Thread: Transformer panel for electric baseboard heat

Why did they use transformers for electric baseboard heat?
The transformer panel which is in the attic has a humming noise that can be heard in the bedrooms below.

Not sure why they used transformers, but transformers are made by stacking thin steel plates together to make the core for the winding the wire around, those thin steel plates are referred to as laminations and they have a tendency to vibrate with the magnetic lines of flux which are created within the transformer.

Those vibrations are the cause of the humming noises transformers make.

A transformer will buzz loudly when it is faulty. The metal housing is amplifying the sound, maybe.

The transformers are probably for low voltage thermostats. Replace the one that is buzzing.
It is too hot up in the attic for transformers. The coating on the leaves has melted so now it's metal to metal. They say a doorbell transformer should not be installed in the attic because of the heat factor. Same would be true for the thermostat transformers. They are essentially the same, and cheap to replace.

Originally Posted by Jim Abram

.... , it is appropriate to ascertain that electric heat thermostats are not line voltage.

Jim, sorry, but I have to disagree with you.

Shop Fahrenheat Rectangle Mechanical Non-Programmable Thermostat at Lowes.com

I'd sure like to see these transformers.

Originally Posted by Brad Richter

I'd sure like to see these transformers.

I can't show you the OP's or Jim's but here's a couple of pics, some thermostat power supplies in a crawl, a doorbell ringer in an attic.

Originally Posted by Jim Abram

The issue with line voltage thermostats is that they require GFCI protection in wet locations.

They do?

Why?

What requires GFCI for those transformers? I may have missed that requirement?

Question: I sometimes run into an older home where the doorbell transformer is actually inside the Service Panel. What do some of you write about it in your reports? Is it wrong? Was it / is it still permitted?


Thanks,
Jim

Originally Posted by Jim Hintz

Question: I sometimes run into an older home where the doorbell transformer is actually inside the Service Panel. What do some of you write about it in your reports? Is it wrong? Was it / is it still permitted

Jim,

That is not permitted, nor has it been permitted in the recallable (is that a word? ) past.

There typically is a mounting hub (threaded or a screw assisted retaining device) which is designed to be, and permitted to be, installed through a knockout with the 120 volt supply conductors inside the panel (or inside a box) with the low voltage terminals and the transformer outside the panel or box.

Originally Posted by Jerry Peck

Jim,

That is not permitted, nor has it been permitted in the recallable (is that a word? ) past.

There typically is a mounting hub (threaded or a screw assisted retaining device) which is designed to be, and permitted to be, installed through a knockout with the 120 volt supply conductors inside the panel (or inside a box) with the low voltage terminals and the transformer outside the panel or box.

Thank You Jerry, I can always count on you....

I too would like a code cite for the GFI protection for the transformers in a bathroom.

Originally Posted by Jim Abram

Thermostats not transformers

Circuit Breaker (Overcurrent Protection)
SlabHeat installations must be protected against overload by a circuit breaker. GFCI type
(ground fault circuit interrupter) or AFCI type (arc-fault circuit interrupter) breakers may be used
if desired, but are not necessary when using SunStat controls with integral GFCI.

Since the OP asked about baseboard heat I don't see how this applies.

Originally Posted by Jim Abram

The issue with line voltage thermostats is that they require GFCI protection in wet locations.The GFCI protection is often overlooked especially in older installations .

I am still waiting for the code which requires the above stated GFCI protection ...

[
ThQUOTE=John Kogel;241408]A transformer will buzz loudly when it is faulty. The metal housing is amplifying the sound, maybe.

All mechanical xfrm's hum to some degree.
There are more than one reason for this such as eddy currents etc.
The DB varies according to; HZ, load, primary vs secondary voltage and current difference, and construction as JP mentioned.
So to simply state that noisy/buzzy ones are defective is not necessarily true. I've installed some monsters and some mice but have to admit that the small units used for door bells and the like are virtually silent. Unless their not secure to their panel/box.

Originally Posted by Jim Abram

You must of missed it at #16. Manufacturers specifications

Nope, I didn't miss #16 - there is nothing there stating that was anything other than your opinion.

For posts to be meaningful, when code or manufacturer' instructions are referenced one needs to state what the information represents, and, if it is a quote then one needs to indicate that in some recognizable way.

That would solve the puzzle of what information is intended to represent.

Thanks in advance for including such in the future.

Originally Posted by Jim Abram

Thermostats not transformers

Circuit Breaker (Overcurrent Protection)
SlabHeat installations must be protected against overload by a circuit breaker. GFCI type
(ground fault circuit interrupter) or AFCI type (arc-fault circuit interrupter) breakers may be used
if desired, but are not necessary when using SunStat controls with integral GFCI.

I just did some Nutone floor mats in a bathroom and the provided t-stat is gfi protected and line voltage, 120 or 240volt. (not low voltage) No such GFI requirement for baseboard heat. Even in ground pool electric heat has no GFI requirement. NEC 680-9