3 phase single phase. help needed crossy

[carlyai]

Spot on again.

I'll get this cement sorted (sorry, I'll get it as close to sorted as I can), get the gutter on the shed, and crank it up tomorrow. I'll put the AVR's between the mains incoming breaker and the transfer switch.

Thanks again.

[RichCor]

[...]

So inputs to the SC are causing it to trip.

The SC is a Safe-T-Cut Gold Special 3 phase model PR40-63A

I just wonder if this model has some other special features other than tripping from the RCD as it does mention RCD protection, Short protection and overload protection. May be they all do.

Thought it might be helpful to post the cover of your Safe-T-Cut PR-40-63A

Where do you have the "Sensitivity" switch set?

[carlyai]

[...]

So inputs to the SC are causing it to trip.

The SC is a Safe-T-Cut Gold Special 3 phase model PR40-63A

I just wonder if this model has some other special features other than tripping from the RCD as it does mention RCD protection, Short protection and overload protection. May be they all do.

Thought it might be helpful to post the cover of your Safe-T-Cut PR-40-63A

Where do you have the "Sensitivity" switch set?

Mine is a nicer colour that yours.

Did have the current set at 20 ma but when we did the singlle phase AVR testing connected to the output of the Safe-T-Cut connected to the CU, the SC tripped.

When I reset the curent to 30 ma the SC didn't trip with the AVR's on load, but would not reset after a manual trip.

So the current is set at 30 ma.

Pic 1: Is how we wired the SC

Pic 2: Alternate wiring

Pic 3: Dot point 1 mentions about the rcd time to operate at 0.4 ms so think this dot point 1 is about the rcd protection.

Pic 4: Dot point 3 mentions short circuit protection.

Pic 5: Dot point 4 mentions overload protection

Pic 6: Pix of SC

Pic 7: Pix of SC

Pic 8: Pic of box

Pic 9: Box

Pic 10: Box

[Crossy]

If you have any N-E connections (as shown on the instructions) it is imperative that these are all upstream (before) the Safe-T-Cut, otherwise you will get random tripping.

[RichCor]

If you have any N-E connections (as shown on the instructions) it is imperative that these are all upstream (before) the Safe-T-Cut, otherwise you will get random tripping.

I was just about to ask about that.

Safe-T-Cut online manual .pdf

Page 7 shows an example for a direct-output to presumably a single load, where N-E are bonded together before the Safe-T-Cut.

Page 8 shows an example connected to a Consumer Unit where N-E are bonded in the CU, and N is fed back into the input of the Safe-T-Cut and and the output back into the main breaker of the CU.

...so my question to Crossy is, how would you recommend the Safe-T-Cut N be run on Carlyai's board given that the N-E is upstream (prior to the Transfer Switch, if I recall correctly)?

Edit: OH, and Carlyai, Is there a separate EARTH Bar in your CU. From what I see in the pic, there's only a NEUTRAL Bar. Where to the Grounds go?

Edited May 7, 2015 by RichCor

[Crossy]

Both arrangements are electrically identical.

I would do it like Page 5 (page 7of the .pdf). Once the N-E link is in place the TN-C supply becomes TNC-S with MEN, from this point onwards the ground wire must remain separate from the Neutral.

Note that the second example (link in the CU) does NOT have any N-E connection inside the CU.

EDIT We need a better photo of the area of those N / E bars. I suspect our sparks has just hooked everything together in there, would explain the interesting tripping.

The Neutral going TO the Safe-T-Cut is linked to the ground, the Neutral coming FROM the Safe-T-Cut must remain separate from the ground connections.

[bankruatsteve]

So, are the AVR's downstream from the RCD? If so, would it not be better to place them upstream? Then, whatever is done with N shouldn't be a problem. ?

[Crossy]

So, are the AVR's downstream from the RCD? If so, would it not be better to place them upstream? Then, whatever is done with N shouldn't be a problem. ?

