Electrical-Educational Moment

Here is a question that may puzzle you…the intent is to learn WHY and not to make you Electricians…BUT more so to understand when you are looking in a panel and seeing the label saying one thing…but observing the OTHER.

Plus it is just plain fun and Im bored…

Question: Can a 9.8A 120V central vacuum system, which is fastened in place, be supplied by an existing 15A, 120V, Single Phase receptacle circuit?

If you know explain yes or no…and if you don’t…TRY anyway…!

I will then explain the reason for the question…

Edited: For Clarity ( Thanks Greg…:slight_smile:

If the receptacle circuit has no other outlets I don’t see a problem.
It gets a little shaky when this is a duplex and something else, not fastened in place, gets plugged in.
210.23(A)(2) Utilization Equipment Fastened in Place. The total rating of utilization equipment fastened in place, other than luminaires (lighting fixtures), shall not exceed 50 percent of the branch-circuit ampere rating where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.

If there is another “fastened in place” piece of equipment present, the 80% rule kicks in.
Generally I see a single receptacle in an individual circuit installed next to the central vac unit.

You are good my man…Actually the FASTENED IN PLACE takes command of that requirement…so 50% is it…so with that said…9.8A is more than 50% of the 15 A rating…

Now funny thing is…UL and testing labs list portable equipment at 100% of the circuit rating…but other than fixed in place allowances the NEC strives for 80% as greg stated…and the NEC uses 80% alot…lol…

As far as in the NEC’s eyes…it would not be allowed because of the cord from the central vac going to it and the central vac being fixed…it requires a circuit that supplies its 9.8A at a 50% level for the branch circuit…

15A would only allow 7.5A…While 20A would provide 10A…

Hope that was educational for everyone…the funny thing is…like greg said…it would probably work fine either way…lol

Not quite that easy, the 2d paragraph also applies.
“where lighting units, cord-and-plug-connected utilization equipment not fastened in place, or both, are also supplied.”

So if there is nothing else connected (generally enforced by the single receptacle) you can go to 80% and a 15a is OK.
In a practical sense there isn’t enough difference in price between a 15 and a 20 to justify exploiting this so I usually see a dedicated 20 with a NEMA 5-20 receptacle. Since these end up in the garage the single behind the vacuum unit also avoids the need of a GFCI.
The garage GFCI outlet is usually installed with the TUG as the only breaker in the panel for the construction folks so we don’t have that problem.

lol…Dont add the single receptacle fella…lol…I should have stated it was a standard duplex receptacle…lol

Actually my understanding of it Greg …the fact it is a “Utilization Equipment Fastened In Place” it can’t simply be on the same 15A circuit as a stardard receptacle circuit is…what I was kinda trying to get at…lol

So I think in the example it would have been BETTER for me to list it was a standard duplex receptacle…not didicated…allowing other items to potentially be plugged into the same outlet…

Man thats why I lOVE this stuff…I guess I assumed unless I stated dedicated it was a standard 15A receptacle circuit…hey bud…I am learning the right way to post things…lol…harder than in a class room…:slight_smile: