wrote:

On Thu, 31 Oct 2013 16:15:30 -0700 (PDT), Pavel314
wrote:

On Thursday, October 31, 2013 3:49:22 PM UTC-4, wrote:
On Thu, 31 Oct 2013 08:36:12 -0700 (PDT), Pavel314

wrote:



Our greenhouse heater wore out after a number of years so we bought a replacement. It's essentially the same heater except that the new one is a different color and the plug is a different configuration. The old one has one round pin and two flat blades, with the blades at an angle to each other and above the round pin. The new one also has one round pin and two flat blades but the blades are lined up with each other, so I have to replace the receptacle with one that matches the new plug. Not a major project, just a minor annoyance and expense.



I've seen other 220 volt plug configurations; some have an L-shaped blade instead of the round pin, others have four blades in a circular pattern which lock when turned, etc. Is there any practical reason for all these variations?



Paul



Are you sure the old heater was 240v?

The plug you describe is a 30a 120v plug.



The new heater would "work" on 120v but at about 1/4th the output.

Yes, it was a 240v. On the link

http://www.mikrocontroller.net/attac...eceptacles.gif

the original plug is in row 7, 20R, while the new one is in row 6, 30R. The new heater is rated at 30 amps.

Thanks to all for their comments and links.

Paul

That 7-20R is for 277v, (the L/N of 480v wye).

Again it would work on 240v but at lower power.

If the original was 277V and they connect a 240V rated heater to it, the
heater will run at higher power and may overheat.