CU vs AL for pottery kiln

[PetrosA]

I recently had a customer who got a new kiln. It's a professional version, 240V 1 phase to be fused at 80A. Her last kiln died, and that producer tried to blame it on the #2 AL feeders to a 100A disconnect in the kiln room (it had #6 CU from the disconnect to the 50A kiln recept). This producer insisted on #4 CU from the panel to the kiln, and kiln is direct wired. Due to this company's being so adamant about insisting on CU, the customer is now questioning whether the AL riser cable that someone from my company put in years ago wasn't the culprit on the one hand, and also wondering if this new company isn't full of it by making her pay for new CU lines. Is there any basis for insisting on CU vs AL in this kind of installation? All cables were properly sized at all times. I explained that properly sized, either cable should work fine and pointed out that our POCO uses AL triplex to feed her AL SEU to the meter, which then feeds AL to the panel.

 

[ozark01]

The installation manual that came with the kiln should have the wiring requirements listed. I bet it only specifies copper at the connection to the kiln. I would show the customer what the manufactures recommends and do it that way.

 

[Cavie]

Over the years I have replaced MANY Al wire connections to Electric heat strips with 50a recps. don't do it.

 

[iMuse97]

The kiln company has a specification for actual hardwiring to their machine? Well fine, if they require CU, install CU, but under no circumstances should a properly sized and installed and torqued AL feeder to the disconnect rated for AL be referenced as the reason the previous one died. They are just not taking responsibility or not willing to tell their customer that kilns die for many and varied reasons.

 

[PetrosA]

Over the years I have replaced MANY Al wire connections to Electric heat strips with 50a recps. don't do it.

The old kiln was corded, and the 50A recept was wired with #6 copper from a disconnect. The aluminum was only run between the main panel and a disconnect in the kiln room.

The kiln company has a specification for actual hardwiring to their machine? Well fine, if they require CU, install CU, but under no circumstances should a properly sized and installed and torqued AL feeder to the disconnect rated for AL be referenced as the reason the previous one died. They are just not taking responsibility or not willing to tell their customer that kilns die for many and varied reasons.

They had a piece of seal-tite from the kiln to hard wire into a JB to the lines that I ran. Their requirement (and what seems so strange to me) is that the customer must install copper from the 80A breaker in the main panel through the disconnect to the JB where their line attaches. They actually went as far as to criticize the fact that we're allowed to use AL in Pennsylvania, and that in "their" state it's not allowed at all. From what the guy who delivered the kiln said, most companies insist on CU the whole way and some will go as far as to void a warranty for using AL feeders. Seems a bit draconian to me... And I can understand why the customer was searching for an explanation - after all, she already had a properly sized feeder installed to the disconnect (the line between disco and kiln had to upsized for the new kiln) but had to pay to have another new line run.

 

[iMuse97]

The old kiln was corded, and the 50A recept was wired with #6 copper from a disconnect. The aluminum was only run between the main panel and a disconnect in the kiln room.



They had a piece of seal-tite from the kiln to hard wire into a JB to the lines that I ran. Their requirement (and what seems so strange to me) is that the customer must install copper from the 80A breaker in the main panel through the disconnect to the JB where their line attaches. They actually went as far as to criticize the fact that we're allowed to use AL in Pennsylvania, and that in "their" state it's not allowed at all. From what the guy who delivered the kiln said, most companies insist on CU the whole way and some will go as far as to void a warranty for using AL feeders. Seems a bit draconian to me... And I can understand why the customer was searching for an explanation - after all, she already had a properly sized feeder installed to the disconnect (the line between disco and kiln had to upsized for the new kiln) but had to pay to have another new line run.

I think they're grasping at straws. Someone they heard once said that AL was bad, etc., etc., all kinds of problems with it.... yada, yada. That being said, I've never installed AL wire inside a building, and it would not be permitted in the areas in which I work.

 

[benaround]

I would have a hard time believing that a manafacturer could legally require any circuit

wiring, except the connection to their equipment, to be of copper or aluminum. The

customer should ask the manafacturer to send her in writing their requirement for this.

I should add that #2 Al. SEU cable is only good for 75amps when used indoors.

 

[PetrosA]

I would have a hard time believing that a manafacturer could legally require any circuit

wiring, except the connection to their equipment, to be of copper or aluminum. The

customer should ask the manafacturer to send her in writing their requirement for this.

I should add that #2 Al. SEU cable is only good for 75amps when used indoors.

I wondered about the legality of it as well. At the time of the SER installation between panel and disconnect, #2 AL SER was accepted by all local AHJs for 100 A indoors and will be until January 1, 2010.

 

[LarryFine]

I should add that #2 Al. SEU cable is only good for 75amps when used indoors.

At the time of the SER installation between panel and disconnect, #2 AL SER was accepted by all local AHJs for 100 A indoors . . .

For a main service and feeder, yes; but for a secondary feeder, the NEC limit was 90a.

 

[PetrosA]

For a main service and feeder, yes; but for a secondary feeder, the NEC limit was 90a.

I'm not arguing that. I'm only stating that local AHJs accepted (and continue to accept - for now...) #2 AL SER for feeding subpanels fused at 100A. As someone mentioned in a thread a few months back, many PA supply houses don't even carry AL SER in in-between sizes and they would be special order items.

 

[LarryFine]

Not a legal excuse, of course, but I personally agree with you, and I believe #2 al will carry 100a just fine in normal temperatures.

I also agree that the aluminum has nothing to do with the kiln failure. A simple voltage-under-load test would confirm that.