I have a couple questions, both about one circuit. There ia a GFCI outlet in the garage the protects outlets in the garage (3 outlets), exterior (2 outlets), all three bathroom outlets and about 6 outlets in the finished basement. I am thinking this is too many outlets for the circuit and should a single GFCI cover all these areas in a home? I thinking there should be a separate circuit for the basement outlets. House was built in 1999. I could not find the breaker for this circuit, not labeled, so I don’t know the size of the breaker covering this circuit. I probably wouldn’t of thought much of it except I kept having to go back in the garage after tripping all the outlets.
I don’t think there is a limit, but the length of the wiring may cause nuisance tripping on the GFCI.
Thanks for the reply Marcel. Forgive my ignorance but how does the length of the circuit effect the GFCI? Does it have to do with voltage drop? Also if the load is too much what will trip first, the GFCI outlet or the circuit breaker?
I’m probably not much better David, no apology required.
Length of circuit. A GFCI is subjected to tests that simulate long branch circuits. While there are no specific rules concerning the length of the circuit protected or the number of receptacles on the protected circuit, remember that the GFCI will add up all the harmless leakage currents and capacitive leakages. Under extreme circumstances, this could “preload” the GFCI and make it appear overly sensitive or, worst case, result in nuisance tripping. Therefore, you should minimize the length of circuits to the degree possible.
Hope that helps.
The bathrooms should have their own circuit. I think the limit is 10 outlets?
It depends on the code cycle under which the receptacles were installed. Under the 1993 NEC the bathroom receptacles could be on with other outlets. Under the 1996 NEC the bathroom receptacle(s) required their own 20 amp circuit.
There is no 10 outlet limit for residential installations in the NEC.
Also the number of receptacles does not add any load. The load is determined by what is in use.
Yes, but the more receptacles the circuit has, the chance of overloading is increased?
Yes, the chance of overload is possible, but there is no way to know what will be used, especially in a residential setting. The loads are transient in nature. I could overload a circuit with only one duplex on it.
While your house sounds like it met the codes of the era, it would not meet later more stringent codes.
As other pointed out, during the era of construction I don’t think there were any “issues” with the amount of outlets present. If it were my client I would make them aware of the current condition and that due to the amount of outlets on the circuit and the locations of the outlets on the circuit that tripping the GFCI and/or breaker might become an annoyance. There could be hair dryers, dehumidifies & who knows what in the garage that could causing tripping of the components to be a regular occurrence.
Does your city, county, or state have an absolute limit or use a wattage schedule? If so, that will determine the maximum number of devices on any circuit. Otherwise, the rule of thumb is 180VA for each yoke or strap. That works out to 10 receptacles on a 15A circuit and 13 on a 20A circuit.
Yes, based on the 180VA rule, the limit is 10 on a 15A circuit. However, local codes often deviate from the general rule.
It is also worth noting that for residential electrical system design, a Watt and a Volt-Ampere are generally regarded as being equal. The reason is that the ratio of resistive loads to inductive loads in residences is typically much greater than in commercial and industrial electrical systems. The term VA is preferred over Watt for consistency.
Electrical systems are designed based on demand loads, not actual loads. Demand loads are determined statistically using more than 100 years of collected usage data. Demand load calculations include a comfortable margin for error.
The person who said the design criterion is arbitrary obviously knows little about the electrical industry. In all my years in the electrical field, I have never known of any design criteria to be arbitrary.
The person who made the “diversity” statement is correct. Diversity is a term that is synonymous with Demand.
Just trying to figure out who is right here. There always seems to be a different answer on every question asked.
The NEC does not require the use of 180va per receptacle in residential. Like Jim stated you could overload a 15 amp circuit with one duplex on the circuit.
I am still on this 180 va rule thingy here.
Commercial/industrial vs. residential
You’ve probably noticed that receptacle calculations for commercial/industrial applications differ from those that apply to residential applications. The differences exist because in residential locations, the receptacles are generally placed much closer together for convenience purposes but used in a diverse manner — so that all receptacles are not heavily loaded during all periods of time. In commercial occupancies, there are fewer rules governing receptacle placement, so they may be placed as needed, but may be called into use more often and for longer periods of time. In dwelling units, the receptacle load is included in the general lighting load VA calculated according to Table 220.12 and is then subject to the demand factors of Table 220.42. The 180VA per receptacle strap allowance does not apply to dwelling unit calculations.
So, are they wrong too?
Like Robert says, this does not apply to residential.
The 180va per commercial receptacle is used for sizing the service. In residential it is covered by the 3va per square foot.