Spa Heater Contactor Overheating


  #1  
Old 10-05-10, 09:10 PM
E
Member
Thread Starter
Join Date: Oct 2009
Location: Puerto Rico
Posts: 9
Received 0 Votes on 0 Posts
Spa Heater Contactor Overheating

Hi everyone,

I have posted a water heater problem a year ago. Thanks to Ray & Marc, I solved the problem (kind of). But a new problem has arisen... : (

The wiring of my water heater / contactor is as follows:
1) The 2 x 110v power cables go to 1 end of the 220v 50 amp contactor (double pole).
2) The other end of the contactor, the cables go to the 220v 50 amp water heater.
3) 2 x 110v (thinner) cables go out from the power-in of the contactor and go straight to the 220v 40 amp timer.
4) 2 x 110v (thinner) cables go out from the timer and go straight back to the sides of the contactor.

Everything seemed to function well after the installation. When the settings of the timer kicked-in, the water heater turned on and off automatically. And the timer was no-longer overloaded.

Now however, this new addition is generating so much heat that the plastic insulation around all 4 x 110v cables near the contacts (of the contactor) melted, and the end of the copper cables became brittle.

It worked for about 4 months. Then 1 of the 110v power cable got so brittle and broke. So I cut the power cable shorter and exposed the fresh end to reconnect to the contactor.

After another 4 months, it happened again. I am not sure why the power cables accumulate so much heat. Does it have something to do with resistance? Besides, I found moisture accumulated inside the wall of the housing of the contactor, but not in the housing of the timer. How weird!

Also this evening I removed the contactor and connected all the power cables directly to heater. I put black tapes around the cables where they joined. After the heater was on for 2 hours, the black tapes got burnt and split.

Does any expert know why?

Here is my old post link if you need more info:

http://forum.doityourself.com/electr...r-dilemma.html

I will appreciate any input. Thanks.
 
  #2  
Old 10-05-10, 11:11 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
First of all, the voltages are 120 and 240 unless you are living way out in the sticks. Secondly, you are not feeding with two lower voltage circuits but one higher voltage circuit that MAY have a neutral lead in the mix.

Overheating of conductors and connections is either a sign of the conductors being too small, the connections being faulty or the load (the heater(s)) have a defect causing it to draw more amperage than normal. What size conductors are you using and what is the rating for the heater?
 
  #3  
Old 10-05-10, 11:32 PM
F
Member
Join Date: Mar 2006
Location: NE Wis / Paris France{ In France for now }
Posts: 4,807
Received 2 Votes on 2 Posts
Emeo.,

OK I can understand that and can you kindly post a photo for us then we can able figure it out what is going on and you may have to tell us all the conductor size { either in mm˛ or AWG size } then we can able find a soluation for you.

Merci.
Marc
 
  #4  
Old 10-05-10, 11:51 PM
ray2047's Avatar
Member
Join Date: Mar 2006
Location: USA
Posts: 33,575
Received 15 Votes on 13 Posts
For those who didn't read the original post Emeo had a spa on a timer but the current draw exceeded the timer's maximum current capacity. At the groups suggestion he added a relay between the timer and the spa. IIRC the relay coil was 120v. The relay was supplying 240v at 50a.

Then in this thread wrote:
1) The 2 x 110v power cables go to 1 end of the 220v 50 amp contactor (double pole).
But what he really means is he has 240v going to the contacts on the relay. He next wrote:
It worked for about 4 months. Then 1 of the 110v power cable got so brittle and broke. So I cut the power cable shorter and exposed the fresh end to reconnect to the contactor.
But I believe he means one leg of the 240v supply wires to the spa overheated.

Emeo, I believe you are confusing the new readers by referring to the legs of the 240v as 110v. The legs of a 240v supply are just that, 240 volts. They are not made up of two 110 or 120v lines.
 

Last edited by ray2047; 10-06-10 at 12:15 AM.
  #5  
Old 10-06-10, 08:33 AM
I
Forum Topic Moderator
Join Date: Feb 2005
Location: Near Lansing, Michigan
Posts: 10,941
Received 45 Votes on 43 Posts
Do you know which electrical code is followed in PR? Was the tub installed and inspected to code? Particularly the wire sizes?

Originally Posted by emeo2009 View Post
I am not sure why the power cables accumulate so much heat. Does it have something to do with resistance?
Yes. Bad connections have high resistance and overheat. Also wires that are too small for the load they supply have too high of resistance and overheat.

Besides, I found moisture accumulated inside the wall of the housing of the contactor, but not in the housing of the timer. How weird!
How much moisture? Did the wire terminals or any part of the contactor show signs of rust or corrosion?

I removed the contactor and connected all the power cables directly to heater.
How are they connected before they burned up? Wirenuts, screw terminals?
 
  #6  
Old 10-09-10, 08:47 PM
M
Member
Join Date: Jul 2009
Location: so cal
Posts: 283
Received 0 Votes on 0 Posts
over heating the wires

do you have access to a digital meter with amp probe clamp?

I'll bet you are drawing more than 50 amps or right at 50amps, and even though the main breaker may hold the load for 2 hours, I am thinking the wire size is under sized for the task given going to and from, the contactor since you mentioned you hooked it direct and got the tape burnt. Are the wires #8 THHN? are the terminals on the contactor rated at 75c?

is this your model of heater?

Hayward Spa Heater model CSPAXI11 11 KW @ 240 volts ( 45.8 or 46 amps rounded )


link to pdf for part provided below

http://www.google.com/url?sa=t&sourc...s6ldOg&cad=rja
 
  #7  
Old 10-09-10, 11:37 PM
F
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,495
Received 36 Votes on 28 Posts
If that is your heater then the problem is an undersized circuit. Circuits for heaters need to be sized for 125% of the full load current. 125% of 45.8 amperes is 57.25 amperes, clearly a 50 ampere circuit is too small.

EVERYTHING from the branch circuit breaker to the wiring to the contactor and all connections need to be sized for 60 amperes.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: