208 Vs 220

[gsrandy]

I recently had an elctrical inspector tell me and if fact rejected an installation where a coffe brewer rated 220 volt on a 2 pole 30 amp circuit installed where only 208 was available. He said the NEC would not allow a 220 volt rated piece of equipment to be wired to A 208 VOLT CIRCUIT.Can anyone tell me where he got this?

 

[bphgravity]

Re: 208 Vs 220

You've got 110.3(B) working against you. Unless the equipment has a dual voltage rating, I would have to agree with the inspector.

On a side note, it is interesting that 110.4 does not exactly apply to this situation which is exactly opposite of the specific rule. Perhaps this rule should also include this issue as well.

 

[petersonra]

Re: 208 Vs 220

You may find that you are actually ok. usually, the instructions that come with such a piece of equipment will specify the voltage range allowed. If the instructions were to say 230V +/- 10 %, you would be OK at 208V, even with his rigid interpretation of the rule.

I have seen heating appliances (which is what a coffee pot is) not even list a lower range. Just a maximum voltage.

[ June 10, 2005, 03:31 PM: Message edited by: petersonra ]

 

[infinity]

Re: 208 Vs 220

I'm surprised that he wouldn't allow it since the coffee will just take longer to brew seeing that the element will produce less heat at 208 volts. I could see there being a problem if it were the other way around since the higher voltage could possibly damage the heating element.

 

[mc5w]

Re: 208 Vs 220

208 volts produces 3/4 as much electric heat as 240 volts. Most commercial 240 volt cooking equipment with electric heaters have the heaters sized to tolerate the lower voltage. The thermostat just simply cycles ( throttles ) the heating element less.

There is also a NEMA standard somewhere that allows 240 volt single phase receptacles to be supplied with 208 volts.

The worst thing that can ahppen is that a 240 volt motor on a 208 volt circuit will nuisance trip its overload relay. If it fails to start on 208 volts there is not enough starting torque on 240 volts to accelerate the load in a reasonable amount of time - the motor is either too small or some type of mechanical unloading needs to be done which is common with air compressors.