208 single phase load

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monkey

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A customer has a 208 single phase toaster. His service is 4 wire Delta 120/240 (208 high leg). Since there is 240 between phases, the only way to get 208 is from the high leg to ground. Can the toaster be connected this way or did he buy the wrong toaster?

The unit is plug and cord connected with a Nema 6-20, so you would think it would work ok on 240 L-L, but it does have a motor and that would put the voltage over the 10% rating.
 
The question is, can you locate a single pole circuit breaker rated for a 208 line-to-neutral voltage?

Tell the customer they are too serious about their toast. Buy a more appropriate toaster. :D
 
The 1-pole circuit breaker needs to be rated for 208 VAC. Breakers are rated at 120, , 208/120, 120/240, and 240 (UL 489). The situation you're talking about needs a 240 rating, as the dual ratings are for 2 and 3-pole breakers.

I'd suggest a call to the manufacturer to see if the equipment will handle 240. If not, then either get the correct equipment or use a transformer, which is getting pricey.

Goodluck
 
chicar said:
Do you mean 208 single phase 2 pole,or 208 single circiut?
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He meant a single pole 208 volt circuit which is from the B phase to the grounded conductor. A 2 pole CB would give him 240 volts phase to phase. I've never seen a single pole CB rated for 208 volts.
 
There are many 1 pole breakers that can be used on 208V to ground systems. Actually, they are rated for 277V. :wink:
 
If this 208v rated toaster was 13.5 amps or less,It should still be ok on a 240v rated circuit. The increased wattage due to the increased voltage would be under the 16a limit.
Rick
 
Paul, I was finally able to contact a representative and he said yes, it will be ok on 240. It didn't say it on the nameplate though, so I was leary. Anyway it is working fine on 240, putting out 800 slices per hour.

I was my understanding most circuit breakers are rated at jim says.
 
monkey said:
A customer has a 208 single phase toaster. His service is 4 wire Delta 120/240 (208 high leg). Since there is 240 between phases, the only way to get 208 is from the high leg to ground. Can the toaster be connected this way or did he buy the wrong toaster?

The "High Leg" voltages should "NOT" be used for phase to neutral connections. Remember that the tap between the a-c phase that creates the neutral lead is not totally "in-phase" with the B or High Leg phase. Using a connection between B or High Leg and the neutral tap will cause overheating and possible harmonics development in the circuit. It will also cause undue strain on the insulating materials used in the transformer windings.
The same is true with the use of any High Leg phase to neutral combination on any Delta system. Do Not Use!!!!

BigdogClancy
BSEE, Licensed Master Electrician, Good old boy just trying to help.
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