Article 424 Disconnect Rating

Status
Not open for further replies.

bphgravity

Senior Member
Location
Florida
1. 424.19

2. New Text

3. 424.19 Disconnecting Means Means shall be provided to disconnect the heater. motor controller(s), and supplementary overcurrent protective device(s) of all fixed electric space-heating equipment from all ungrounded conductors. Where heating equipment is supplied by more than one source, the disconnecting means shall be grouped and marked. The disconnecting means specified in 429.19(A) and 424.19(B) shall have an ampere rating not less than 115 percent of the total load of the motors and the heaters.

4. There is no specification in Article 424.19 on the rating of the disconnecting means. Based on this, one could install a 30-ampere rated disconnect on a 60-ampere branch circuit and still be in compliance with the code. This new requirement would be consistant with disconnect ratings in other articles such as motors and air conditioning and refrigeration equipment.
 

George Stolz

Moderator
Staff member
Location
Windsor, CO NEC: 2017
Occupation
Service Manager
Re: Article 424 Disconnect Rating

If a disco is only rated for 30 amps, it would violate listing to install it on a circuit where it would interrupt more than 30.

Right? :D
 

bphgravity

Senior Member
Location
Florida
Re: Article 424 Disconnect Rating

This is true, however, why do motor and A/C equipment disconnects need to be sized at 115% of the load and yet other similiar appliances like heating equipment do not?
 

rbalex

Moderator
Staff member
Re: Article 424 Disconnect Rating

Specificity is generally a good thing and motor sustained inrush (especially for fans) make this an appropriate Proposal at least "in principal."

For Manual of Style purposes you may want to propose the requirements to be in the specific appropriate sub-sections rather than the "basic" rule. Otherwise, it gives the CMP a basis to reject if they feel it's too general or if accepted may cause unintended consequences, such as requiring it for heaters that have no motors at all.

Another possible option is to refer back to Art 430.

You may want to correct your reference to 429.19(A). ;)

Nevertheless, IMO this is an appropriate Proposal on its face. Right now, technical merit is not the primary goal of this forum. We want to help folks make Proposals that will not be rejected outright without due review. Technical merit is the goal of the Comment stage.

[ March 08, 2005, 10:32 AM: Message edited by: rbalex ]
 
Status
Not open for further replies.
Top