Archive for the ‘Electrical’ Category

Submersible pumps – 2 or 3 wire?

June 1, 2011

Submersible Water Pumps, 2 or 3 Wire.  What is the Difference?

 Submersible pumps, the kind of pump that goes in your well or cistern, are available with two wire motors or three wire motors.  There is also another ground wire which is not counted, so if you look at the pump the actual number of wires will be three or four.  The two wire pump will have two black wires and one green ground wire.  The three wire pump has a black, red, yellow and green wire.

You are probably thinking, “That’s nice, but what is the difference to me?”  The main difference is the three wire pump uses a separate control box which includes a capacitor and relay to start the pump.  The control box is located inside your house or pump house.   The two wire pump does not use a control box.  Everything is built inside the motor of the pump.  All motors larger than 1 ½ HP are only available in the three wire version because you need the control box to start the heavier motors.  Most residential pumps are smaller horsepower.  Our top selling pump is just ½ HP.

Many years ago we sold mostly three wire pumps.  We believed that having a separate control box above the well would sometimes save people the time and expense of pulling the pump when they experience a problem.  If the problem is in the control box it is a simple and relatively inexpensive fix to replace the box, as opposed to pulling the pump and replacing the motor or whole pump.  This is the main advantage of the three wire pump.  Then, probably 25 years ago, a local plumbing contractor insisted he had far fewer problems with two wire pump systems.  We slowly shifted to selling more two wire pumps and our experience seemed to agree with the contractor’s observations.  Also, two wire pumps are less expensive, the wire used to install them is less expensive and the installation is easier because you do not have to wire through the control box.  Of the pumps we now sell, at least 90% of them are two wire.

Advertisements

Which size wire and breaker do I need for an electric water heater?

May 31, 2011

Which size wire and breaker do I need for an electric water heater? 

The wire and breaker size depend on which heating elements are in your water heater.  Find the watt rating  for the elements.  This rating is usually on a tag on the side of the water heater.  It is also printed on the elements.  You can find the elements on the side of the heater under a plate attached with one or two screws.

For elements up to and including 2500 watts, the minimum wire size would be 12 gauge.  With 12 gauge wire, use a 20 amp breaker or fuse.  For elements over 2500 watts you must use 10 gauge wire and a 30 amp breaker or fuse.   It is important to match the wire size to the correct breaker or fuse.  The breaker protects the wire from overheating.  You can use 10 gauge wire for lower wattage water heaters.  If you are running wire for a new water heater, it is a good idea to use 10 gauge so that you are covered for any water heater you might buy in the future.

You can find wire on our web site at: http://keithspecialty.com/elec.cable_wire.htm

Electric Hot Water Heater – Elements

May 14, 2011

How Do I Determine Which Element I Need for My Electric Water Heater?

 If you run out of hot water faster than you used to, have only lukewarm water or no hot water at all, it is possible that one of the elements needs to be replaced. How to accurately diagnose a faulty element is a topic of another post.  This post assumes you have already determined that you need new elements.  It discusses how to determine which element you need and how to replace them.

There are two types of elements found in the majority of water heaters:   a flanged element or a screw-in threaded element.  There are some other types on older heaters, but they are becoming very rare.

Flanged hot water element Flanged Element 

Screw in hot water element Screw-in Element           

Hot Water Element socket wrench Socket Wrench

                                                                    

Always turn off the power supply to the water heater and drain the water from the tank before working with the elements.  Most water heaters have two elements while some have only one.  The elements are located on the side of the tank behind a metal plate attached with one or two screws.  Remove the plate.  There will be two wires attached to the element.  Loosen the screws and remove the wires.  Don’t worry about remembering which wire went to each screw, it doesn’t matter.  It will now be obvious which element you have.  If you see four bolts, it is a flanged element.  Remove the bolts and pull the element straight out.  If you have a screw-in element, you will see a single large hex head on the element.  A 1 ½” deep socket can be used to remove the element or you can purchase an element socket wrench.

The wattage and voltage will be printed on the head of the element.  Some elements will have two different listings such as 3500W at 208V and 4500W at 240V.  Use the larger number when ordering.  You may want to replace both elements while you have the tank drained, even if only one is bad now.

Important reminder!  After installing the new element, always refill the tank with water before turning the power back on.  Open a faucet while you fill the tank to be sure there are no air pockets remaining inside the water heater.  Since elements are made to be submersed in water, they will burn out in seconds if you turn on the power to the tank before it fills completely.

 

Other informational sources:

  •  A diagram of hot water tanks – from HowStuffWorks.com
  • Good video on replacing an element.  Note: this video does not discuss filling the tank with water before turning on the elements.
  • Another source of how to change an element from Ehow.com