I think the latest incarnation will have the AVRs right at the supply inlet, before the transfer switch and the Safe-T-Cut. I suspect this will be the best place for them in case there are any odd imbalances whilst they adjust to supply variations.

I've spoken to them-as-knows about 3-phase RCDs and missing / low phases, they agree that there should be no issues. It's more likely poor N-E insulation (short) downstream from the Safe-T-Cut causing the random tripping although transient noise (from lightning) is also a possibility.

By the way, your MOVs should go right at the front too, put them with the AVRs to stop transients getting into the protected wiring.

[carlyai]

Both arrangements are electrically identical.

I would do it like Page 5 (page 7of the .pdf). Once the N-E link is in place the TN-C supply becomes TNC-S with MEN, from this point onwards the ground wire must remain separate from the Neutral.

Note that the second example (link in the CU) does NOT have any N-E connection inside the CU.

EDIT We need a better photo of the area of those N / E bars. I suspect our sparks has just hooked everything together in there, would explain the interesting tripping.

The Neutral going TO the Safe-T-Cut is linked to the ground, the Neutral coming FROM the Safe-T-Cut must remain separate from the ground connections.

Here are pix of CU with cover removed.

The earth bus is on the rhs.

If I would have wired it, all the black wires would have been neutral wires and all the green wires earth wires. Hopefully the sparky did tne same.

There are no green wires terminating on the neutral bus and there are not black wires terminating on the ground bus.

Here are the pix.

In the last pix you can see the green wire with black tape around the end, this is the link we removed between neutral and earth bars.

[carlyai]

Crossy,

What computer application do you use to draw up your wiring schematics?

[carlyai]

So, are the AVR's downstream from the RCD? If so, would it not be better to place them upstream? Then, whatever is done with N shouldn't be a problem. ?

I think the latest incarnation will have the AVRs right at the supply inlet, before the transfer switch and the Safe-T-Cut. I suspect this will be the best place for them in case there are any odd imbalances whilst they adjust to supply variations.

I've spoken to them-as-knows about 3-phase RCDs and missing / low phases, they agree that there should be no issues. It's more likely poor N-E insulation (short) downstream from the Safe-T-Cut causing the random tripping although transient noise (from lightning) is also a possibility.

By the way, your MOVs should go right at the front too, put them with the AVRs to stop transients getting into the protected wiring.

This morning the lights were dimming, fans really slow, but no safe t cut trip.

No storms or lightning in the area.

I ordered 3 DIL (is that dual in line as in electronic packages?), MOV's to go in the CU. But I'll have to install them in the first mains power entry box with the mains cct breaker in it to be right at the front of everything.

Should I try and cancel the order and order a 3 phase MOV or can you buy small DIL box to mount the 3 MOV's in?

[carlyai]

I think the wiring is wrong.

I can't see an earth coming back from the CU to the earth outside, but, before the tiler tried to lay the tiles, I did notice 3 earth leads coming from inside the house going to 3 earth spikes outside the house.

I asked him 'are they for the 3 phases?' and he said 'yes'.

Didn't give it another thought at the time, but now not too sure what that meant. Why have 3 earths to 3 spikes?

Will have to trace out the wires, but the neutral (supposedly) from the input to the SC terminates on the neutral in the CU but doesn't go to ground as far as I can see.

At least my confidence is coming back and I may one day be able to ditch the flip-flops and marigolds (I presume they are gloves?)

[Crossy]

Small DIN boxes are readily available (try your local electrical emporium, but I got several from HomePro) or just mount a bit of DIN rail in a regular plastic box.

Yes, "marigolds" is UK English for rubber gloves.

You really need to sort out your earthing, it could be the reason you have RCD tripping.

[carlyai]

Small DIN boxes are readily available (try your local electrical emporium, but I got several from HomePro) or just mount a bit of DIN rail in a regular plastic box.

Yes, "marigolds" is UK English for rubber gloves.

You really need to sort out your earthing, it could be the reason you have RCD tripping.

