400 watts @110volts = ? amps @240 Volts. (1 Viewer)

Free Member
Title says it all (hopefully!)

Basically, there is a HOTROD available for the Atwood/Suburban water heaters which uses 400 watts at 110Volts.
What I'd like to know is, when I'm on a 240Volt hook up, how many of my precious 10amps is that gonna use?

p.s Being sad (and bored at work!) I'd appreciate seeing the relevant formulae.
I tried Google and confused the hell out of myself!

Ta:thumb:

scotjimland

LIFE MEMBER
Hi

400 watt is the power, dived by the voltage for the amps..

ie watts = Volts x Amps

Posted via Mobile Device

OP
OP

Free Member
Hi
400 watt is the power, dived by the voltage for the amps..
ie watts = Volts x Amps
Posted via Mobile Device

Ah! Thanks Jim. I thought it would be more complicated than that.oh:

scotjimland

LIFE MEMBER
Hi
Don't worry, someone will be along soon to complicate it

how many motorhomers to change a light bulb ?
Posted via Mobile Device

American Dream

Free Member
[Hi
Don't worry, someone will be along soon to complicate it

how many motorhomers to change a light bulb ?
/QUOTE]

Meeeeeeee

The calculation is correct but.....Won't doubling the voltage to it blow the element?

Just a thought.

It's like applying 24v to a 12v light bulb.I bought a site transformer to bring the voltage down for just that reason.

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OP
OP

Free Member
[Hi
The calculation is correct but.....Won't doubling the voltage to it blow the element?
It's like applying 24v to a 12v light bulb.I bought a site transformer to bring the voltage down for just that reason.

If I was doing that, you'd be right.
But I wont be. The element will be run via a 110volt step down tranny.
All I needed to know was how much of my precious 240 that would equate to.
Fulltiming on a 10amp supply can be made sooooooo much easier if you take the time to learn the power consumptions of your equipment so that you get to know what you can and cant run at the same time.:thumb:

American Dream

Free Member
If I was doing that, you'd be right.
But I wont be. The element will be run via a 110volt step down tranny.
All I needed to know was how much of my precious 240 that would equate to.
Fulltiming on a 10amp supply can be made sooooooo much easier if you take the time to learn the power consumptions of your equipment so that you get to know what you can and cant run at the same time.:thumb:

Aaah Right,

I'm using a step-down in much the same way although not continuously.:thumb:

S

stagman

Deleted User
Title says it all (hopefully!)

Basically, there is a HOTROD available for the Atwood/Suburban water heaters which uses 400 watts at 110Volts.
What I'd like to know is, when I'm on a 240Volt hook up, how many of my precious 10amps is that gonna use?

p.s Being sad (and bored at work!) I'd appreciate seeing the relevant formulae.
I tried Google and confused the hell out of myself!

Ta:thumb:

You probabally will need a 240v to 110v transformer that can handle at least 6amp on the secondary side i.e the 110v side :thumb:

PeteH

Free Member
Pedantry

Hi

400w @ 110v = 3.6?????? amps 400w @ 220V = 1.81???amps

400w @ 240V = 1.66??amps

A 2:1 step transformer with primary pd 240vAC will produce 120vAC (ignoring losses) Good quality transformers will have several "tappings" allowing selection of an output voltage nearest to your requirement.

The "hot-rod" will cope with just about anything from 100 to 130v.

Don`t forget to specify the Frequency rating, its not particularly critical BUT a transformer is designed for use on a certain frequency and "Off Frequency" can sometimes produce an anoying "humm" or "buzz". "overspec" can be expensive and a 5 to 6 amp rating on the secondary side, as suggested, will be more than adequate, you MAY even have one on board IF you are still using the American spec; Microwave etc? If so check its rating as it may be capable of taking the hot-rod as well?

Pete

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