Electric Furnace Sequencers

Did an inspection today where the bus bar in the electrical panel was scorched just below the electric furnace breakers. Home owner commented that the breakers were relocated because of arcing damage in that area.

When inspecting the furnace I notice that all 5 electric elements were on within the span of 30 seconds (time to walk upstairs, turn up the thermostat and back down in the basement)…

In your opinion, do you think that having all 5 elements turn on at once resulted in a power surge which damaged the bus bar at breakers? I think yes but…

My recommendation was to have a qualified electrician repair the furnace (most likely damaged sequencers) and for recommendation regarding the damaged electrical panel bus bar.

How do you know they all came on at once if you where upstairs somewhere?

No, I don’t think you will have a surge to do that damage.
They are resistance loads and just like your tail lights come on slowly.

I can’t see your sequencers in the photo flash…
They normally do not all come on at once as they have their own separate heaters.

Sequencers usually take about 30 seconds each to come on and there was 5 of them so they shouldn’t have all been on within 30 seconds which was the time it took to walk upstairs to turn the thermostat up and back downstairs.

They normally do not all come on at once but what if they were defective and did…

There was a few laying around the furnace which indicates that they were having problems with them prior…

Also two of the three breakers at the furnace were turned off which may indicate that there was a problem.

I think you’re way off base.

Even if they came on all at once, the spike may cause the breaker to trip-not cause damage to the panel.

I can not see your sequencer usually on five elements there would be two sequencers I would have looked at the wiring diagram if present which would have indicated if someone had modified the factory install as for the buss bar I am thinking loose connections. That is what IR is for;-)

The IR would not have shown anything because they replaced the breakers and re positioned them above the damage area.
I’ll ask the client to let me know what the electrician did.
Thanks everyone for your comments!

You don’t have five sequencers, there are only three there. ?

Also how did you determine they were on?

Correct but with multiple elements the sequencers can have first and second stages and I can not see in the pic how it is wired

l tested the elements with an clamp on amp meter and they were all on (~5KW each).

Yipper a 5 KW element draws 20 to 21 amps each, makes the old electric meter spin;-)

There is a fourth one on the left below the first row of three, just saying.

Sorry for the bad pic!