Watt meter or similar? Help please

Zulu

I'm doing a home project converting a garage into a workshop.

The builders have power there currently. There's a 20amp switch on the MCB in the house for the garage, and a cable underground to the garage feeding two plugs and a light.

I homebrew, and when running a boil I've two elements boiling 50ltrs of water. This hasn't been an issue to date, but I'm concerned that the current I'm drawing will melt the wire as I've heard the the cable will only handle so many watts before overheating and melting.

Is there a "watt meter" or similar that I can have fitted in the garage the will warn me?
I can see on Amazon there are ones the you plug in but I'm not so sure and would like something that's wired directly (if possible).

Any ideas folks please?
Thanks

Cerco

I would suggest you forget about the wattmeter and calculate your power requirements.
You need to start by identifying the wattage of both elements. Then add any additional load in the workshop.
If you give those details and of the cable sizing then one of the electricians on here might assist.
I think your plan of measuring watts to prevent a cable overload is dangerous.
You need to know the loading and the load capacity of your installation before powering on.
If in doubt get an electrician in. The last thing you want is a cable overheating and causing a fire.

Leftyflip

Absolutely look at the total load requirements first.

What wattage are your boilers and what else are you running?

Watts are calculated by multiplying the amps by the volts.
So a heater element that draws ten amps would be 2300W, or 2.3kW.

You'd also want to be sure that the cable feeding the shed is of an adequate size.
This would depend on the length of the run and the installation method.

Zulu

Cheers folks,
I'll check the boilers but as an estimate its 2 kettle elements. Typically I use 1 for the most of it, and then the second element for the last 15/20 mins. This hasnt been an issue to date.

Over the past two years I've been running a pc out there with a freezer. On occasion (once a week for 2/3hours) I run the boil. And an electrical patio heater (1500W). All good.

Now I'm making it a "warmer" room (insulating). Usage will remain the same, but in the winter I will probably add an electric (low wattage) heater. Now a heater will be used more frequently and for longer than a weekly boil, hence the concern. I suspect it'll be fine but it'd be nice to see at a glance if I was approaching a limit.

Zulu

So just thinking, load would be:
Summer -
2 pc's. 2 monitors. A freezer. 8 led spot lights. A stereo. Occasionally a power tool (jigsaw, belt sander, etc..). Once a week, a boil.

Winter -
2 pc's. 2 monitors. A freezer. 8 led spot lights. A stereo. A rad (watt to be determined will look for as low as possible).
Occasionally a power tool (jigsaw, belt sander, etc..).
Once a week, a boil.

Need to do some maths.....

autumnalcore

1500w heater plus two kettle elements plus ancilliaries definitely sounds like it should be more than 20A unless you have a significant voltage drop because the cable i undersized for the mcb/run or they are not kettle elements and somekind of low wattage things.

Zulu

Managed to get hold of the electrician who was involved in building the house. He advised that the cable running out to the garage is specc'ed for 28 Amps. So thats great news.
I'm reckoning we're getting about 230V from the mains, and it's on a 20 Amp breaker on the MCB, so I should be able to draw 4.6kW without tripping and that wont be getting near to melting the cable.

With regards to the maths. I wont run the boil and the heating at the same time - which is fine, when I'm boiling I've windows and doors etc open.

Thinking PCs, monitors etc are 1kW tops. Rad upto 2.5kW gives me 3.5kW. This leaves 1kW (ample room) for running any tools.
If I'm running the boil it would be 1kW for PC's and all else off - leaving 3.5kW for the boiler. But I'm going to run one element from the kitchen for safety. So I think that will be all kosher.

...speaking of rads. The room is 2.7m wide, 5.7m long and 2.6m height (so 40m3). Anyone recommend an electric rad for heating that size? (preferably thats not a bazillion watts)

2011

Zulu wrote: »

I homebrew, and when running a boil I've two elements boiling 50ltrs of water. This hasn't been an issue to date, but I'm concerned that the current I'm drawing will melt the wire as I've heard the the cable will only handle so many watts before overheating and melting.

This is why cables are protected by over current protection devices such as fuses or MCBs. If correctly installed the fuse will blow or the MCB will trip before the cable suffers any damage. This of course assumes that it was all installed correctly in the first place which is why it is best to employ the services of a qualified electrician.

So as has been advised forget about using a watt meter to protect the cable

Zulu

2011 wrote: »

So as has been advised forget about using a watt meter to protect the cable

Duly noted and forgotten about


Fair play lads; solid advice!




...now anyone any experience of underfloor electric heating? :eek: