Re: Legally Rquired Standby System
Larry in my opinion no way what so ever and that is how it is enforced here in MA and RI.
701-10 allows article 701 systems to mix with general systems, not emergency systems.
There is also 700-9(b) to consider.
1999 NEC
700-9(b) (b) Wiring. Unless otherwise permitted in (1) through (4), wiring from an emergency source or emergency source distribution overcurrent protection to emergency loads shall be kept entirely independent of all other wiring and equipment. Wiring of two or more emergency circuits supplied from the same source shall be permitted in the same raceway, cable, box, or cabinet.
1. The normal power source wiring shall be permitted to be located in transfer equipment enclosures.
2. In exit or emergency lighting fixtures, wiring supplied from two sources shall be permitted.
3. In a common junction box, attached to exit or emergency lighting fixtures, wiring supplied from two sources shall be permitted.
4. The wiring within a common junction box attached to unit equipment, containing only the branch circuit supplying the unit equipment and the emergency circuit supplied by the unit equipment shall be permitted.
IMO the key part is this
"wiring from an emergency source or emergency source distribution overcurrent protection to emergency loads shall be kept entirely independent of all other wiring and equipment."
This to me says that from the emergency source distribution overcurrent protection (the breaker on the generator) to the utilization equipment has to be separate.
I am sure we have all seen a branch circuit fault open a feeder breaker along with the branch breaker. IMO 700-9(b) is in place to prevent a non-article 700 emergency load from opening any breaker on the emergency system
We install many generators that we order with one, two or three breakers on them, one will feed only true emergency loads fed through dedicated transfer switches and distribution. The other breaker(s) on the generator will feed separate transfer switches for 701 or 702 type loads. The 701 and 702 loads can be mixed but sometimes the engineer keeps them separate as well.
I also think 700-6(d) is very clear
"Transfer equipment shall supply only emergency loads."
Article 701 loads are not NEC 'Emergency Loads'
700-1. Scope
The provisions of this article apply to the electrical safety of the installation, operation, and maintenance of emergency systems....
701-1. Scope
The provisions of this article apply to the electrical safety of the installation, operation, and maintenance of legally required standby systems....