Relay boxes switch Neutral, not Hot

[dedvalson]

Hi,

I have been having some strange issues off and on with my system. After doing a bunch of testing I have determined that the relay boxes switch Neutral, not Hot. I went through with an outlet tester and measured the incoming power to the relay box and then the power coming out of the relay box.

When an outlet is switched off in the relay box, the outlet tester reads "Open Neutral" instead of going off like it should. This means that there is still full line voltage in each device, even when it is turned off. It means that devices like pumps and heaters and so forth are actually more likely to leak current into the water when they are turned off at the relay box than when they are turned on because when they are off, the entire electrical structure of the pump or heater will be a 110 volts in relationship to the water.

This seems like a pretty significant hardware problem. Is there any plans for a revised relay box that might fix this? I haven't opened the box up. Is this something that could be fixed with re-wiring or would a PC board change be needed?

Don

[rimai]

Relays switch on hot.

relay.jpg (21.2 KiB) Viewed 7649 times

[dedvalson]

Hi,

I can see what the schematic says but if you buy a $8 outlet tester at Home Depot you will see that it says otherwise.

At least on outlets 7 and 8, which are the ones I measured. I will measure some of the others.


Don

[dedvalson]

Hi,

I just tested outlets 1, 2, 5, and 6. (didn't test 3 and 4)

1, and 2 read the same as 7 and 8, that is the neutral is switching.

5 and 6 actually show a hot / ground reversal when they are turned off, which is probably leakage through the filters.

I have tried this with two different models of outlet tester and 2 different relay boxes now.

Don

[duck]

how are you testing?

[dedvalson]

I used a standard 3 prong outlet tester like you can buy at Home Depot or Lowes. They have 3 neon lights in them. When plugged into a properly wired outlet, two lights glow, 1 which indicates voltage between Hot and Neutral and 1 which indicates voltage between Hot and Ground. There is a 3rd light which should not come on that indicates voltage between Neutral and Ground.

I plugged the 3 prong outlet tester into the outlet that the Relay box was plugged into to verify that it was wired correctly. It was. Then I plugged the outlet tester into one of the Relay boxes outputs. When the outlet was turned on, I got the proper lights, indicating that it was wired correctly. However, when I turned the outlet off using the client software, instead of both lights turning off (which is what would happen if the hot was switched) only one of the two lights turned off, which showed an open neutral and there was still voltage between ground and hot.

To verify this further, I connected a 15 watt bulb between Ground and Hot (I had to bypass my GFI to do this). The bulb light lit whether the outlet was turned on or off, indicating that Hot was not being switched, only neutral.

Don

[rimai]

I did find the same results and digged up to check where the swap occurred.
To correct this swap, a board revision will be needed.

[stevenhman]

Is this dangerous? What steps can be taken (on the end user side) to reduce the risks?

[dedvalson]

Is this dangerous? What steps can be taken (on the end user side) to reduce the risks?

I can't speak for anyone but myself, but I think it is dangerous. As long as all of your equipment is perfectly isolated, it shouldn't be a problem. But a frayed cable or a little leakage on a pump or heater and this could become very dangerous and could kill someone who touched the water or kill animals in the water.

Of course any aquarium should have a GFI anyway and it will protect a human, but it won't protect a fish. A GFI that plugs into the wall (sort of like a plug strip) is only $25. If you don't have one, you are flirting with electrocution on any aquarium.

There is a fairly simple workaround that I implemented. I opened up the Relay box and reversed the Hot and Neutral wires right on the IEC power connector.

You can do this without opening the box by taking a 3 prong extension cord, cutting off one end, and then wiring a new end onto it, deliberately reversing the Hot and Neutral (Black and White) but making sure that the ground connects straight through. If you are going to do this you should buy a $5 outlet tester from Home Depot. When you are done, if you plug your modified extension cord into the wall and plug your tester into it, it should show a Hot / Neutral reversal.

Either of these approaches will cause all of the outlets in the box to have a hot neutral reversal, but, in my opinion, that is much safer than an open neutral with a live hot. I am not aware of any aquarium equipment that cares about a hot / neutral reversal.

Don

[stevenhman]

How difficult would you consider re-wiring the relay box? Would you mind taking a picture of what you are talking about? While the other 'fix' is tempting, I got the RA to cut down on plug craziness.

[dedvalson]

How difficult would you consider re-wiring the relay box? Would you mind taking a picture of what you are talking about? While the other 'fix' is tempting, I got the RA to cut down on plug craziness.

Hi,

The following picture shows the box BEFORE the mod. To preform the mod, just pull off the terminals marked with the blue squares, swap them and reconnect them. The hard part is getting the box open. Once you have done that it takes less than a minute.

[dedvalson]

I think this goes without saying, but I will say it anyway.

UNPLUG THE RELAY BOX BEFORE YOU TRY TO OPEN IT.

[stevenhman]

Thanks! That is definitely within my skill level. I will fix this up tonight!

[adamg]

My RA is doing same thing i got a tester and tested with outlets on and OK then turn off with controller and open neutral on some outlets and hot ground reverse on others.. A little concerned... is there a fix for this other than opening box and messing with the original setup? please let me know

[adamg]

My RA is doing same thing i got a tester and tested with outlets on and OK then turn off with controller and open neutral on some outlets and hot ground reverse on others.. A little concerned... is there a fix for this other than opening box and messing with the original setup? please let me know

[rimai]

You can send it back for repair.
PM me if interested.

[bigHUN]

Roberto, you got mail

[dlplunkett44]

Is this still an issue with the relay boxes being purchased now?

[rimai]

This has been fixed a while ago.