Electrical Repair Questions? Ask an Electrician for Answers ASAP
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1) What type of appliance is this? Does the appliance have a motor? If a motor, can you provide me with the nameplate rating on the motor or possibly post a picture of the nameplate? If an appliance with a motor, I need to know the FLA (Full Load Current) rating?
2) You mention a 120/240 breaker. Are you connecting this to a full size single pole or a double pole breaker or a mini or tandem breaker?
3) If the appliance requires 26.3 amps and you are connecting it to an existing 20 amp circuit that is shared with another connected load, then yes, the 20 amp breaker is doing its job and it will trip since the 26.3 amps of the appliance has exceeded the 20 amp breaker rating by 6.3 amps.
4) If connecting the appliance to an existing 30 amp breaker and the appliance requires 26.3 amps, then you only have 30 minus 26.3 amps available or 3.7 amps available. If the other connected load exceeds 3.7 amps, then yes, the breaker will trip since the load is shared.
1. fisher scientific 2245g hotplate2. double pole square d
3. yes this i understand.
4. the breaker that tripped is on the appliance, not in the cabinet. the cabinet breaker never tripped. the appliance breaker trips immediately. when i put a meter on the supply at the appliance it read 208V. so the appliance is getting 208 up to 30 amp. there is nothing else connected to that circuit. what i dont get is how do i change that to 110 at the appliance...i thought that with a 120/240 breaker it would work fine. this circuit is an old circuit that was for an electric heater in that room. i disconnected the heater and ran the existing wire (it was in a flex conduit) over to where we want the hot plate and hard wired it to the hotplate.
1) Thank you for the replies.
2) Is the hotplate application for a single family dwelling or a commercial application? The reason I'm asking is that 208 volts is 3-phase voltage and not single phase. 3-phase 208 voltage is typically only located in commercial and/or industrial locations and not in a single family dwelling. Single family dwellings are 120 and 240 volt single phase delivered from the electrical utility unless the voltage was altered on-site by a transformer.
3) You mention the hotplate is rated @ 110 volts and @ 26.3 amps. This means that the required voltage for this appliance needs to be on a dedicated 120 volt single pole 30 amp breaker and not shared with any other connected loads. If terminating the conductors to the Square D Double Pole full size breaker (see bottom picture below), that breaker is 240 volts and NOT 120 volts. I am unable to locate this particular model number on the Fisher Scientific website.
4) The only type of breaker that provides both 120 and 240 volts is called a Quad type of breaker where it will have 2 single poles and 1 double pole breaker all combined into a quad breaker. If the breaker is a full size single pole breaker, it will always be 120 volts. If a full size double pole breaker, it will always be 240 volts. If a tandem or mini breaker, each half will be 120 volts since a tandem is actually 2 separate single pole's combined into 1 full size.
Here is a picture of a Quad breaker:
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Here is a picture of a Double Pole breaker: Is this the type of breaker you have?
1) You mention the following:
"I tried connecting it to a circuit with 20 amp 120/240 breaker and it trips the breaker in the panel"
2) I assume the panel is your main electrical panel circuit breaker? Please confirm.
2. yes it is the main panel. we have two panels each with its own feed. the warehouse panle is seperate from the office panel.
1) Since you are measuring 208 volts and this is located in a warehouse, you have 3-phase service from your local electrical utility or the warehouse is using customer premise transformers. Since the hotplate is rated @ 120 volts, you cannot connect this appliance to a 208VAC 3-Phase circuit. A 208 VAC 3-phase circuit breaker is actually 3 full sized circuit breakers all combined into 1. Most likely you have a 3-phase panel in the warehouse for things like motors or roof top HVAC units, etc. The office panel is more than likely the 120/240 VAC single phase panel. Since the hotplate is rated at 120 volts, you need a dedicated 120 volt, 30 amp single pole breaker (NOT a double pole) run from the office panel to the appliance location. Double check the office panel and most likely it will be 120 and 240 volts and not 208.
2) Since using a 30 amp breaker @ 120 volts, the maximum distance from the electrical panel out to the appliance location can be 50 feet based on using 10 AWG Stranded Copper Type THHN insulation. Code recommends a maximum of a 3% voltage drop on a circuit. The 50 feet @ 120VAC and 30 amps results in 3% or 3.6 volts drop. Therefore, acceptable. If the distance is greater than 50 feet, then the hot and neutral conductors need to be increased in order to compensate for a larger voltage drop.
Hope this helps.........If you have any additional questions, let me know and I'll be glad to answer them for you.
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So is the solution to just swap the breaker at the panel with a single pole 30 amp breaker. The wiring is blue and a black. would the blue get hooked up where the white wires go? there are both single pole and double pole breakers in this panel.
Or are you saying i need to run new wiring with a new breaker?
1) All 120 volt circuits require 1 hot wire, 1 white neutral wire and 1 equipment ground. The hot wire is typically a black wire or it can be blue. The equipment ground will be the EMT or Rigid conduit since this is a warehouse environment. The conduit will need either the 1 black or the 1 blue for the hot and 1 white for the neutral. You can leave the existing blue wire inside the conduit if you wish and just cap it off at both ends with a wire nut or you may remove the blue wire. Either way, you need 1 white wire for the neutral conductor. It may be easier to run new wires inside the conduit. Just depends on how many other existing wires, pull boxes and/or splice boxes are along the conduit path.
2) Depends what panel that the circuit originates from. If originating from a 208, 3-Phase panel, check the hot bus bar slot position using an AC volt meter. Check for 120 volts from 1 hot slot position to the neutral bus bar. If good measuring 120 volts, then use a 30 amp single pole breaker in that position. As I mentioned last night, if a 208 panel, you may not have any 120 volt slots left since the 208 3-phase breakers take up the majority of the slots in this type of panel. Depends on how the 208 panel was originally configured and if any available breaker positions. See below for originating the circuit out of a 120/240 panel.
3) You may need to originate the circuit out of a traditional 120/240 volt single phase panel such as the one located in the office area. If so, same thing as the 208 panel. Use a 30 amp single pole breaker. Land the hot black wire on the 30 amp single pole breaker and land the white neutral wire onto the panel's main neutral bus bar.
Yes in order for the hotplate to work, you need a 30 amp single pole circuit breaker that will provide the hot conductor with 120 volts.
DO NOT use a double pole breaker as this type is 240 volts and a good chance of destroying the hot plate if used.
Otherwise, don't forget to rate me before you log Off.
The next time you have an electrical question, you can also request for me at:http://www.justanswer.com/home-improvement/expert-your-electrician ..........Thanks..............Kevin!
Thank you for the positive service rating.................much appreciated!
Take care and have a great weekend..............Thanks.............Kevin!