Replacing 10/3 low voltage transformer

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Old 09-15-17, 01:47 PM
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Replacing 10/3 low voltage transformer

Adapting 10/3 to new transformer?......

2 of our 5 low voltage transformers, used for low voltage landscape lighting, have died and needed replacement. In my rush to get them replaced, I ordered a couple nice Volt Brand 12v low voltage transformers with astronomical timers and when they arrived today, I realized I had a problem with the current wiring.

The dead transformers that are being replaced use a 10/3 12v setup that I am not familiar with and am not sure will work with the new transformers. Since our lighting setup is pretty comprehensive, I am REALLY hoping I can avoid doing new cable runs.

I have attached a picture of the terminals of the transformers being replaced. I have also attached the PDF manual for the product. In short, they are 600w 12v ac transformers but instead of the standard 2 wire terminals, it uses a 10/3 setup. I assumed one terminal was common but it looks like I am wrong.

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You can also view our current transformer at https://www.e-conolight.com/pdf/Inst...s/CI147X03.PDF

I am confident I have sized everything correctly and am happy with the transformers I bought to replace these, I am just hoping I can somehow get these new Volt transformers to work with my current 10/3 wiring setup.

I cannot even find 10/3 transformers for 12v ac on the web, so I am a bit confused why our electrician used these only 4 years ago when we had everything installed.

Is there any way to make this work?

Thank you SO much in advance!
 
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Old 09-15-17, 03:22 PM
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That transformer has two 12 volt circuits as outputs. The center terminal is common to both circuits.
 
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Old 09-15-17, 05:09 PM
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Welcome to the forums.

Your confused...... so am I. I see very little benefit to using a dual secondary transformer in low voltage lighting like this. Quite frankly..... this is the first time I have ever seen it used like this. I have only ever used 10-2 and 12-2 wiring. This method saves a little on wiring costs but certainly adds confusion to the mix.

Your new transformer appears to be at least twice as large as the old one in wattage. What you can try is to connect the two outer wires together. This is one terminal. The center wire is the other terminal.

You could actually check what is on each "circuit". Connect the center wire to one terminal. Connect one of the outer wired to the other terminal. This is one circuit. Now do the same for the other wire. You'll see some lights on one circuit and some on the others.
 
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Old 09-16-17, 10:26 AM
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First, thank you guys for the helpful information! I am relieved I am not the only one confused why our electrician went this route. This is also the first and only forum that replied with "nice and constructive" answers!

Hopefully, I can give some more details and get some more clarity on how to proceed.

The transformers being replaced are rated at 600w each. The new ones are only 300w since I migrated to LED bulbs and also removed quite a few unneeded lights. Each will only be using about 50% of their capacity. so they are sized correctly.

We had a big ol' patio and the outdoor living area built in our backyard and all of the cable runs were done then. Unfortunately, I was disabled at the time due to major back surgeries and I didn't get any diagrams when constructed for any of the landscaping or hardscapes. Hindsight is always 20/20!

The run of lights connected to the each transformer is spread out, so that is why this is so confusing. I maybe understand if all of these lights were in a row but they are not; They all over...the more I try to figure it out, the more confused I am at the decision.

Now back to the issue at hand...

I do not know if he used a single feed, dual feed or loop feed when installing this. I am guessing a dual feed because I can connect terminal 1/2 and get some lights and then power 2/3 and get the other lights. I do not get anything if I connect terminals 1/3. So the old transformer was somehow sharing a terminal between the two internal 300w transformers for a total of 600w at about 110w per circuit dependant on how it was wired (single feed, dual feed or a loop). Since we're getting power at each circuit/terminal, the center wire is not considered "common" like PCBoss said, is it?

If the center wire is truly "common", couldn't I just split that wire and run it to both terminals? So it would look like:

T=Terminal
W=Wire

OLD
T1 T2 T3
W1 W2 W3

NEW
T1 T2
W1/W2 W2/W3

Thank you again!
 
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Old 09-16-17, 11:34 AM
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If there is a single three wire cable..... then he used a dual feed. He may have run three wire cable 100' away from the transformer and then split to different directions. The three wire saves running a 4th conductor to the transformer. Technically to replace what you had you would need two 12v transformers to replace the dual one. One terminal of each transformer would be tied together and would be the new common.
 
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Old 09-16-17, 09:43 PM
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I meant it was common to both circuits . Didn't mean to confuse .
 
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Old 09-17-17, 12:13 PM
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Thank you PJ for that info! So Could I use a multiterminal transformer or do they require physical separation?

For example, can I still use this? VOLT® Clamp-Connect 300 Watt (12v/15v) Multi-Tap Low Voltage Transformer for LED Landscape Lighting | VOLT Lighting
 
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Old 09-17-17, 12:43 PM
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Those Volt transformers are all single output type transformers. They have multiple voltage taps for different length wiring systems but are still considered as one transformer.

This one from Kichler is the only dual transformer I've found. The cost is prohibitive.
Kichler-15PRD600SS-Professional-Transformer-Stainless/dp/B000H6Y5QW
 
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Old 09-18-17, 12:47 AM
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It looks like I have indeed hit a dead end then!

Looks like running some new cables might be in my future.

Thanks again
 
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Old 09-18-17, 09:41 AM
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I told you what to try back in post 3.
 
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Old 09-25-17, 10:29 AM
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Thanks, PJMax! I had already tried your suggestion prior to your comment and determined which wires were powering which lights.

I ended up doing a new wire run for one new transformer but am still debating my path forward for the other since the runs go under hardscapes.

Thanks again!
 
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