Electrical question.

NDallyn

NDallyn

Joined
Jun 22, 2006
Messages
814
I'm looking at purchasing an "in-stock" 22.5" Evenheat oven for a better price than I can get by ordering direct. The plug supplied with the oven is a NEMA 6-20R (20 amp). The problem is that my power supply is a NEMA 6-50R (50 amp). Can I just make a jumper (female 6-20 on one end to a male 6-50 on the other) to plug the oven in? Or is this going to fry my oven? Pics of plugs are here:
http://www.evenheat-kiln.com/technical/recept/recept.htm

If I can avoid calling in an electrician and inspector to put in new wiring and receptacles, it would save me a lot of hassle and money.

Thanks a lot,

Nathan
 
I have no experience with evenheat ovens, but if it comes factory wired with a 20 amp plug then you should have no problem making a jumper to go to a 50 amp plug. If the oven is factory wired with a 20 amp plug then all it should ever draw is 20 amps.

I think a better solution would be to cut the 20 amp plug off the end of the oven cord and just wire the 50 amp male plug right to the end of the oven cord. The more connections you have in the supply line, the more chance there is for voltage drops across the circuit.

Hope that helps ya out.

Tek
 
The oven comes with a 20 amp plug and the controller has a 15amp fuse to the power supply. My electrical experience is fairly limited (wiring in welders and extensions). Just wanting to make sure that tying into a higher amperage circuit wasn't going to fry the controller (which would make me very unhappy).

Thanks,
Nathan
 
NDallyn,

I have practically the same oven except in 27 inch model. You can do what you are saying, however, since the 6-50R is rated for 50 amps and your kiln or our kilns are only rated for 20 or 15 amps, if there is a sudden voltage spike lord knows why in the plug, your kiln will be fried and most likely a fire will start. My suggestion is that you can make a plug from NEMA 6-20R to NEMA 6-50P, but you must change the receptable fuse to 20 amps....that way, if too much power goes through, you don't damage your kiln and cause your house to burn down. If you don't change the fuse going to the 6-50 receptable, it will not trip as it's rated for 50 amps and surely something will get major messed up.

If you are gutsy then sure you can just make an extension cord direct from the kiln to the wall and risk it. Not my advice though. That thing cost a whole bunch of money just to go up in smoke! You can actually buy an extension cord with the NEMA 6-20R already on it from LOWES hardware store (where I got mine) and just cut off the plug other end and wire it into a 6-50 plug.

It will cost several and i do mean several hundred bucks for an electrician to wire that for you if you wanted a free standing line. I think a few years back i paid $950.00 bucks for the 27 inch model which I believe was 10% off the retail price from Tim Zowada. www.tzknives.com Tim is a distributor for Evenheat kilns and also a master bladesmith as well.

Best Regards,

Pohan Leu
 
Has anyone ever plugged a 5 amp coffee maker into a 15 amp wall plug? Did it burn your house down? How about the welder you plug into that 50 amp circuit. Does it draw 50 amps? The breaker in the panel is to protect the house wiring - and presumably the 50 amp outlet you have has been wired with the proper guage wire.

The controller itself is protected by a 15 amp fuse, so anything more than 15 drawn by the kiln is going to fry that quickly.

My concerns would be with respect to an insurance adjusters reaction to a home made extension cord - and possibly Evenheat's reaction to a cut off and replaced plug. To be clear, if they are done well, I don't see either of those as safety concerns - just liability concerns.

My 2 cents

Rob!
 
The plug it self has no current limiting ability other than heating up and burning up. If you were to place a 20 amp plug on a device that drew 50 amps, the device wold start up and work until the plug either fried or welded itself together. If you had a 20 amp plug on the device and a big spike hit the 20 amp plug wouldn't even slow it down. The rating for plug is how many amps they can continuously carry over a long period and as with all things they are under rated. A 20 amp plug will carry 25-30 amps for over a day if in decent condition.

I would personally make the adapter or intal a new plug on the device. Actually I would install a new breaker in my shops box and runn another wire and plug
 
Rob, the cord on your 5 amp coffee maker is rated to handle the full 15 (or 20 actually) amps, even though it only draws 5, so if you ever cut it, causing a short circuit, the breaker will still trip.

