scythe wrote:No earth to the pot body?
Might be a good idea.
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
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?
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 .
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).
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.
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.
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 :)
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 ;-)
Users browsing this forum: No registered users and 29 guests