Re: 6 disconnect rule violation?
Wayne
I will attempt to try and explain this to you as best as I can. This would be a lot easier if we were sitting across a table from each other than using a post and read thread so it will take a little understanding on both our parts to achieve this.
Let?s start by looking at the definition of a ?multiwire? circuit.?
Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.
Now a quick look at 210.4 as to the uses allowed for this multiwire circuit.
210.4 Multiwire Branch Circuits.
(A) General. Branch circuits recognized by this article shall be permitted as multiwire circuits. A multiwire circuit shall be permitted to be considered as multiple circuits. All conductors shall originate from the same panelboard or similar distribution equipment.
(B) Devices or Equipment. Where a multiwire branch circuit supplies more than one device or equipment on the same yoke, a means shall be provided to disconnect simultaneously all ungrounded conductors supplying those devices or equipment at the point where the branch circuit originates.
(C) Line-to-Neutral Loads. Multiwire branch circuits shall supply only line-to-neutral loads.
Exception No. 1: A multiwire branch circuit that supplies only one utilization equipment.
Exception No. 2: Where all ungrounded conductors of the multiwire branch circuit are opened simultaneously by the branch-circuit overcurrent device.
In section (A) we are told that a multiwire branch circuit is permitted to be considered as
?multiple circuits? such as a set of three conductors and one neutral supplying lights from a three phase panel. No need for a three phase breaker or handle ties.
Section (B) was changed in the 2005 cycle and the words ?dwelling unit? was removed. Here we are told that if a multiwire circuit hits a device on a single yoke that the overcurrent device must open all poles simultaneously. The use of a handle tie will not achieve this therefore handle ties would not be allowed for this installation. This is also stated in 210.7(B) of the 2005 and 210.7(C) of the 2002
(B) Multiple Branch Circuits. (as mentioned in 210.4(A) ) Where two or more branch circuits supply devices or equipment on the same yoke, a means to simultaneously disconnect the ungrounded conductors supplying those devices shall be provided at the point at which the branch circuits originate.
Note that 210.7 states that if on the same yoke it must open simultaneously which a handle tie will not accomplish.
In 210.4(C) we are told that multiwire circuits are to supply only line to neutral loads but there are two exceptions. #1 is for equipment such as ranges and dryers where there is a neutral and more than one ungrounded (hot) conductor installed.
#2 states that a multiwire circuit that uses line to line loads must open all ungrounded conductors simultaneously and again handle ties will not achieve this, therefore handle ties can not be used.
When we get to 240.20 for the location of the required overcurrent protection we are told once again that handle ties are permitted to be used on line to neutral loads as limited by 210.4(B) This is covered above.
240.20 Ungrounded Conductors.
(A) Overcurrent Device Required. A fuse or an overcurrent trip unit of a circuit breaker shall be connected in series with each ungrounded conductor.
(B) Circuit Breaker as Overcurrent Device. Circuit breakers shall open all ungrounded conductors of the circuit both manually and automatically unless otherwise permitted in 240.20(B)(1), (B)(2), and (B)(3).
(1) Multiwire Branch Circuit. Except where limited by 210.4(B), individual single-pole circuit breakers, with or without identified handle ties, shall be permitted as the protection for each ungrounded conductor of multiwire branch circuits that serve only single-phase line-to-neutral loads.
Notice that 240.20(B)(1) states that handle ties are permitted for use on ?multiwire? circuits. This is again pointed out in 225.33 for the use of single pole units in a remote building.
I think that most if not all of the confusion about the handle ties comes from not understanding the difference between multiwire branch circuits and general purpose branch circuit.
Branch Circuit, General-Purpose. A branch circuit that supplies two or more receptacles or outlets for lighting and appliances.
Branch Circuit, Multiwire. A branch circuit that consists of two or more ungrounded conductors that have a voltage between them, and a grounded conductor that has equal voltage between it and each ungrounded conductor of the circuit and that is connected to the neutral or grounded conductor of the system.
No where in the code am I allowed to install handle ties on general purpose circuits in order to obtain the six disconnect rule of a service 230.71(B) or panel in of a remote building 225.33(B).