The cord rated for 20 amps becomes the fuse when plugged into a 50 amp outlet, and therefore it will melt/burn/vaporize long before the 50 amp breaker trips.

There are several ways to go with this problem. You can change the breaker and outlet to 20 amp units, and this should be relatively easy to do yourself. It is perfectly permissible to use the larger wire from the 50 amp circuit with a 20 amp breaker, just not the other way around! Secondly (and more expensively) you could install a small circuit breaker panel at the 50 amp outlet (most municipal codes allow this, but you may have to get a permit) and branch out with several 20 amp outlets. Finally you could rig something with a cord rated for 50 amps to a fuse box (we do crap like this all the time...it is ugly but safe) and fuse it down to 20 amps, and go from there.

The bottom line is that the 50 amp circuit breaker is your safety device and putting a 20 amp cord downstream of it (without auxiliary short circuit protection) is asking for trouble.

Just one electrical guy's take on your situation...be safe!
 
CDH said:
The bottom line is that the 50 amp circuit breaker is your safety device and putting a 20 amp cord downstream of it (without auxiliary short circuit protection) is asking for trouble.
Click to expand...

That's not the case......he's already said that the controller has a 15A fuse so the power supply cannot draw 50A through the 20A cord/plug.......not for long. :rolleyes:

Put a 50A plug on the cord and be done with it or get a 4-square box, mount a 20A recepticle and make your pigtail with a 50A plug.....;)
 
Yes it is, for the length of cord between the plug and the controller. That is my concern...if you accidentally cut or crush the cord itself, the wire in the cord will melt or vaporize in milliseconds. The controller may be protected, but the cord is undersized and therefore it is the weak link.
 
The moral of the story is, don't cut the plug off your evenheat kiln that it came with (because you might want to sell it someday) and do it right. It only takes 1 mistake and you're out a grand or maybe a house or building! Be safe and ask some electricians, i'm sure there are some out there willing to give advice for free. A cheap way to do something in the end can cause you alot of $$$$$.
 
Leu Custom said:
Be safe and ask some electricians, i'm sure there are some out there willing to give advice for free.
Click to expand...

One (sorta) is right here. I am an Electrical Engineer, I supervise a department of EE's doing design work for industrial power and control systems, and run roughshod :D over electrical contractors...
 
Nathan, I have been running my Evenheat for years using an adapter with a 20A female 220 to 50 amp male to match my 220 outlets. There is aboslutely zero problem with that.

Perhaps if one couldn't figure out how to wire the neutral to the correct prong at either end, then maybe they need an electrician. Other than that, it should not be any big thing. Use heavy 10 gauge "contractor"-grade cord and industrial quality plugs and it will never be a weak link in the system.
 
Obviously you can do what you want, but there is a good reason the National Electrical code allows a maximum of 30 amp breakers feeding wire of 10AWG. For a 50 amp circuit 6 AWG wire is required to insure that the breaker trips before the wire melts. (2005 NEC, 60 degree max wire types TW and UF, typical of that found in a household installation). Keep in mind that the function of a circuit breaker is NOT to protect the item plugged into the power system, it is to protect the wiring. That's right, the breaker size is matched to the wire size, nothing more and nothing less. That is why a fuse is required in virtually any power consuming device that plugs into an outlet.

I know for a fact that 10 AWG wire will get hot enough to blister your fingers on contact without tripping a 50 amp breaker when I did it diagnosing a poor installation of a hot tub. Since breakers are made with a time delay response so they don't trip out during the starting of a motor, they can actually run a 100% overload for several minutes before tripping.

The cord on your Evenheat oven is probably 12-14 AWG to boot...even smaller, and THAT is the weak link. During normal operation there will be no problems, but the first time you drop something heavy or sharp on the cord and cut through the insulation, you will melt the cord or worse.

The bottom line is that in doing this you are removing a part of your safety net. It is your house...
 
