Electrical – Wiring to Water Heater not getting 240v

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The wiring to my Water Heater is not getting 240v, and the Water Heater won't work.

I've tested the wires at the Water Heater (touching black to Black, and red to red on my electric meter) and I get 112v.

I then tested the breaker at the box. It is a two-pole breaker (is that the right name?) 2 120v breakers connected together (30a each). I touched the red lead from my meter to the connecting screw and the black lead to the ground and got:

Top breaker – 125v
Bottom breaker – 5v

I then touched one less to the to breaker and the other lead to the bottom breaker and got 112v (which is the same in getting at the Water Heater).

Does that mean that the bottom breaker is "no good"? And it should be replaced?

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UPDATE#1

Thank you for your answers/comments, I'll try to give more info.

I have power throughout the house. I just replaced the water heater (the previous one was old and started leaking).

The water heater breaker is in the 2nd and 3rd slots from the top of the right hand side. I tested that one as follows.

  • One lead to the top screw, other lead to the ground screw (125v).
  • One lead to the bottom screw, other lead to the ground screw (5v)
  • One lead to the top screw, other lead to the bottom screw (+/- 112v)

UPDATE#2

So I changed the breaker and managed to not electrocute myself, so that's a big plus!

I tested the connections at the breaker and I'm getting the following:

  • One lead to the top screw, other lead to the ground screw (125v).
  • One lead to the bottom screw, other lead to the ground screw (125v)
  • One lead to the top screw, other lead to the bottom screw (250v)

So I'm thinking that everything should be working fine now, BUT it is not.

Now, at the water heater, I'm only getting 85v. What could be the problem now?

thanks.

UPDATE #3

Harper, I believe that they are the same wires. I replaced them exactly as they were before, and I wired them at the water heater like the previous one was wired (both wires are red, and I put black electrical tape to the one connected to the common to make sure I did everything like it was done before).

Question: Does this mean I have to change the wires to the water heater? If so, is there a way to do it without tearing apart the whole house? I'm beginning to think this is going beyond my capabilities.

Best Answer

With only 5v on the bottom breaker I would turn them off and then pull the breaker and look at the buss terminals. Are they bright and shiny, or possibly melted away?

Inspect the breakers also; if no damage is found with the breaker out of the panel, close it and measure the resistance from where the wires connect to the back of the breaker. This should be very low, close to zero. If the reading is high the breaker may be bad.

As a possible temporary quick fix, cycle the breaker 10+ times on/off. Many times this clears carbon arcing and reseats the hammers, check resistance, if it dropped the breaker will usually work for a while (until you get a replacement).

If the breaker still shows a high or open resistance and no pitting or arcing on the buss bar, replace the breaker.

Make sure to always open or turn off a breaker prior to removing or installing so there is less chance of an arc flash.

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