am very new to all of this and would greatly appreciate any help you can give.

Thanks,

Bryan

1. The current flowing in the circuit branches with the fuses is low to very low. The PID power consumption is less than 5W according to Auber, so the max current would be (from Power = Current * Voltage) 5 / 120 = 0.0417 A. This current would never blow a 1 A fuse. A typical Chugger pump is rated as drawing 1.4 A, and motors usually draw a higher surge current when turned on, so a 10 A fuse is specified to handle any surge current. The only circuit branch that would carry 23 A is the one that goes thru the contactor, SSR and heating element. That branch is not fused in the design, but rather depends on the circuit breaker in the building's service panel for over current protection.

2. A 22 AWG fuse holder is sufficient for the EPO circuit fuse and the PID power fuse as these are very low current circuit branches. I wouldn't use an in-line fuse holder for the pump circuit branch, but rather something like this: http://www.amazon.com/Screw-Panel-Mounted-Holder-Black/dp/B00AQWXW9S/?ie=UTF8&qid=1433447946&sr=8-1&keywords=panel+fuse+holder. These panel mount fuse holders can also be used instead of in-line fuse holders for the EPO and PID branches (with the specified fuse ratings.)

3. The resistors can either be connected to terminal strips, or the leads twisted together and soldered, and then the resistors, and all exposed metal, can be insulated and protected with shrink tubing.

Brew on