Us/european wiring compatibility

Reply

  #1  
Old 05-14-12, 06:24 PM
Member
Thread Starter
Join Date: Apr 2012
Posts: 3
Received 0 Votes on 0 Posts
US / European Wiring Compatibility

I'm trying to determine correct (safe) wiring for an Italian-made induction furnace rated at 220 VAC, 12 A continuous draw, Single Phase, 50/60 Hz. A 240 VAC, 20 A circuit should be adequate for a 18-20 ft feeder line connecting a 9 ft furnace pigtale at a safety disconnect switch. My concern is the wire sizes. #12 AWG solid cable with a 0.80" dia. is standard for the 20 A circuit. However, the pigtail coming off the furnace is braided wire measuring 0.115" dia. Are these wire sized compatible or should I increase the feeder line from the 20 A circuit breaker to #10 AWG? (Or, rewire the furnace pigtail to #12 AWG) If so, will the 20A breaker still be effective for safe operation of the furnace?
 
Sponsored Links
  #2  
Old 05-14-12, 06:40 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,493
Received 33 Votes on 25 Posts
Running a 220 volt device on 240 volts may decrease the life of the unit. I suggest getting more information on the oven, especially if running on a 240 volt supply might be detrimental. If it is, then use either a 16 volt or 24 volt buck/boost transformer of the appropriate VA size to lower the voltage.

It is extremely unlikely that the wires on the oven are braided but are instead stranded. They have been sized, and use an insulation appropriate to the unit, so no changes are necessary. Use standard #12 conductors for the branch circuit wiring.
 
  #3  
Old 05-14-12, 07:54 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Received 1 Vote on 1 Post
I'm trying to determine correct (safe) wiring for an Italian-made induction furnace rated at 220 VAC, 12 A continuous draw, Single Phase, 50/60 Hz. A 240 VAC, 20 A circuit should be adequate...
Yes. Especially since it's designed for 60 Hz as well as 50. (220V and 240V are within 10% of each other - it should make no difference.)
 
  #4  
Old 05-15-12, 05:02 PM
Member
Thread Starter
Join Date: Apr 2012
Posts: 3
Received 0 Votes on 0 Posts
Thanks for your input. I didn't think I needed a transformer either because of the 50/60 Hz design with the voltages being so close (The furnace spec. plate indicates 230 VAC but a tag on the pigtail specifies 220 VAC). I also think that a difference of .035" in the wiring diameters is also minimal especially with the larger wire being stranded. Just curious - is the 10% guideline NEC or an industry thumbnail?
 
  #5  
Old 05-15-12, 05:50 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Received 1 Vote on 1 Post
Just curious - is the 10% guideline NEC or an industry thumbnail?
I'm not sure where it originates; it's just something that I, and many of us, have relied on for years without a backfire. Others may have a specific answer.
 
  #6  
Old 05-15-12, 07:24 PM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,493
Received 33 Votes on 25 Posts
If this were an oven either made in the US or made for use in the US I wouldn't be concerned all that much about voltage. BUT European voltages are different than in the US. (Where's Marc when we need him?)

240 volts is the nominal voltage in the US; apply the +/- 10% rule and you get a range of 216 to 264 volts. That means that depending on the distance from the power plant and various transformers and the last distribution transformer before your home or shop AND the load of all the neighbors and your own load the voltage at the input of this device could be anywhere in that range. Let's assume that the voltage is on the high end, 264 volts.

Now, let us also make the assumption that European, or specifically, Italian, electrical devices are made to operate at a much closer tolerance, say 5% +/- of the rated voltage. (I have no idea of what the tolerance is for European equipment or power supply might be.) 5% over 220 volts is 231 volts. Heck, even 10% over would be only 242 volts but you have (theoretically) 264 volts. How long will a piece of equipment last that is designed for a maximum of 231 (or 242) volts last if supplied 264 volts?

Maybe the tolerance is wide enough to allow for the difference between European (Italian) nominal supply and US nominal supply, or maybe it isn't. That is why I suggest asking the manufacturer if using it on a US standard is acceptable.

I occasionally work with a piece of older equipment that was originally rated for operation at 440-460 volts. The substation supplying this load is delivering about 506 volts and we DO seem to have an inordinate number of failures of heating elements and contactor coils. Maybe just old age or maybe it's the higher voltage or maybe a combination of the two.
 
  #7  
Old 05-15-12, 08:02 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Received 1 Vote on 1 Post
let us also make the assumption that European, or specifically, Italian, electrical devices are made to operate at a much closer tolerance, say 5% +/- of the rated voltage. (I have no idea of what the tolerance is for European equipment or power supply might be.) 5% over 220 volts is 231 volts. Heck, even 10% over would be only 242 volts but you have (theoretically) 264 volts. How long will a piece of equipment last that is designed for a maximum of 231 (or 242) volts last if supplied 264 volts?
FWIW, I have never experienced a problem with equipment after hooking it up to anything resembling 240V, if it had a spec within range.

208V - no problems either. As in, will a 240V spec work on 208V? Yep. Maybe a tad slower or cooler, but not enough to matter.
 
  #8  
Old 05-15-12, 08:12 PM
Member
Join Date: Aug 2009
Location: USA
Posts: 4,947
Received 0 Votes on 0 Posts
Courtesy of Wikipedia: "Following voltage harmonization, electricity supplies within the European Union are now nominally 230 V 6% at 50 Hz.[1] For a transition period (19952008), countries that had previously used 220 V changed to a narrower asymmetric tolerance range of 230 V +6% −10% and those (like the UK) that had previously used 240 V changed to 230 V +10% −6%.[2] No change in voltage is required by either system as both 220 V and 240 V fall within the lower 230 V tolerance bands (230 V 6%). In practice, this allows countries to continue to supply the same voltage (220 or 240 V), at least until existing supply transformers are replaced. Equipment used in these countries is designed to accept any voltage within the specified range."

AS is this: "A distinction should be made between the voltage at the point of supply (nominal system voltage) and the voltage rating of the equipment (utilization voltage). Typically the utilization voltage is 3 to 5% lower than the nominal system voltage; for example, a nominal 208 V supply system will be connected to motors with "200 V" on their nameplates. This allows for the voltage drop between equipment and supply. Voltages in this article are the nominal single-phase supply voltages and equipment used on these systems will carry slightly lower nameplate voltages."
 
  #9  
Old 05-15-12, 08:26 PM
Nashkat1's Avatar
Member
Join Date: Mar 2012
Location: USA
Posts: 8,470
Received 1 Vote on 1 Post
Courtesy of Wikipedia
Very interesting. I wonder who actually wrote that? And who last changed it?
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


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