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View Full Version : when do you move up a size in transformers?


David Gretzmier
07-08-2010, 10:21 PM
I have always had a rule of thumb on sizing transformers for bids that is in the 65% range. once i exceed 65% load on my bulb wattage count, I go up to the next size. this gives me some wiggle room to add fixtures as the customer wishes, maybe bump up wattage if I need to, go to higher taps, etc. this has always worked for me and i rarely had to replace an installed trans with a larger unit unless it involved a large upgrade later.

this year, tho, since letting folks know a per fixture price, I have been exceeding 80% all over the place and had to replace transformers that have been just installed as folks have added on way more fixtures than they used to. So I am starting to change my philosophy and going closer to the 50% threshold. but it still seems silly for me to install a 600 watt trans for a 180 watt load.

what numbers do you guys go by ?

emby
07-09-2010, 09:34 AM
Hi David,

I am pretty new and some of the more experienced here will add to this I am sure but this is what I have been doing on every job so far:
If you rule out LED's totally, I have always left myself with an extra 300 watts when installing halogens.
There have been many times where I have been asked to come back and add fixtures and I have been super happy to know that there was lots of room for the additions. The original cost of the larger transformer is minimal and it has been really nice not having to replace two year old transformers because of additions.
This has provided me and my customers lower associated costs for their wanted additional fixtures. It still is a pain sometimes as I still have to perform voltage testing on every fixture after the upgrade but I think it would be more costly and timely if you had to replace the transformer all together.

I have not installed a 100% LED system as of today but I would be interested to hear from others on their percentages for future additions.

Ken

David Gretzmier
07-10-2010, 12:26 AM
yeah, I had a feeling that this thread could turn into LED in a hurry. but seriously, folks, for those of us who use proven technology, what are your step points to the next trans? having 300 watts of wiggle room does make sense up to a 750 watt load. even though you may appear to have 450 watts of wiggle room on a 1200, really at an 80% load max you have about 200 watts to spare. and of course, when bidding, I really only know bulb watts. I really can only guess at what taps I would grab on which wire and so forth.

Tomwilllight
07-16-2010, 09:27 PM
I don't like to load a transformer more that 50 or 60% of rated load. The clients always want more and it's much simpler to give them more if you don't have to add a new transformer into your bid.

As for LEDs - we will save a lot of copper.

Tom

INTEGRA Bespoke Lighting
07-18-2010, 08:30 PM
Not trying to sidetrack the thread... but once you make the move to LED systems you will find you stop worrying about calculating excess capacity for your transformers. We are now doing complete property installations that run on less than 300W in total. My challenge has been to find quality transformers that are sized below 250-300 watts.

The best, neatest and trickest solution is the Q-hex transformers by Q-tran. http://www.q-tran.com/q-hex/
They are sized from 60W all the way up to 300W and offer 11v to 15v multi-tap flexibility. They are relatively small and very discreet when mounted into the Q-trix enclosures.

bcg
07-18-2010, 09:19 PM
James,

Are you using LED fixtures or putting LED lamps in traditional fixtures? What brand of products are you using? I see that Ushio now has some LED MR-16 lamps but they are only 4W right now. I believe Copper Moon had 4W and 8W MR-16 lamps but I'm having a hard time finding them. I held some in my hand last week but they belonged to someone else.

INTEGRA Bespoke Lighting
07-19-2010, 12:10 AM
I use my own line of LED lamps. We engineer, manufacture and distribute them. They have been specifically designed for use in outdoor lighting systems. I have tried most of the rest and was not impressed, so I built my own.

We are currently going through a re-branding process as I have new partners. We look forward to being sponsors here at Lawnsite in the very near future and will be able to provide you will full details then. Right around the time we launch our new line of miniature LED lamps along with our new 35W Halogen replacement LED lamp.

The future is bright for LED lamps!