wire ampacities 310.16 90degree c chart

[weressl]

If the labeling only indicates a max fuse size the EC must provide a fuse in line regardless of fusses that may or may not be in the unit.

From the IAEI Magazine

http://www.iaei.org/magazine/?p=3944

A magazine is hardly an authorative statement.

A 'fuse' instruction is insufficient since if there is no fuse type or specific operating characteristics provided, which is most of the cases. Some ASD manufacturers lists the specific fuse that must be provided.

 

[gndrod]

Thanks Bob,
The IAEI was a superb read. Now I know when running energy management LV controls, why some of the roof HVAC were fused and others were not. rbj

 

[iwire]

That was my point. There are cables that do not match the NEC criteria or not listed in the NEC, yet UL approved.

What cables do you have in mind?

If they are not listed in the NEC I can not use them for NEC applications.

I disagree. The Code requires overload protection. It oversteps its authority when tries to enforce other requirements. That is between the AHJ, the User and the listing Authority. There is case law precedent for that.

IMO your mistaken, in this case the AHJ would only be asking for what the labling requires, not 'other requiments.

A magazine is hardly an authoritative statement.

I agree, one single source is not very authoritative. But believe it or not this is common trade knowledge and even if you do not agree with it ....... it is a fact and how the NEC is applied.

A 'fuse' instruction is insufficient since if there is no fuse type or specific operating characteristics provided,

I truly understand what your pointing out and I agree that a simple 'fuse instruction' is very vague and that there are many fuse types out there.

Regardless, if the unit only says 'max fuse size' we must have a fuse of some type in the circuit supplying the unit.

Here is another source, the NFPA themselves with a UL standard attached.

http://www.necplus.org/Features/Pages/HVAC_SCCR.aspx?sso=0

Is a specific type of overcurrent protective device required?

According to UL 1995, 36.3(i), the HVAC nameplate can specify the type of overcurrent protective device that must be used. If the nameplate specifies ?Maximum overcurrent protective device,? then either a circuit breaker or fuse is permitted. If the nameplate is marked ?MAX. FUSE_____,? fuse protection must be provided in accordance with the label. If the nameplate is marked ?MAX. CKT. BKR_____,? a circuit breaker must be provided in accordance with the label.