Manufacture violating NEC

[hurk27]

40A @ 80% = 32A

Sidenote: something funky going on here... prior to adding this line, I kept entering "A" for amperes and the board kept changing it to "a"... until I added more text

Sounds like the old caps lock gremlin

 

[LarryFine]

Sidenote: something funky going on here... prior to adding this line, I kept entering "A" for amperes and the board kept changing it to "a"... until I added more text

10-character post minimum.

 

[mivey]

10-character post minimum.

40A @ 80% = 32A
has 15 characters

 

[iwire]

the nec allows a 40 amp breaker to carry 37 amps for up to 3 hours at a time. There is no way that unit will ever draw 37 amps for more than 3 hours continuously

40A @ 80% = 32A

Yes, thanks for pointing out what I already knew. :grin:

Can you now tell me why your pointing it out?

Hillbilly's load was actually 37.5 but I was simply pointing out the 40 amp breaker could carry 40 amps (exceeding his 37.5 amp load) for 3 hours or less.

 

[pfalcon]

NEC vs MFG

NEC vs MFG

I dunno, I'm with pfalcon on this one. The NEC has to address such a grand range of issues that it's requirements and recommendations can't help but contain inaccuracies. The mfg. requirement may look lower numerically, but they may provide the more stringent protection.

I like supporting those who support me :grin:

Remember that the NEC is addressing things like receptacles. No one really knows what will be plugged in and therefore: Beef up the wires and breakers.

The MFG knows by testing what his load and usage are going to be. Therefore they don't have to add the extra beef. And since smaller is typically cheaper they have incentive not to over-protect.

 

[LJSMITH1]

Are you new to this biz? :grin:

This is so not true based on some of the stuff I've installed through the years.

Are you talking about not being able to find someone at a Mfr that knows what they are talking about? Or are you talking about the questionable performance of a product?

I am new to the sector of product that I am involved with, but not new to manufacturing, certifications, testing, or listing. If you guys think the NEC is an interesting read...you should try MIL-SPECS... That would certainly put you over the edge...

 

[Smart $]

Yes, thanks for pointing out what I already knew. :grin:

Just didn't want to give a newbie the impression they could put a continuous load of 37A on a 40A breaker... that's all.

Can you now tell me why your pointing it out?

You already managed to answer for me ...

Hillbilly's load was actually 37.5 but I was simply pointing out the 40 amp breaker could carry 40 amps (exceeding his 37.5 amp load) for 3 hours or less.

 

[wasasparky]

As a side note, the manufacture did not print the 40 amp as being the "Max size brkr", so #6 and a 50 amp would be legal.

???

I thought they said 40A? (Not offering a max limit as with an A/C condenser...)

...manufacture calls for 40 amp ocp...

Now a 50 is OK?

... or do I violate the manufactures instructions with a 50 amp breaker?

 

[electricmanscott]

Are you talking about not being able to find someone at a Mfr that knows what they are talking about? Or are you talking about the questionable performance of a product?

Yes.

 

[KentAT]

Hooking up a new double oven today at one of our sales guys house, the exsisting wiring was #10, the new oven is a 9kw, manufacture calls for 40 amp ocp. With this being a 37.5 amp load, a 40 amp breaker and circuit will not meet NEC minimum breaker size. Do I violate the NEC with a 40 amp breaker? or do I violate the manufactures instructions with a 50 amp breaker?

My take on this (just trying to work it out - not saying this is correct...)

Based on 2008 NEC:
Appliances:
422.10(A) "...Branch circuits and branch-circuit conductors for household ranges and cooking appliances shall be permitted to be in accordance with Table 220.55 and shall be sized in accordance with 210.19(A)(3)."

Table 220.55, Column C for 1 appliance (I'm assuming, since you have 1 nameplate and your are under 12KW), permits the branch circuit to be sized for a maximum 8KW demand.

This equals 33.3A at 240V, so your branch-circuit is rated at 33.3A. The conductor size is based on this, and the OCP is based on the conductor size.

8AWG and 40A seems appropriate.

Sound good?

kent

 

[slick 50]

[/QUOTE]

My take on this (just trying to work it out - not saying this is correct...)

Based on 2008 NEC:
Appliances:
422.10(A) "...Branch circuits and branch-circuit conductors for household ranges and cooking appliances shall be permitted to be in accordance with Table 220.55 and shall be sized in accordance with 210.19(A)(3)."

Table 220.55, Column C for 1 appliance (I'm assuming, since you have 1 nameplate and your are under 12KW), permits the branch circuit to be sized for a maximum 8KW demand.

This equals 33.3A at 240V, so your branch-circuit is rated at 33.3A. The conductor size is based on this, and the OCP is based on the conductor size.

8AWG and 40A seems appropriate.

Sound good?
kent

Yes

 

[Power Tech]

The NEC allows a 40 amp breaker to carry 37 amps for up to 3 hours at a time. There is no way that unit will ever draw 37 amps for more than 3 hours continuously[/QUOTE]

Longer than that if you use Murray.

 

[LarryFine]

Longer than that if you use Murray.

But, for the ultimate in long-term overcurrent capacity, nothing beats Federal Pacific.