Was on the balcony watching sand unloaded during a storm, saw the flash, heard the SafeTCut 'Clack', then heard the thunder noise. All within a asecond or so.

Just starting to trace out some wires.

Probably need to buy some gold for Mother's Day as I think the helper has quit. I always let her test the actives first.

[Crossy]

This thread (which I started specifically to address the RCD issue) is worth a look http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=61666&enterthread=y

You don't need to be a member to read.

[Crossy]

Crossy,

What computer application do you use to draw up your wiring schematics?

Mostly I use TinyCAD http://sourceforge.net/projects/tinycad/ free I've added a few of my own library elements.

I use FreePCB to do PCB layouts.

[carlyai]

This thread (which I started specifically to address the RCD issue) is worth a look http://www.theiet.org/forums/forum/messageview.cfm?catid=205&threadid=61666&enterthread=y

You don't need to be a member to read.

[carlyai]

Crossy

Thanks again

Firing up my big computer so I can print this stuff out and ponder.

The mob u get advice from seem very knowlegable.

I'm enjoying this

[RichCor]

carlyai, are you keeping tracking each time the Safe-T-Cut trips (Data, Time, Major Appliance running, major external event)?

Are you still getting trips, or has it been quiet since the last storm?

Have you traced back the origins of the three Ground Spikes?

[carlyai]

carlyai, are you keeping tracking each time the Safe-T-Cut trips (Data, Time, Major Appliance running, major external event)?

Are you still getting trips, or has it been quiet since the last storm?

Have you traced back the origins of the three Ground Spikes?

Good advice, but I haven't got around to keeping track yet, but, the SC doesn't randomly trip, it trips when there is lightning around.

I have enclosed a pix of those 3 earth wires coming from the inside of the house and to 3 earth spikes.

I hope the earths go back to the earth bus on the CU. Where else would they go? But now I'm wondering 'why 3 earth wires and 3 ground spikes?

Can't get to them now as the tiler tiled over them while I was away.

I don't think they can be the earths for the hot water system as we only have 2 multi point units and the wires from them come back to 2 X 3 pole breakers in the CU.

I will make some leadsi up and do some wire traceing.

I think I've found a problem, think that is , have to do some more panel removing and tracing, the neutral from the mains into the SafeTCut seems to be floating, it doesn't seem to be wired to any earth near the CU as per the SC diagram.

This means that the closest earth spike, NE is about 20 m away thru underground cable upsteam of the SC.

During a lightning strike could the voltage of this 20 m neutral float above ground PD and cause the inbalance and

trip?

[carlyai]

carlyai, are you keeping tracking each time the Safe-T-Cut trips (Data, Time, Major Appliance running, major external event)?

Are you still getting trips, or has it been quiet since the last storm?

Have you traced back the origins of the three Ground Spikes?

Good advice, but I haven't got around to keeping track yet, but, the SC doesn't randomly trip, it trips when there is lightning around.

I have enclosed a pix of those 3 earth wires coming from the inside of the house and to 3 earth spikes.

I hope the earths go back to the earth bus on the CU. Where else would they go? But now I'm wondering 'why 3 earth wires and 3 ground spikes?

Can't get to them now as the tiler tiled over them while I was away.

I don't think they can be the earths for the hot water system as we only have 2 multi point units and the wires from them come back to 2 X 3 pole breakers in the CU.

I will make some leadsi up and do some wire traceing.

I think I've found a problem, think that is , have to do some more panel removing and tracing, the neutral from the mains into the SafeTCut seems to be floating, it doesn't seem to be wired to any earth near the CU as per the SC diagram.

This means that the closest earth spike, NE is about 20 m away thru underground cable upsteam of the SC.

During a lightning strike could the voltage of this 20 m neutral float above ground PD and cause the inbalance and

trip?

PowerRunToHouse.jpg

Think I've worked out the 3 earths.

One to the Cu.

