Aussiedistiller, Home Distilling, Moonshine, Home Brew

Here's a couple of photos of my recent build. It's only controlling a 2000W boiler, hence why I'm able to use 10A rocker mechs. It's based on Punchy 21's original wiring.
Had most of the bits laying around so only cost me about $30, gotta be happy with that :handgestures-thumbupleft:

Cheers,
Hooky

Super neat job, well done.

No earth to the pot body?
Might be a good idea.

scythe wrote:No earth to the pot body?
Might be a good idea.

And the door on the cabinet. There's eve a stud there ready for it.

Cheers,
Prof. Green.

It's a steel powder-coated box, not plastic. When the door is closed it is solidly earthed at 3 separate points. The box has an internal RCD/MCB. The shed also has RCD/MCB protection
The pot is electrically-isolated from mains power in these SCR type relays, it only signals SSR what its output should be (imagine an automotive driving light relay, high beam sends 12V to the relay coil, relay energises & turns on. This sends a separate high-power 12V supply to the lights).

Cheers;

Hooky

I too have a powder coated steel industrial style enclosure.
Does not mean i will trust the powder coating to act as a conductor to allow the earth "circuit" to complete.

And what does it cost you to put some extra bits of wire in there?

Hooky wrote:It's a steel powder-coated box, not plastic. When the door is closed it is solidly earthed at 3 separate points. The box has an internal RCD/MCB. The shed also has RCD/MCB protection
The pot is electrically-isolated from mains power in these SCR type relays, it only signals SSR what its output should be (imagine an automotive driving light relay, high beam sends 12V to the relay coil, relay energises & turns on. This sends a separate high-power 12V supply to the lights).

Cheers;

Hooky

OK mate, it's your life but I would not trust the hinges and lock mechanism to earth that panel. That is why there is an earth stud on it. Have you had this checked by a qualified sparky?


Cheers,
Prof. Green.

Sorry for not answering earlier, not online much while away at work.

OK, first things first.

Yes, I shouldn't have posted photo's before earthing the door (the box itself doesn't have an earth stud so a bit more playing around). This will be done before being used in anger .

Second, I am a Sparky so what I'm saying next is based on technical knowledge.

An RCD is also known as core-balance earth leakage. Not suggesting I would ever do so but I COULD cut the main earth wire & the RCD would still trip (within about 20 mS) in the event of the current flowing in the active & neutral being out-of-balance by 30mA (earth fault).

I have seen mentioned in a number of different posts about earthing the pot. Absolutely not necessary. The SSR's are connected in the neutral, therefore there is NO voltage present at the SSR terminals, it has already been 'dropped' across the load (boiler element). Only current is present in the neutral. The pot only controls the output of the SSR, there is no connection to the boiler connection. The pot should have a plastic knob fitted always.

Bottom line, if there was ever any mains voltage on the pot it would disintegrate with a very loud bang, they are not designed for that.

Again, I apologise for rushing to post the initial images, my bad.

Cheers,

Hooky

scythe wrote:I too have a powder coated steel industrial style enclosure.
Does not mean i will trust the powder coating to act as a conductor to allow the earth "circuit" to complete.

And what does it cost you to put some extra bits of wire in there?

Powder-coating is an insulator, need to remove a little around the perimeter of holes to get a good earth :handgestures-thumbupleft:
Then test from the main earth to the item in question with a good multimeter.

Cheers,

Hooky

Thats cool not looking to get into a contest about it.

My point about the powder coating is exactly what your reply was.
I didn't trust an insulating substance to act like a conductor in the event that somehow your box became live without tripping your rcd.

Genuine question not sarcastic:
So are you saying that there is no way that voltage or current at dangerous levels could get to you through the pot?

We are all here to learn.

Hooky wrote:Yes, I shouldn't have posted photo's before earthing the door (the box itself doesn't have an earth stud so a bit more playing around). This will be done before being used in anger .

All good mate, we just need to push the safety aspect since this is an open forum and we don't need folks getting the wrong idea.

It's a great looking controller BTW. :handgestures-thumbupleft:

Cheers,
Prof. Green.

An SSR could melt into a puddle and feed 240 to the pot? - worst case scenario, would the plastic knob cover that? Also very not sarcastic :)

Hooky wrote:An RCD is also known as core-balance earth leakage. Not suggesting I would ever do so but I COULD cut the main earth wire & the RCD would still trip (within about 20 mS) in the event of the current flowing in the active & neutral being out-of-balance by 30mA (earth fault).

