Calculating Amperage - does my calculation look correct?

[Bohemian Waxwing]

Hi all,

I wanted to make sure my power bar wasn't trying to carry more amperage than the fuse (15 amp).

The power bar is an APC PH8W 2160 joule Surge Protector, rated for a maximum amperage of 15 (but obviously I would cap it lower).

Here are my calculations - note that the power draw in Watts is always the gear's maximum draw. Calculated amps as A = Watts/Volts.

	Watts​	Voltage​	Amps​
Return pump	5​	120​	0.04​
AI Prime 16	59​	120​	0.49​
AI Nero 3	20​	120​	0.17​
Tetra heater	50​	120​	0.42​
Helios heater	30​	120​	0.25​
Bubble Magus MiniQ	2​	120​	0.02​
	166​		1.38​

 

[Bohemian Waxwing]

Also, if I pay approx. $0.08 per KwH, and the tank uses 166W at any given time, does this calculation make sense for monthly running cost:

KwH​	Dollars/kwH​	Hours/day​	Dollars/day​	Dollars/month​
0.166​	$0.08​	24​	$0.32​	$9.56​

Since the lights, powerhead and heaters only run sometimes and not at full power, I would assume the real cost to be closer to $3-4/month. The units running 24/7 are the lowest draw.

 

[Timfish]

Looks good to me.

 

[rhitee93]

Yep, right approach.

The only caveat I would say is that the "Wattage" listed by most devices is not something I would consider accurate. It'll get you in the right ballpark, but you want to make sure you leave yourself some wiggle room.

 

[C4ctus99]

Looks accurate. Just a note, for continuous duty you probably want to stay @85% of your fuse rating (12A)