And two to the 2 multi point hot water systems.

That would make sense. Still ........

[Crossy]

Careful.

Any N-E link MUST be on the supply side of the Safe-T-Cut or you'll get tripping.

All the grounds should be connected together.

Why not draw out what you think you have and check off each wire as you verify? You'll have a handy as-built drawing afterwards too.

[RichCor]

Tracing from the Safe-T-Cut, back upstream, how many N-E bonds are there, where are they located (ie: Generator, Transfer Switch, AVR, Water Pumps, upstream Mains Breaker) and where are the Earth Ground spikes for these located and what distance in relation to the THREE tied Earth Ground spikes for the CU and Heaters?

I have a feeling there's no wire-tied Earth grid in place.

Are the Three Tiled-Over Earth Ground Spikes in 'damp' soil, and how does the tile affect this.

[carlyai]

Testing Testing

I checked out as much of the wiring as I could. I didn't want to take the tiles up that are now covering the 3 green earths going to 3 earth rods.

I checked around with my meter for wiring connections and wired the SafeTCut as per page 5 of the pdf diagram. Just test leads connected at the present.

It's been 2 days now without a SC trip but no big storms around, although this morning we did lose power and had some power flicks, rapidly off then on then off then on again.

The SC made some big end bearing noises (like my Sunbeam Alpine use to do), but did not trip. I manually tested the SC and it did trip.

I have enclosed some pix.

The first 2 are of the outside connection of the tiled over earth cables and the transfer switch and underground bcable from the fence and cable entry to the house.

The other pix are of the SC and CU temp testing wiring.

The last pix is of the link that was removed from the Neutral to Earth bus.

[Forkinhades]

......Blimey

Thats about as polite as I can be

[carlyai]

Blimey I understand

But I don't understand the rest

Please be unpolite

[RichCor]

I checked out as much of the wiring as I could. I didn't want to take the tiles up that are now covering the 3 green earths going to 3 earth rods.

I checked around with my meter for wiring connections and wired the SafeTCut as per page 5 of the pdf diagram. Just test leads connected at the present.

It's been 2 days now without a SC trip but no big storms around, although this morning we did lose power and had some power flicks, rapidly off then on then off then on again.

Can you describe your Earth Ground system

how many Earth Ground stakes are in play on your property,

where are they located

are the Earth Ground directly tied/wired together in a direct grid, or if not

what distances are they from each other.

how many N-E ties are in play

where are they located

[carlyai]

I checked out as much of the wiring as I could. I didn't want to take the tiles up that are now covering the 3 green earths going to 3 earth rods.

I checked around with my meter for wiring connections and wired the SafeTCut as per page 5 of the pdf diagram. Just test leads connected at the present.

It's been 2 days now without a SC trip but no big storms around, although this morning we did lose power and had some power flicks, rapidly off then on then off then on again.

Can you describe your Earth Ground system

how many Earth Ground stakes are in play on your property,

where are they located

are the Earth Ground directly tied/wired together in a direct grid, or if not

what distances are they from each other.

how many N-E ties are in play

where are they located

[carlyai]

The 3 phase comes overhead and by conduit from the lane about 30 m.

It terminates in a metal box with neutral tied to earth and earth rod.

Underground for another 15 m (4 wires) to transfer switch.

From the transfer switch outside through the cavity to the consumer unit about 5 m.

I PRESUME the earth from the consumer unit goes to the earth rods under the transfer switch.

This is what I have been told.

I have not taken the tiles up covering the earths to measure the resistance from the consumer unit to the earths.

So in all I have 6 earth rods that I am aware of.

1 15 m from the house on the main 3 phase in.

3 all within half a metre of each other under the transfer switch.

3 on the air conditioners one on each air conditioner as the aircon guy insisted I must have earth rods with the new inverter type aircons .

I have 2 neutral earth connections.

One on the mains coming in and one at the safe t cut.

[RichCor]

No additional Earth Ground rods on the Water Pumps?