Avoiding "overloading" a house circuit?

[cheeseandachallenge]

I'm shooting in a house in a couple of weeks. I'll be running a pretty minimal set up with 1200w in lights and a 1000w smoke machine. That said, I don't know a heap about circuits (despite starting my degree studying electrical engineering, my practical skills are dire) and this is a student flat. How do I make sure I can run all this without blowing the circuit - what do I need to check, etc? And if it is too much for the circuit, am I out of luck, or can I use transformers (or something)?

Cheers.

 

[Zensteve]

1) Locate fusebox - you'll need to immediately know where to go, if you do blow anything. Also, this is where you'll likely find a diagramme of each of the circuits, which helps you decide how many amps can be used from any given area. Also, you'll see if the breaker box uses resettable breakers or actual old-school fuses - in which case, bring spares.

2) When choosing set of outlets on the same circuit, the fusebox will list how many amps that circuit has. You can figure out the amps required by each your lights and other electric devices easily enough (ask Google; watts to amps/voltage). That way you can arrange to have appropriate lighting gear added up on a single circuit.

3) Bring lots of extension cords, so you can spread the load out among the various rooms, if needed.

4) Your fogger draws a lot less when warming up & on standby. Make sure there's spare overhead for when it needs to pump it all out, while simaltaneously heating up more fluid from the reservoir.

That's it, really. Obviously, take notes on what the amps are for each piece of gear so you won't have to do it again. Oh, and if a fuse blows - never use the coin replacement. Fuses blow for reason.

 

[Zensteve]

if it is too much for the circuit, am I out of luck, or can I use transformers (or something)?

You should be able to spread the load within even a small apartment, given that your equipment list seems pretty small. If you can't, then ask a neighbour if you can run extensions. Maybe they'll say yes. Maybe they'll say no. You might also have the option of running actual house power; an outlet used for a common laundry room, or for powering lawn sprinkler timers, or whatever.

 

[cheeseandachallenge]

Alrighty, cheers Zen. Annoyingly it seems the fusebox doesn't have diagrams, it's just numbered. Is there a way to figure out how the house is divided up (if that even makes sense?) - and if not, would it just be safest to run a number of extension chords from various rooms?

Good point on the fogger. I'm not really using it too much, just to diffuse the light a bit and soften things up in a subtle way (e.g. in the first example here http://www.hurlbutvisuals.com/blog/2012/05/diffusion-for-the-digital-age/) so I should be able to run it fairly sporadically with the lights off, which'll make things easier.

 

[jax_rox]

Assuming the fuse box is running with RCDs:

Turn of all the circuits. Then turn on one. Take a small light, or even a phone charger and plug it into every socket in the house. Label the ones that you can draw power from with a colour (say, blue). Then label that circuit on the fuse box with blue.

You should have a circuit that runs lights, one that runs kitchen appliances/rangehood etc. and then 2-4 for house power. You then know when you're drawing power that you have (say) 2x 1ks on the blue circuit, so you should use the red circuit for anything bigger than 200-400w.

Generally, most household circuits will give you a max of 2.4k over the circuit (assuming 240v power).

If using larger units (for example, running a 2.5k HMI on one circuit), you need to account for shorter cable runs to prevent line loss, and also generally much higher grade power extensions.

If you can afford it, run your craft table/unit on one circuit dedicated solely to them, as you never know when someone is going to run the coffee machine, or microwave, or kettle, or even iron to iron a costume and suddenly half your lights blow.

 

[cheeseandachallenge]

Good idea Jax. I believe New Zealand is pretty similar to Aus, so most of what you said should be applicable. To make sure I understand correctly:

1) Using process of elimination label each circuit and corresponding sockets
2) 1 circuit will run the lights (I presume you mean household lights, meaning I don't need to give it much thought once identified?), one will run kitchen/rangehood, then a few more will be household circuits (use these for my lights and fogger?)
3) Generally, each household circuit can run about 2400w. To make sure, is there a way to work the circuit max load?

Good advice on the last point. I have a pretty small team for this shoot, so should be manageable

Apologies for what may be very basic questions - I'm not an amazingly practical person when it comes to stuff like this.

 

[jax_rox]

That's pretty much it!

I believe even the physical electrical sockets are identical in New Zealand to those in Australia, so I believe you'll find it's a very similar situation.

Each circuit should have the max number of amps labelled on it at the fuse box. Generally, it's 10 amps (or 2.4k), though newer buildings will have some 15amp or even 20 amps circuits. To get the number of amps, divide the wattage by the voltage. For example, a 1k Fresnel draws a bit over 4 amps (1000watts / 240volts). If you have three of these, you know you could put all three onto a 15 amp circuit without hassle. If you only have a 10 amp circuit, you could only have two on it, and not much else.

Failing that, you know you've maxed out the circuit when it trips and everything turns off!

 

[directorik]

The "non-electrician" method I used for many years was to plug
everything onto a bunch of power-strips. It will break before the
house circuit does.

 

[cheeseandachallenge]

Thank you all! Comprehendable and very useful advice!

 

[cheeseandachallenge]

So I finally went to do this today. And there is a slightly odd situation.. There are two flats using the same circuit box (there are also only 5 circuits). This is the circuit box:

So I talked to the upstairs flat (Flat 2), and asked them to tell me when their power went on/off, to figure out which circuits correspond to theirs. Circuits B & C appeared to be theirs (they later came down to tell me that their oven wasn't working - so circuit e also powers their oven). Which left me with circuits A & D for the downstairs flat (Flat 1 - where we are shooting) - which seemed odd, given it was the larger house.

Anyway, long story short, it seems even with both circuits A & D switched off, everything in Flat 1 was still running... So I can't really figure out what circuits A&D are powering (I figure one could be hot water) - and that leaves me with the problem of having to guess which sockets I can use.

Any suggestions? Or given my relatively low power requirements and that it is only a breaker box as opposed to a fuse box, should I just go for it and if the lights go out, move things around (doesn't seem like a great option)? I'll also obviously tell the upstairs flat what we're doing.

 

[jax_rox]

A & D are 20Amp circuits, whereas the upstairs power circuits are 8-amp circuits. I would imagine these are powering something else, given the information you've provided. Perhaps hot water, rangehoods - sometimes houses have seperate circuits for a fridge or other appliances.

It makes it tough - are you sure there's no other circuit breakers/fuse box around?

Your power draw isn't huge - you'll probably fit it on one circuit. If you can't figure it out, put everything on power boards with circuit breakers and hope for the best. If you're not having to replace fuses, then flipping a switch isn't too big a deal (thogh, of course you need to find where those circuit breakers are anyway if you do trip one).

 

[cheeseandachallenge]

I checked to see if all the rangehoods were still working with A & D, and they were. So I think the landlord has done an odd DIY job (it's a 4 bedroom house split into two flats, there are a few other weird things going on).

Breakers are just above, out of frame, so it won't be a big deal. Just a bit of a pain.

But thanks for the help up until now, useful to know for future situations.