Stainless Electric Boilers and Earthing

[donnchadhc]

Thoughts? Is it required or will the earth in the element suffice? Assuming the circuit is RCD protected of course.

[brenmurph]

cant go wrong with extra earths. . If u put an element onto a boiler / pot, it might be worth adding an earth on to the casing,
maybe a NHC Lecky can comment?

[Damien M]

There's alot  on here about that!

But the basic rule of Anything metal around electricity must be earthed applies. The earth of the Element going to ground is not enough, the Metal components ( tank, keg) must also be earthed too! 

[brenmurph]

and ss. sinks and copper pipework

gotta make it easy for the flow to go to earth rather than via u to earth.

re RCD, they are great but its not a given that it will work ( all electronics can fail), the time of tripping is dependant on a lot of physicsy stuff including length of cable and thickness of cable from rcd device and so on.

Wire ur gear as if theres no RCD in circuit and make every metal componant connected to a good earth. Ive even an 1 metre earth rod in my brewery to be sure

If theres a lecky near u ask how much he / she charge to have a look at ur setup. May be only 20 euros for advice and a safety check

[donnchadhc]

Those are my thoughts exactly. I just see lots of stainless kettles on-line with little or no earthing, didn't look right to me!

Read the Earthing Electrical Elements  post, but have a few more questions if possible.

Would you run a fairly thick cable from the earthing pin and weld it to the frame (Would one point beside the terminal suffice)? What would you use to welding, a high temp glue? Is there any way to run the earthing wire in a conduit/cover to make it a neat job, less chance of snagging it during a brew day?

[donnchadhc]

Actually, there's a nice neat example on the electric brewery site.

Is one attachment sufficient does anyone know?

Thanks for the replies.

[JD]

Just be aware that that example is a US setup. They have a different set of rules and standards that apply, particularly around the area of safety and earthing. It's not that theirs is any less safe, but it is different.  Their 240VAC supply is phase and anti-phase whereas ours is phase and ground. Their 110VAC is phase (or anti-phase) and ground. We only get 110VAc using a transformer. All this means that the rules around ELCBs RCDs, earthing, etc. are different on opposite sides of the big pond.

[brenmurph]

On this point...ive asked before...is there an electrician in the club...Im sure he could be useful and make a few bob as well?

[donnchadhc]

Just be aware that that example is a US setup. They have a different set of rules and standards that apply, particularly around the area of safety and earthing. It's not that theirs is any less safe, but it is different.  Their 240VAC supply is phase and anti-phase whereas ours is phase and ground. Their 110VAC is phase (or anti-phase) and ground. We only get 110VAc using a transformer. All this means that the rules around ELCBs RCDs, earthing, etc. are different on opposite sides of the big pond.

Understood, sort of a roundabout way to get 240V when there is only 110V available? I'm just trying to get right in my mind a nice neat detail that earths the pot and minimises the chances of the cables catching. I'm not 100% sure on this detail either as he has it earthed to the box but not directly to the pot (if you know what I mean), I feel the rubber washer could get in the way.

So if they were a half phase of out step the PD would be constant, and therefore it would be DC?

Not the way I understand it. One Live is at +110V AC and the second live is at -110V AC. When they are at their maxima the difference is 240V, at their minima 0V, they alternate at the same rate, hence still AC? Does this affect the frequency at all?

And just to go OT for a sec, is our Live not 350V with the Neutral 110V? Does that mean the US neutral is actually 0V?

[JD]

So if they were a half phase of out step the PD would be constant, and therefore it would be DC?

Not the way I understand it. One Live is at +110V AC and the second live is at -110V AC. When they are at their maxima the difference is 240V, at their minima 0V, they alternate at the same rate, hence still AC? Does this affect the frequency at all?

What Donnchadhc said. Think of a centre tapped transformer. You have +110, 0, -110 on the outputs.

And just to go OT for a sec, is our Live not 350V with the Neutral 110V? Does that mean the US neutral is actually 0V?

Yes-ish and no. It all begins as three phase at the substation where a Y connected three phase transformer combines the three phases into a notional neutral. This neutral is connected to the ground (literally a spike is shoved into the ground). This ground connection is always at 0V. The three phases are then distributed to all and sundry and individual phases are fed to various premises. As long as the loads on each phase are in balance, each phase relative to the ground has a 220V RMS value. Relative to each other they have a 380V RMS value.

When the transformer on the pole nearest your house provides power it does so using a single wire to provide the live and a ground connection to provide the neutral (this spike into the earth thing again). The meter box has an earth connection that provides a local neutral. A separate earth connection is used as a safety feature (the green and yellow wire) that is distributed to all appliances, sockets and fittings.  The reason for this separate earth is because the local neutral is not a reliable 0V when a heavy load is drawing power. The separate earth provides a low impedance connection to the ground to ensure that no appreciable voltages are present on grounded equipment.

/J