An RCD is a Residual Current Device also known to most people as a Safety Switch and sometimes called an earth leakage circuit breaker. They were referred to as a RCD rather than a current earth leakage circuit breaker when introduced decades ago to prevent a backlash from Electricity Customers who, in the past, had voltage earth leakage circuit breakers installed and had experienced regular nuisance tripping problems with these devices.

RCD's being an earth leakage device require a connection to Earth to operate and it is this imbalance between the Active and Neutral wires leaking to Earth that will make a RCD trip.

If you cut the main earth wire then any imbalance between the active and neutral will be flowing in the active and neutral. It will not provide a residual current to earth and will not trip a RCD...
And an inbalance current between active and neutral is something any sparky should be able to plot with a vector diagram ;-)

scythe wrote:Thats cool not looking to get into a contest about it.

My point about the powder coating is exactly what your reply was.
I didn't trust an insulating substance to act like a conductor in the event that somehow your box became live without tripping your rcd.

Genuine question not sarcastic:
So are you saying that there is no way that voltage or current at dangerous levels could get to you through the pot?

We are all here to learn.

Current is the killer! 30mA is the level at which it affects the human body, causing the heart to go into arythmia (especially if you receive a shock from one hand, across the chest & exiting through the opposite hand). This is why most RCD's are 30mA units. Hospitals have 10mA units.

An RCD senses out-of-balance current so if the current flowing in the active & neutral is not the same (by 30mA or more) the RCD trips. We can assume if it is out-of-balance then it is flowing to earth somewhere. If your RCD is installed correctly your box will NEVER become live, it's just not possible.

I am lucky in that I have RCD's in my home as well as having fitted one in the box (if you have them it's a good idea to give them a function test monthly or better still, an injection test 3 monthly if you have a Sparky mate with the correct tester :handgestures-thumbupleft: )

Cheers,

Hooky

Professor Green wrote:

Hooky wrote:Yes, I shouldn't have posted photo's before earthing the door (the box itself doesn't have an earth stud so a bit more playing around). This will be done before being used in anger .

All good mate, we just need to push the safety aspect since this is an open forum and we don't need folks getting the wrong idea.

It's a great looking controller BTW. :handgestures-thumbupleft:

Cheers,
Prof. Green.

Thats fine, could be neater but...

Cheers,

Hooky

RC Al wrote:An SSR could melt into a puddle and feed 240 to the pot? - worst case scenario, would the plastic knob cover that? Also very not sarcastic :)

A properly installed RCD would prevent that. The SSR is solidly earthed to the base plate via the heatsink. If it develops an earth fault, RCD trips & removes power from the box. It won't allow a reset until the fault is removed &/or rectified.

In an ideal world all boxes l8ke this would have either internal or external RCD protection.

Cheers,

Hooky

Buzz wrote:

Hooky wrote:An RCD is also known as core-balance earth leakage. Not suggesting I would ever do so but I COULD cut the main earth wire & the RCD would still trip (within about 20 mS) in the event of the current flowing in the active & neutral being out-of-balance by 30mA (earth fault).

An RCD is a Residual Current Device also known to most people as a Safety Switch and sometimes called an earth leakage circuit breaker. They were referred to as a RCD rather than a current earth leakage circuit breaker when introduced decades ago to prevent a backlash from Electricity Customers who, in the past, had voltage earth leakage circuit breakers installed and had experienced regular nuisance tripping problems with these devices.

RCD's being an earth leakage device require a connection to Earth to operate and it is this imbalance between the Active and Neutral wires leaking to Earth that will make a RCD trip.

If you cut the main earth wire then any imbalance between the active and neutral will be flowing in the active and neutral. It will not provide a residual current to earth and will not trip a RCD...
And an inbalance current between active and neutral is something any sparky should be able to plot with a vector diagram ;-)

Hi Buzz, didn't see your reply until I started the above replies. I was going to mention 'Safety Switches'.

Where I mentioned that I could cut the main earth wire & still get an RCD trip, it was probably not a comment for a forum such as this :violence-stickwhack: as it would not trip until the circuit to earth was completed & we both know that would be through contact to the box. Someone would still receive a low-level shock before the RCD tripped.

Note to self: Be far more careful when trying to make a point.

Bloody hell, vector diagrams, there's something I haven't played with in a long time :shock:

Cheers,

Hooky