Simple Ampacity Calculation Question

Student studying for electrical calculations final and need help with the following question:

Given 2 Electric ranges sized at 5500W, 2 ovens sized at 6500W and 2 broilers sized at 3500W, all to be installed in a single family residential dwelling, calculate the ampacity of this circuit.

I can calculate the demand load for these, but am super at how to figure the ampacity. Thanks in advance.
 

Besoeker

Senior Member
Location
UK
Student studying for electrical calculations final and need help with the following question:

Given 2 Electric ranges sized at 5500W, 2 ovens sized at 6500W and 2 broilers sized at 3500W, all to be installed in a single family residential dwelling, calculate the ampacity of this circuit.

I can calculate the demand load for these, but am super at how to figure the ampacity. Thanks in advance.
Do you know what the voltage is? You need that for the calculation.
 

Little Bill

Moderator
Staff member
Location
Tennessee NEC:2017
Occupation
Electrician
Do you know what the voltage is? You need that for the calculation.
The OP's question involves using a table (220.55) All the ratings are in kW. It's true he needs to know the voltage but first he must determine the kW.

OP, look at the Table 220.55 and see which part applies to the question. If you need help, post back with your questions.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
Student studying for electrical calculations final and need help with the following question:

Given 2 Electric ranges sized at 5500W, 2 ovens sized at 6500W and 2 broilers sized at 3500W, all to be installed in a single family residential dwelling, calculate the ampacity of this circuit.

I can calculate the demand load for these, but am super at how to figure the ampacity. Thanks in advance.
I am curious as to what a broiler is--Isn't that an oven? Also if you did calculate the demand then just divide by 240V as that is the usual voltage for a residence
 

JFletcher

Senior Member
Location
Williamsburg, VA
"calculate the ampacity of this circuit."

Huh? :?

I could see calculating demand for those appliances but not a circuit ampacity as they would be on different circuits (plural).
 

Besoeker

Senior Member
Location
UK
I am curious as to what a broiler is--Isn't that an oven?
It's what we in UK would call a grill. It's an oven that heats from the top - the heating element is above the food. My dear wife, an American, has just confirmed that.
Maybe you don't do the cooking in your house...................:p

With the possible caveat for fan assisted ovens the loads are resistive which keeps the calculation simple. And I take your point about the 240V being the norm but unless it is given in the question I'd be inclined to suggest that the student adds a note to say that's what he used for the calculation. Just me crossing the Is and dotting the Ts............:)
 

Strathead

Senior Member
Simplest answer?

Simplest answer?

We are supposed to be trying to answer more simply correct? Wouldn't we merely instruct the OP that the demand load IS the ampacity? He already indicated he knows how to figure it out. What am I missing?
 

kwired

Electron manager
Location
NE Nebraska
It's what we in UK would call a grill. It's an oven that heats from the top - the heating element is above the food. My dear wife, an American, has just confirmed that.
Maybe you don't do the cooking in your house...................:p

With the possible caveat for fan assisted ovens the loads are resistive which keeps the calculation simple. And I take your point about the 240V being the norm but unless it is given in the question I'd be inclined to suggest that the student adds a note to say that's what he used for the calculation. Just me crossing the Is and dotting the Ts............:)
Since you are not an NEC user we will cut you some slack this time.:)

The demand table is in kW, demand load being asked for would still be in kW.

You will need to know voltage/number of phases if you are going to convert this to how many amps will the circuit draw.
 

Smart $

Esteemed Member
Location
Ohio
We are supposed to be trying to answer more simply correct? Wouldn't we merely instruct the OP that the demand load IS the ampacity? He already indicated he knows how to figure it out. What am I missing?
You are not missing anything... :p
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Electrical Contractor
It's what we in UK would call a grill. It's an oven that heats from the top - the heating element is above the food. My dear wife, an American, has just confirmed that.
Maybe you don't do the cooking in your house...................:p

With the possible caveat for fan assisted ovens the loads are resistive which keeps the calculation simple. And I take your point about the 240V being the norm but unless it is given in the question I'd be inclined to suggest that the student adds a note to say that's what he used for the calculation. Just me crossing the Is and dotting the Ts............:)
Yes but every oven I have seen has a broiler... I have never seen a unit that was just a broiler
 

JFletcher

Senior Member
Location
Williamsburg, VA
I am curious as to what a broiler is--Isn't that an oven? Also if you did calculate the demand then just divide by 240V as that is the usual voltage for a residence
Kinda a toaster and portable oven. Cord and plug

(eta: removed busted link)

I'd call it a toaster tho I think most people think the pop-up kind now. or maybe I'm wrong again. :p
 

Besoeker

Senior Member
Location
UK
Since you are not an NEC user we will cut you some slack this time.:)

The demand table is in kW, demand load being asked for would still be in kW.

You will need to know voltage/number of phases if you are going to convert this to how many amps will the circuit draw.
For what am I being cut slack?
We use kW too............
 

Besoeker

Senior Member
Location
UK
Yes but every oven I have seen has a broiler... I have never seen a unit that was just a broiler
Well, its a question for a student and we have seen that they quite often relate to circumstances and circuit arrangements you wouldn't see in real life.
 

Barbqranch

Senior Member
Location
Arcata, CA
Occupation
Plant maintenance electrician
Salamander

Salamander

There is a professional broiler often called a salamander that mounts up on the wall. It is faster to use and doesn't take up oven space. Restaurant use, mainly.
 

JFletcher

Senior Member
Location
Williamsburg, VA
There is a common appliance like that, called a toaster oven. Is that what it is, or something more substantial?
No idea if toaster oven = broiler. I'd consider them the same tho. I've never seen a 3500W one; all residential ones would be cord and plug and at best have a 5-20p on them at ~2kw max, realistically a 120V model at 1500W with a 5-15p.

I dont think Ive ever seen a hardwired toaster oven/broiler. The OPs question is so terribly worded that discussing what is a broiler is mostly moot anyway. I'd look in 220.55, do the calcs, and hope the answer I arrived at was on the test. As far as "real world", all 6 of these appliances would be on individual circuits of differing ampacities.
 
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