wptski
Senior Member
- Location
- Warren, MI
A while back had a relative ask me to help them with their under cabinet lighting as some went out. Having never worked on them before, I found out they were 12V and the transformers were in the basement.
One was cold and the other warm, no skills required but as I remember, I put an amp meter on the input wires to verify. Later when they received the part, I went back to install it.
They contacted me that the other bank went out, they discovered that the other transformer is bad and have a new one. I later found out that a friend electrician used a clamp meter that I gave them the last time to replace the defective part.
They said the power was OFF. I used a Fluke VoltAlert, no power. Breaker ON, still no chirping, verify chirp at another circuit. Pull the twist caps OFF, use a T+ Pro, no power. Use a 87V, still no power. Use an extension cord from another circuit, still shows no power. Breaker OFF, other working lights go OFF as well. Disconnected both transformer wires, VoltAlert chirps, 87V and T+ Pro show power.
I connected the new transformer and all is well.
Connected the bad one at home, VoltAlert chirps and the T+ Pro reads 120V.
I did a search later and these so-called transformers are really electronic power supplies with a HF 12V output, on some there is no output without at least a 20W load and its output can only be read correctly with a RMS DMM .
Not sure what would fool the VoltAlert, etc. but one transformer was from the original install years ago done by the previous home owner.
Anybody have a logical reason for what I described here? When something can fool a VoltAlert, T+ Pro and a 87V, it’s a good way to end up touching a hot wire!!
I wish that I would have at least tried to use the VoltAlert with the new transformer installed.
One was cold and the other warm, no skills required but as I remember, I put an amp meter on the input wires to verify. Later when they received the part, I went back to install it.
They contacted me that the other bank went out, they discovered that the other transformer is bad and have a new one. I later found out that a friend electrician used a clamp meter that I gave them the last time to replace the defective part.
They said the power was OFF. I used a Fluke VoltAlert, no power. Breaker ON, still no chirping, verify chirp at another circuit. Pull the twist caps OFF, use a T+ Pro, no power. Use a 87V, still no power. Use an extension cord from another circuit, still shows no power. Breaker OFF, other working lights go OFF as well. Disconnected both transformer wires, VoltAlert chirps, 87V and T+ Pro show power.
I connected the new transformer and all is well.
Connected the bad one at home, VoltAlert chirps and the T+ Pro reads 120V.
I did a search later and these so-called transformers are really electronic power supplies with a HF 12V output, on some there is no output without at least a 20W load and its output can only be read correctly with a RMS DMM .
Not sure what would fool the VoltAlert, etc. but one transformer was from the original install years ago done by the previous home owner.
Anybody have a logical reason for what I described here? When something can fool a VoltAlert, T+ Pro and a 87V, it’s a good way to end up touching a hot wire!!
I wish that I would have at least tried to use the VoltAlert with the new transformer installed.