Thanks to everyone for their advice. I actually know a couple electricians. Both of them said that making a jumper or putting a new cord on the end would work - but - added the disclaimer that they've never worked with a kiln before, which is why I asked here.

CDH - it seems like tradesmen (the guys with the practical experience) and engineers/techs (theoretical/design experience) always find something to disagree about. I'm a journeyman welder - have seen my share of designs that were impossible to fabricate (a 3" and 4" sch.80 pipe in a 6" hole?). If it's any consolation to you, this oven will be going on a bench in a shop - not in a house, not on the floor where the cord could be crushed. In either case, couldn't I just wire in a 20amp breaker between the 20 and 50 amp plugs?

This shop is going to have a new panel installed sometime in the next year or so - I was looking for something that would work temporarily in the single 220v outlet (50 amp) in the shop until the new panel is installed (try finding an electrician in Alberta that isn't booked for 3-4 months solid).

Thanks a lot,
Nathan
 
NDallyn said:
CDH - it seems like tradesmen (the guys with the practical experience) and engineers/techs (theoretical/design experience) always find something to disagree about. I'm a journeyman welder - have seen my share of designs that were impossible to fabricate (a 3" and 4" sch.80 pipe in a 6" hole?). If it's any consolation to you, this oven will be going on a bench in a shop - not in a house, not on the floor where the cord could be crushed. In either case, couldn't I just wire in a 20amp breaker between the 20 and 50 amp plugs?

This shop is going to have a new panel installed sometime in the next year or so - I was looking for something that would work temporarily in the single 220v outlet (50 amp) in the shop until the new panel is installed (try finding an electrician in Alberta that isn't booked for 3-4 months solid).

Thanks a lot,
Nathan
Click to expand...

Engineers and tradesmen disagreeing? Surely you jest! :D Actually I worked with my hands for many years before finishing a degree at near 30 years old, so I have been at both ends of it.

The best temp fix is replacing the outlet and the breaker feeding it with 20 amp versions. It is quick, relatively cheap, reversible, and safe. You will find that adding a breaker after the plug is difficult without a box to mount it in (the second idea in my first post on the thread) which adds cost and complexity.

In your experience as a journeyman welder, I'm also sure you have seen your share of trade tricks that are, shall we say, questionable? Without knowing the experience level of the end user, I will ALWAYS err on the side of caution...

Good luck and be safe!
 
CDH said:
Engineers and tradesmen disagreeing? Surely you jest! :D Actually I worked with my hands for many years before finishing a degree at near 30 years old, so I have been at both ends of it.

The best temp fix is replacing the outlet and the breaker feeding it with 20 amp versions. It is quick, relatively cheap, reversible, and safe. You will find that adding a breaker after the plug is difficult without a box to mount it in (the second idea in my first post on the thread) which adds cost and complexity.

In your experience as a journeyman welder, I'm also sure you have seen your share of trade tricks that are, shall we say, questionable? Without knowing the experience level of the end user, I will ALWAYS err on the side of caution...

Good luck and be safe!
Click to expand...

The problem is that the outlet is also used to power a welder. I have some "connections" with a certain industrial maintenance company in town - I could probably get a used breaker box for free or a new one for a discounted price. To me, a hundred bucks or so in parts is worth it to have things running properly.

As for welders, it's amazing how much work some guys will do to avoid having to grind out a weld. Laziness is all it is, and most of the time it takes longer to hide something than it does to fix it properly. If you ever see a welder with a tube of silicone, or a spray-bomb can of primer (or anything besides a stinger, hammer, chisel, wire brush and grinder) start looking at things very closely.

Nathan
 
Those are some mighty beautiful knives you make there NDallyn! What kind of etching machine/device do you use to put your mark on with?
 
I'm also using a Mark 440 stencil maker from martronics. That little etch-o-matic works very well for the price, but I have had some issues with fuzzy marks (over-etching). Since you cannot set any values for voltage and amperage, you have to expirement to find the right etch time for the steel and stencil you're using. Plus, the size of the marker and pad makes it easy to touch parts of the blade outside of the stencil (have to be aware of how you position it). Overall though, it is a very quick and efficient little machine.
 
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