Probably a dumb question but....

[Highbeam]

I am wiring in plugs for the shop. 20 amp circuit, 120 volt, 12 gauge wire, first outlet is a GFCI and then each "downstream" outlet is normal 15 amp with pigtails to the outlet. I put in the first 8 downstream outlets last night and got to wondering, is there a limit to how many outlets I can have on one circuit?

I plan a second 20 amp outlet circuit for the opposite side of the shop and of course my lighting is on its own circuits.

Since I have your attention, I plan two 30 amp 120 volt outlets for my RV. Sometimes I park it in different places. Can I have more than one 30 amp outlet on a circuit?

I really like wiring and all will be inspected in the end.

For your trouble, a glass of homebrew red ale. Thanks!

 

[pattenp]

There is no limit on the number of outlets by code.

 

[Norcal]

There is no limit on the number of outlets by code.

Only in residential.

 

[Highbeam]

I'm sorry, this garage is a residential structure. A detached garage with a subpanel.

 

[Aceman]

You won't hit the recep limit anyhow if your only doing 6-8 per circuit. You don't want a ton after a GFCI anyhow, unless you want the potential for nuisance tripping.

I also don't see a problem with multiple RV receps on the same circuit either.

 

[pattenp]

Only in residential.

Yeah, I assumed is was residential.

 

[Highbeam]

Thanks folks. I'll end up with probably 15 receptacles on this circuit downstream of the GFCI and no, I don't want nuisance tripping but I've never experienced it either. What is the normal nuisance tripping guideline?

 

[Aceman]

Thanks folks. I'll end up with probably 15 receptacles on this circuit downstream of the GFCI and no, I don't want nuisance tripping but I've never experienced it either. What is the normal nuisance tripping guideline?

I believe it's around 6-8 receps/devices.

 

[pattenp]

See nuisance tripping in this article...

http://safeelectricity.org/index.ph...y/317-ground-fault-circuit-interrupters-gfcis

 

[Highbeam]

That article states:


To avoid nuisance tripping, a GFCI should not supply:
Circuits longer than 100 feet
Fluorescent or other types of electric-discharge lighting fixtures
Permanently installed electric motors

But nothing about number of downstream devices. Also, does it matter that I pigtailed each outlet so that no current must pass through each outlet to the next?

I'm actually considering a new circuit to avoid exceeding 8 devices as recommended by Aceman.

I also did not use tamper resistant plugs since this is not a "dwelling". Is that okay?

 

[aandpdan]

I also did not use tamper resistant plugs since this is not a "dwelling". Is that okay?

Check with your AHJ. But they're required by Code - if the building is consider an "accessory structure."

NEC 406.12 requires them where specified in 210.52 and detached garages with electric are under 210.52(g).

So, put them in.

There are always exceptions. You don't need them over 5 1/2 feet for example. 406.12(1)

 

[ishiboo]

Sorry, I didn't read the whole post.

 

[p912s]

Curious about the receptacles you're using. Why are you using 15 amp receptacles on a 20 amp breaker? Why not use 20 amp receptacles?

Thanks

 

[Charles (in GA)]

Curious about the receptacles you're using. Why are you using 15 amp receptacles on a 20 amp breaker? Why not use 20 amp receptacles?

Thanks

Because NEC says that if you have more than one receptacle on a 20a 120v circuit, then you can use 15 amp rated receptacles. A DUPLEX receptacle is considered TWO receptacles according to the code.

Fact is, commercial or industrial quality 15a receptacles are the same inside as the 20a ones, the only difference being the face plate and the approvals. I've never seen a piece of equipment with a NEMA 5-20 plug on it, so having 20a rated NEMA 5-20 receptacles is rather a waste in a typical home shop. I suppose you might find floor buffers and things like that that use them, possibly a MIG welder, but I've never seen one.

Charles

 

[Charles (in GA)]

Thanks folks. I'll end up with probably 15 receptacles on this circuit downstream of the GFCI and no, I don't want nuisance tripping but I've never experienced it either. What is the normal nuisance tripping guideline?

The portion of the code that covers commercial buildings restricts the number of receptacles by requiring calculations to be done at 180va per strap, this equates to 13 receptacles max on a 20 amp circuit. You could use this as a guide line for your shop, but it is NOT a requirement.

Charles

 

[Highbeam]

Correct that I don't need or want to pay for the 20 amp receptacles. I have never ran into equipment that required that goofy sideways prong.

I like using that commercial guideline Charles. Is the 13 receptacle max mean 13 duplex outlets or as you point out earlier am I limited to 6.5 duplex outlets?

 

[Charles (in GA)]

13 straps or yokes. If the single outlet strap or yoke has FOUR or more receptacles on it, you use 90va per receptacle to do the calculation.

20 amp breaker times 120 volt equals 2400 divided by 180va equals 13.33 straps or yokes per circuit. 2400 divided by 90 va equals 26.66 individual receptacles per circuit.

Here is an example of the "four or more receptacles per outlet" to be calculated at 90va per receptacle.

Here is a triple receptacle, which like its single and duplex brethern, would be calculated at 180va per yoke/strap.

Remember, this is all based on Commercial installations. There is nothing in the code relating to residential that is similar to this.

Personal opinion, 13 receptacles on a circuit is way too many, but its your choice (and future problems).

Charles

 

[Highbeam]

Thanks again Charles. With a little bit of extra wiring and another GFCI outlet I can limit the downstream protected devices to 5 per GFCI which should greatly reduce the likelihood of nuisance trips.