photocell sizing

[mavrck]

I have a question about a photocell. I have a 5 amp load on a LED sign. I'm using a 6 amp led rated photocell to switch it. My question is can you use a 6 amp rated photocell on a 20 amp circuit? From what i can see by code a commercial sign has to be on a dedicated 20 amp circuit. I cant find a code reference talking about this application.

 

[hbiss]

You would go by your load, in this case 5A. So a 6A rated photocontrol might be a little too close for comfort for me, but it should work. Your only other option is a larger one if you can find it or a photocontrol operating a contactor.

-Hal

 

[mavrck]

Ok , how does code classify photocells by controls? Reason i ask snap switches have to be rated for 20 amp if on 20 amp breaker. Why doe s photcell not need to be. What size photocell would you go with and why. Thx

 

[mavrck]

I guess the actual question i should be asking is there code references for photocells and what is it classified as?

 

[hbiss]

Reason i ask snap switches have to be rated for 20 amp if on 20 amp breaker.

Where did you get that from?

From what i can see by code a commercial sign has to be on a dedicated 20 amp circuit.

And where did you get that from? Dedicated, maybe. But it can't EXCEED 20A.


-Hal

 

[mavrck]

Where did you get that from?

Sorry HAL 404.14 says must be used with in their ratings indicated

And where did you get that from? Dedicated, maybe. But it can't EXCEED 20A.

Sorry HAL rated at least 20 amp. 600.5a

So now that you know i can read the code book do you have anything of relevance to bring to the photocell question. If not that's fine. If i knew everything about code I sure wouldn't be on a forum asking questions.

 

[tom baker]

Your best reference on photo controls is 110.3 B. I dont recall any sections on photocontrols in the luminaire article, I will look later today.

 

[mavrck]

Thank you

 

[hbiss]

Sorry HAL 404.14 says must be used with in their ratings indicated

Within the ratings of the load, not the branch circuit.

-Hal

 

[Seven-Delta-FortyOne]

Sorry HAL 404.14 says must be used with in their ratings indicated




Sorry HAL rated at least 20 amp. 600.5a

So now that you know i can read the code book do you have anything of relevance to bring to the photocell question. If not that's fine. If i knew everything about code I sure wouldn't be on a forum asking questions.

Settle down, man.

There are some super knowledgeable folk on here, who take their personal time to give free advice to strangers.

The NEC is a complicated document, and we’ve had multiple-page threads hashing out an issue, and everyone’s understanding of it.

Don’t take it as a criticism of your knowledge.

As for your question, I don’t know, I’ll have to go read the Code book.

 

[James L]

Does 600.6(b) have any relevance here?

 

[James L]

From what i can see by code a commercial sign has to be on a dedicated 20 amp circuit

What is the purpose of the sign and where is it?
The minimum 20 amp or maximum 20 amp are for different sign purposes.

A sign at the entrance have to be on a minimum 20 amp circuit. All other signs have to be on a maximum 20 amp circuit

 

[mavrck]

What is the purpose of the sign and where is it?
The minimum 20 amp or maximum 20 amp are for different sign purposes.

A sign at the entrance have to be on a minimum 20 amp circuit. All other signs have to be on a maximum 20 amp circuit

It is going to be on the front of a church , with a entrance to the left of the sign.

 

[hbiss]

What is the purpose of the sign and where is it?
The minimum 20 amp or maximum 20 amp are for different sign purposes.

A sign at the entrance have to be on a minimum 20 amp circuit. All other signs have to be on a maximum 20 amp circuit

That's what I was referring to.

Does 600.6(b) have any relevance here?

I would agree it does.

-Hal

 

[mavrck]

My main concern is using a photocell that is rated for less then what the branch circuit protection is. (6 amp rated photocell on 20 amp circuit) But after thinking further into this is no different then supplying a contractor or individual wall pack. The PC is going to be dedicated to a sign load that only pulls 4-5 amps. So there should be no concern of over current on the PC and the branch circuit will protect against short circuit. I believe i'm over thinking the installation.

 

[mavrck]

Is electronic power supply refereeing to the sign load i'm assuming? It doesn't seem to call out the branch circuit OCPD.

 

[GoldDigger]

Sorry HAL 404.14 says must be used with in their ratings indicated




Sorry HAL rated at least 20 amp. 600.5a

So now that you know i can read the code book do you have anything of relevance to bring to the photocell question. If not that's fine. If i knew everything about code I sure wouldn't be on a forum asking questions.

There is a big difference between a switch controlling a hard wired load and a switch controlling a receptacle, even if the receptacle is intended for a specific load. If the receptacle is rated for 15A or 20A, then the switch would have to be rated support a full current load.
I have not encountered a situation where a photocell controlled a general purpose receptacle.

 

[James L]

Is electronic power supply refereeing to the sign load i'm assuming? It doesn't seem to call out the branch circuit OCPD.

I believe it is referring to the LED power supply, and saying your photocell can only be loaded to 50%

I think you need a 10 amp pc for 5 amp sign.

That just seems wise, too. Can you use the pc to control a relay?

 

[tom baker]

Again, back to 110.3 (B).
Is this PE in the branch ckt to the sign, or installed in the sign?

 

[mavrck]

Again, back to 110.3 (B).
Is this PE in the branch ckt to the sign, or installed in the sign?

in the branch circuit to the sign, it will be mounted in a WP box.