Where to fuse?

[dunbruha]

Hi,
I am almost finished building my electric kettle control panel, and I can’t figure out where (or if) I should put a fuse. I am attaching a diagram of my panel. Several posts on this forum suggest putting fuses in various places, but I can’t decide which is correct. I emailed Auber, and they said:

“For the controller, 250Vac > 0.1 A fast blow fuse could work but probably not necessary. There is a large resistor in the power input module that works like a fuse. The controller normally will only draw small current. If it draws more current than it should, it means something inside has been burnt. In that case, the fuse can not protect the controller. And the issue won't be fix by replacing the fuse. However, if there is a current spike come from outside the controller, then the fuse can protect the controller. But in that situation, the fuse can be placed in close to the power input in your system and so you will need a fuse with higher current rating.”

So, any advice on what kind of fuse to use, and where to put it?

 

[DU99]

i would put one just before the element.

 

[dunbruha]

i would put one just before the element.

Do you mean between the SSR and the outlet for the element? How big of a fuse?

 

[DU99]

Yes near the element.I=Watts over Volts
so watts is 2000 and volts 120= 17amps....you could use a circuit breaker

 

[dunbruha]

Yes near the element.I=Watts over Volts
so watts is 2000 and volts 120= 17amps....you could use a circuit breaker

But I already have a 20A circuit breaker for the entire circuit. My question is do I need an additional fuse somewhere else.

 

[DU99]

reasoning is if the element shorts out your won't lose the pid/ssr..see what other's think.

 

[ChocolateMaltyBalls]

I didn't fuse my PIDs for my eHERMS and things have been fine, but for my 120V eBIAB I'm planning on fuse protecting the PID with a 0.75 A fast blow. We'll see what happens and if I ever need it.

 

[whoaru99]

Well, OCP is about protecting the circuit/wiring from overload/fault, not so much the connected equipment. So, in this case, the fuse for the PID should be the demarcation point between the 20A/12ga wiring and the 18ga wiring. I'd think wire capable of handling the 20A should feed the fuse, then the appropriately-sized smaller fuse will protect the smaller downstream wiring.

 

[ChocolateMaltyBalls]

Well, OCP is about protecting the circuit/wiring from overload/fault, not so much the connected equipment. So, in this case, the fuse for the PID should be the demarcation point between the 20A/12ga wiring and the 18ga wiring. I'd think wire capable of handling the 20A should feed the fuse, then the appropriately-sized smaller fuse will protect the smaller downstream wiring.

That's a good point. I power my PIDs in the HERMS from a bus that is fused protected, and pretty much protects all of my 120V stuff. It sounds like the OP is trying to protect those expensive PIDs. I still don't really have an answer I guess, I want to protect against surges but then it doesn't take much to fry a PID so not sure I'm gonna do much with a 0.75A fuse.

 

[augiedoggy]

I used a .5a fuse to protect my 18 guage wiring powering all three of my pids as well as my timer....
Some install a breaker of fuse for the element power just in case some sort of freak failure causes the element to draw more amps than it should but less that the main panel breaker is rated for....I find the chances of this being so unlikely I skipped this fuse/breaker myself.... Besides I use a digital amp meter built in so I would actually notice if something was up...

 

[dunbruha]

So it seems I should put a fuse in the 18 gauge wire. Does this seem right?