Is a relay a load?

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realolman

Senior Member
I'd say it's both.

I'm with ptonsparky... in the circuit that supplies the coil, it's a load. With electronic circuits, and switches it's a load that you need to consider carefully.

In the switched circuit, I'd say it was like a device.
 
raider1

raider1

Senior Member
Staff member
Location
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SG-1 said:
Device, just because it uses incindental energy to control or carry electricity does not effect it's primary function.
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I agree. The definition of device was change in the 2008 NEC to clarify that a device may utilize a small portion of energy but its primary function is to control or carry electric energy.

Device. A unit of an electrical system that carries or controls electric energy as its principal function.
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Chris
 
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richwaskowitz

Senior Member
Location
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Relay a load?

Relay a load?

It depends on the context, in other words, why you are asking. From a UL508A perspective, a relay is not a load if you are trying to distinguish a control circuit from a power circuit. UL508A 2.31 defines a load as a "device external to the industrial control panel that is connected to the power circuit". Even if a relay or contactor would be external to the panel, it would still not be a load but a control device. Perhaps the relay controls something in the power circuit, but a relay is not itself a load; from this perspective. Did this help or confuse the issue????
 
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jbyrnes

Member
LarryFine said:
J, welcome to the forum! :)

Can you provide some context?
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Thanks! Sorry it took me so long to reply, i had touble finding my own post here, it is my first.

I am an electrical instructor and the question actually came from an HVAC student. He was asking in reference to the low voltage relay in his wiring schematic, and wanted to know if it was a load. I replied that imo it was a device and not a load as that is how we teach it in electrical.(A device is a peice of equipment meant to carry but not utilize power) But in HVAC it is considered a load. I asked the other instructors i worked with and everyone seemed to disagree on the definition of a load.(how much power does it have to use to be a load, and does it have to use power to accomplish a desired task?) because even wire uses a minute amount of electricity due to its resistance but no one considers it a load, a dimming switch also uses a minute amount of power to function but no one considers it a load.

I appreciate everyones input here and i believe you all basically came to the conclusion i did, that it depends on its function. If a relay falls under the jurisdiction of the nec it is a device by its definition, But as soon as you get to the electronics world it is very much so a load.
 
weressl

weressl

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Texas by the Gulf, geat crab, great shrimp
jbyrnes said:
Thanks! Sorry it took me so long to reply, i had touble finding my own post here, it is my first.

I am an electrical instructor and the question actually came from an HVAC student. He was asking in reference to the low voltage relay in his wiring schematic, and wanted to know if it was a load. I replied that imo it was a device and not a load as that is how we teach it in electrical.(A device is a peice of equipment meant to carry but not utilize power) But in HVAC it is considered a load. I asked the other instructors i worked with and everyone seemed to disagree on the definition of a load.(how much power does it have to use to be a load, and does it have to use power to accomplish a desired task?) because even wire uses a minute amount of electricity due to its resistance but no one considers it a load, a dimming switch also uses a minute amount of power to function but no one considers it a load.

I appreciate everyones input here and i believe you all basically came to the conclusion i did, that it depends on its function. If a relay falls under the jurisdiction of the nec it is a device by its definition, But as soon as you get to the electronics world it is very much so a load.
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I think it may be better defined, that from the 'power' end it is a device, and from the 'control' end it is a load.

From the power end one's concern is: how much current can it switch and from the control end how many VA load does it represent so the CPT can be sized accordingly.
 
al hildenbrand

al hildenbrand

Senior Member
Location
Minnesota
Occupation
Electrical Contractor, Electrical Consultant, Electrical Engineer
Welcome to the Forum!
jbyrnes said:
Just curious if a relay is considered a load, i know it draws power but is it a device or a load?
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It's worth noting the explanatory text from the 2008 NEC Handbook Article 100 Definition of Device:
2008 NEC Handbook
Article 100 Definitions

Device. A unit of an electrical system that carries or controls electric energy as its principal function.

Components (such as switches, circuit breakers, fuseholders, receptacles, attachment plugs, and lampholders) that distribute or control but do not consume electrical energy are considered devices. Devices that consume incidental amounts of electrical energy in the performance of carrying or controlling electricity are also considered devices. Some examples of these components include a switch with an internal pilot light, a GFCI receptacle, and even a magnetic contactor.
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This definition applies within the Premises Wiring (System) (another Article 100 Definition). Also, note the last sentence of the definition of Premises Wiring (System) describes that which, though connected, is not part of the Premises Wiring (System).
 
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
To restate what other have said:

From the perspective of the controlling circuitry, it is a load.

From the perspective of the load it controls, it is a device.
 
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