Register free!
Search
 
     

Click for Weather
Reply
 
Thread Tools Display Modes
  #1  
Old 01-19-2009, 01:42 PM
jimmy1111 jimmy1111 is offline
LawnSite Member
 
Join Date: Jan 2009
Location: philadlephia, pa
Posts: 56
Low Voltage Transformer Trouble

Opened a VISTA STT 900 and found the secondary wires from the trans to the 3 breakers in pretty bad shape - corrosion, melted insulation, one wire completely melted.

The wires are 12AWG rated to 600V - I'm assuming low voltage wires. Can I replace them with regular 10AWG also reated for 600 V that I got from home depot as high voltage wires ?? isn't better wire since it is rated for high voltage power versus what vista seem to have installed low voltage wires knowing that on the secondary it is low voltage anyways ???

The other question, what could have caused this mess ?? had the Transformer for 4 years with 270 W at each circuit without any problems. I moved to a new place and and went to 290W for each of the 3 circuits....I know I should have stayed 10% of max capacity...but could this extra 20W on each circuit created this nightmare eventhough i'm still below the 300W threshold and this is a vista not a cheap transformer ??

Thanks.
Reply With Quote
  #2  
Old 01-19-2009, 10:21 PM
INTEGRA Bespoke Lighting's Avatar
INTEGRA Bespoke Lighting INTEGRA Bespoke Lighting is offline
LawnSite Gold Member
 
Join Date: Jun 2007
Location: Muskoka, Ontario, Canada
Posts: 3,936
Please tell me that you had more then one 12awg wire to each of the 3 circuits. It sounds as if you loaded 290W onto each of three 12 ga. wires. If this is the case, you have greatly over loaded the wire.

Jimmy... are you a contractor or a DIY'er?
__________________
James Solecki
INTEGRA ~ Bespoke Lighting Systems ®
JSLDesign Inc.


www.integralighting.com

www.facebook.com/INTEGRA.Lighting

Affiliations: IESNA, IALD, IDA, AOLP, LO, MBA
Reply With Quote
  #3  
Old 01-19-2009, 10:25 PM
TXNSLighting's Avatar
TXNSLighting TXNSLighting is offline
LawnSite Fanatic
 
Join Date: Feb 2007
Location: DFW, TX
Posts: 6,460
Sounds a little fishy, definately need more info and possibly pictures...
__________________
Ryan

Always a lesson, never a failure.

www.meangreenlawncare.com
Reply With Quote
  #4  
Old 01-20-2009, 12:27 AM
LightYourNight's Avatar
LightYourNight LightYourNight is offline
LawnSite Member
 
Join Date: Dec 2008
Location: Ann Arbor, MI
Posts: 101
i would call vista a cheap transformer... I replace them all day.

post some pics
__________________
John P. Cambruzzi
Landscape Lighting Specialist
Reply With Quote
  #5  
Old 01-20-2009, 02:12 AM
Mike M Mike M is offline
LawnSite Bronze Member
 
Join Date: Feb 2006
Location: South Carolina
Posts: 1,795
Does sound fishy.

Anywho, you measure the amps with a probe, don't worry about the watts, sounds like the load on the trans, and each wire, is over amped.

No mention of voltage taps. Bad grammar. It might be the bad grammar.
Reply With Quote
  #6  
Old 01-20-2009, 04:40 AM
David Gretzmier David Gretzmier is offline
LawnSite Gold Member
 
Join Date: Mar 2001
Location: Fayetteville,AR
Posts: 3,654
when wires melt, something is over amped, and probably the wires. 600v is rated for high voltage, but wires are rated by the amps they can hold at any voltage within thier range. 290 watts at 12 volts is actually 24 amps, and you need 8 guage to be safe from the trans to a close hub of at least 3 12 guage wires for EACH 290 watt run. most folks just run multiple 10-12 guage wire, loaded properly, into the trans and put multiple wire on the same tap.

I could go into what load those 12 guage lines could hold, but we've discussed it tons of times and I won't rehash it here, other than to say that a single 12 guage won't handle a 270 watt 12 volt load any day of the week.
__________________
freedom
Reply With Quote
  #7  
Old 01-20-2009, 07:49 AM
jimmy1111 jimmy1111 is offline
LawnSite Member
 
Join Date: Jan 2009
Location: philadlephia, pa
Posts: 56
well I didn't want to write a page in my first question so here is more details....2 of the three circuits are ran with 12 AWG Loops. so it is 2 12 AWG at each tap for these two circuits. The third circuit got also 2 12AWG wires running split in two sepearte directions. The STT 900 is a Multitap Transformer for 11, 12 & 13 Volts that VISTA stop making. The 13 V tap is the one that melted than i switched it to another circuit and that one started to get corroded and melting.

Is the rated amps of a wire labeled on the wires ? vista installed like 3 inch or so of these wires inside the transformer and I can't see the full label. I saw the 600 V. Is the low voltage wire capable of holding more amps than the same AWG of a High Voltage wire?

The other question i had was corrossion ? is it when the wires melt they get corroded or is it water / humidity creating the corrosion?...I can't see how the water goes in a VISTA stanless steel transformer.
Reply With Quote
  #8  
Old 01-20-2009, 08:15 AM
INTEGRA Bespoke Lighting's Avatar
INTEGRA Bespoke Lighting INTEGRA Bespoke Lighting is offline
LawnSite Gold Member
 
Join Date: Jun 2007
Location: Muskoka, Ontario, Canada
Posts: 3,936
Dude, you have overloaded the 12 gauge wire, pure and simple. I would suggest hiring a professional or at the very least taking a LV lighting installation seminar.

Regards.
__________________
James Solecki
INTEGRA ~ Bespoke Lighting Systems ®
JSLDesign Inc.


www.integralighting.com

www.facebook.com/INTEGRA.Lighting

Affiliations: IESNA, IALD, IDA, AOLP, LO, MBA
Reply With Quote
  #9  
Old 01-20-2009, 11:35 AM
jimmy1111 jimmy1111 is offline
LawnSite Member
 
Join Date: Jan 2009
Location: philadlephia, pa
Posts: 56
well...how much Amps a 12 AWG cable can hold ? isn't supposed to be written on the cable because I don't see it. Also; would having loops of 12 AWG is actually doubling the 7500 Cable Constant for the 12AWG cable, or in other words is it equivalent to say that I have the same load on 2 12AWG Wires? This is one part of the issue.

The second part which i don't seem to receive comments on but Dave got close is: Can a High Voltage 10 AWG wire be a substitute of a 12 AWG Low Voltage Wire that's inside the Transformer secondary side which is from the coil to the 25 Amp Breakers and than from the 3 Breakers to each Taps? If I overloaded why the 25 Amp breakers didn't trip ?
Reply With Quote
  #10  
Old 01-20-2009, 12:08 PM
TXNSLighting's Avatar
TXNSLighting TXNSLighting is offline
LawnSite Fanatic
 
Join Date: Feb 2007
Location: DFW, TX
Posts: 6,460
Man, you really need to hire a professional to fix this mess.
__________________
Ryan

Always a lesson, never a failure.

www.meangreenlawncare.com
Reply With Quote
Reply

Tags
landscape lighting , transformer , vista

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump






Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Copyright ©1998 - 2012, LawnSite.com™ - Moose River Media
All times are GMT -4. The time now is 08:19 AM.

Page generated in 0.11540 seconds with 8 queries