# bryant low voltage light switches troubleshooting



## frenchelectrican (Mar 15, 2007)

RICK BOYD said:


> bryant low voltage light switches,
> how to troubleshoot ?
> 
> lights in house won't turn off
> ...


It can be any one of combation but most common is either switch or relay is useally the curpit.,

but if all the LV switch fail to work then more likely transformer failed.

those LV switching circuits are typically wired on 24 V AC but few do run on 24V DC ( only reason used DC is keep the buzzing noise out of equation )

the only time LV cable will fail if idiot homeowner drove a large arse nail or screw in the wall and hit the cable.


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## splatz (May 23, 2015)

I'd say the relay is the best place to start troubleshooting, see what happens with the control wires lifted and / or the hots lifted from the contact terminals.


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## telsa (May 22, 2015)

Start with sticking switches.

You can spot them without even taking the plates off -- as they will visibly stick.

If it's the transformer... many, many lights will be affected.

A stuck relay won't have such wide spread impact.


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## inetdog (Apr 13, 2016)

frenchelectrican said:


> but if all the LV switch fail to work then more likely transformer failed....


The reason being that most systems use mechanically latching relays for the branches. The LV switches are momentary to cause the relay to change state. 

With the LV source gone the relays will stay in their last state even if you cycle power to the whole system.

Sent from my XT1585 using Tapatalk


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## Rodger (Jan 3, 2017)

telsa said:


> If it's the transformer... many, many lights will be affected.
> 
> A stuck relay won't have such wide spread impact.


Correct! Most residential installs of this type that I've seen only have one or two transformers for the whole house. My own experience would suspect a sticking relay, but a week output from the transformer can cause some relays to not work while others will. That being said, these old transformers usually don't give up with out making a buzzing racket you can hear when you stick your head in the attic, and I've only found two of them to be bad. The relay are more common to go out than switches but both fail. However the switch is easy to test without hunting down the relay. 

Some Houses have the relays distributed in J-boxes all over the attic and crawl space (I hate those). Others (the easy ones to work on) have central locations for relay panels. The ones with panels will often include the transformer in close proximity.

Ether way, I start with the switch.

Look for physical damage, contamination or sticking. Replace switch if found.

Not found: remove the switch and momentarily short the wires in an attempt to manually operate the relay. Replace switch if relay functions manually. 

Relay not responding: Check voltage at the switch leads. If low check voltage at transformer. (Note: A low system voltage can also be caused by a sticking switch or short somewhere else in the low voltage circuit)

Transformer Voltage Bad: Check 120V connections and replace transformer if needed.

Transformer Voltage Good: Wiring damaged or stuck switch on the circuit.

Voltage good at switch: Locate and test relay. If the relay is good then there is a problem with the wiring.

I used to test current at the switch too, but then I ran into a few electronic relays. These don't draw nearly as much current at the typical mechanical relay and they also don't click or buzz to help you locate them under the attic insulation.

Good luck. :bangin:


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## RICK BOYD (Mar 10, 2008)

I think the switch was stuck which caused the relay to burn out ,
fixed the switch replaced the relay , 


all better now


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## RICK BOYD (Mar 10, 2008)

*found the problem*

outside low volt sw under a cover that was crooked 
held the sw in activated state and burned the relay out
fixed the cover, replaced the relay. A-OK now

lights in house won't turn off 

switch? relay ? bad transformer ? what other possibilities ?[/QUOTE]


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## telsa (May 22, 2015)

RICK BOYD said:


> outside low volt sw under a cover that was crooked
> held the sw in activated state and burned the relay out
> fixed the cover, replaced the relay. A-OK now
> 
> ...


You've nailed all three faults.

Jump back in.

If the ENTIRE house is 'frozen' then the transformer is where you start.


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## macmikeman (Jan 23, 2007)

frenchelectrican said:


> the *only time* LV cable will fail if idiot homeowner drove a large arse nail or screw in the wall and hit the cable.



Incorrect. Lots of old relay lighting systems , at least the ones they did around here used twisted red/white doorbell wire for the pilot legs to the switch relays. After so many decades the insulation has dried out and cracked and fallen away. I get calls maybe two or three times a year about this. Some places I just rewired the lighting to normal 120 volts, but a few I ran new two wire cables with an outer sheath to replace the old. But that is hard to do when the existing was run in shallow chases cut into the door frames and buried under the door stile to get it down to the switches and remain concealed. It's all no fun to repair.


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