Electrical: How much can I draw from a 20A circuit?

[Ejeckt]

Hopefully there's an electrician or two around that can help me with this one.

My garage/workshop has a single 20A circuit with a socket that accommodates one plug. My current max draw would be running a tablesaw or planer (1500w 230v single phase), a dust collector (same type of motor), 2 fans and 6 florescent lights. So about 440w. Total is 3440w, no? That ran fine without any trips but now my DC packed up and the only replacement I can get readily has a 3HP motor (2250w). I think the extra 750w should be fine on the circuit and I'm also thinking to replace the single wall socket to one that has space for two plugs and running the two big machines on separate 16a plugs.

Just want to know if I'll burn down my house this way I considered pulling another 20A circuit into the garage but the R2000 I was quoted for that is a bit high for something I "might" not even need.

The second alternative is to run a really long extension cord from the house to the garage whenever I'm working in there.

Thanks

 

[ScottulusMaximus]

The circuit breaker can do 4800W before it'll trip, the house wiring can handle much more than that by design so the breaker trips before the house burns down.

The plug and socket on the other hand is only rated at 15A so 3600W MAXIMUM, if you're using multi-plugs etc they will be rated for a lot less.

TLDR: running all that off one plug and adaptors is going to melt something.

 

[Sinbad]

What he said.
Also beware of inrush current (startup current) on motors

 

[azbob]

Wait, never mind that.

 

[SYNERGY]

And I wouldn't run an extension from the house either.
Bound to melt.

 

[Rickster]

I'm sure the above average joe can wire a 20 amp circuit, just open your DB and replicate one of those.

 

[Ejeckt]

Thanks guys, so the circuit can handle the load but the plug can't.

...The plug and socket on the other hand is only rated at 15A so 3600W MAXIMUM, if you're using multi-plugs etc they will be rated for a lot less.

What I meant in the latter part of my post was replacing the wall outlet with a double one, and then the dust collector would be on it's own plug. Are those wall outlets also rated at 15A like a multiplug? (One of these.) On this chart it shows the double outlet as 2x16A so I understood the outlet works differently than a multiplug, but now I'm not sure.

What about putting in another wall outlet right above or below the current one? Just doubling up the wiring?

And I wouldn't run an extension from the house either.
Bound to melt.

Well it would only be for one of the tools, probably the dust collector.

I'm sure the above average joe can wire a 20 amp circuit, just open your DB and replicate one of those.

I've thought about that but I'm very nervous of messing with electricity. I'll read up on what it takes though, I think I can use the same conduit though (breaker is in the house - garage doesn't have a circuit board)

 

[Tacet]

The wall plugs normally have their ratings at the back, so when you go and buy one look at the rating. They're not all the same. As for the extension cord - the expensive part of wiring in another 20 A circuit is probably the copper. Buying an extension cord that can handle sufficient power over the same distance will have the same problem - it won't be cheap.

 

[wetkit]

Replacing the single outlet with a double outlet would be the smart thing to do.
You could also install Gewiss plugs that is rated for higher amps, but these will cost a lot more.

How much is R2k compared to burning down the house?

 

[Pilgrim]

I agree with the advice to replace your current single plug with a double plug. Try to get one with only a single input for your current wire, otherwise make sure to buy some really thick wire as well to link the two plugs together (my wall socket behind my TV has two distinct plugs behind the faceplate, but it is really old)

Also check the size of the wire receptacle, there is nothing more frustrating than trying to force a 3mm wire into a 2.5mm hole

 

[heartbroken]

I agree with the advice to replace your current single plug with a double plug. Try to get one with only a single input for your current wire, otherwise make sure to buy some really thick wire as well to link the two plugs together (my wall socket behind my TV has two distinct plugs behind the faceplate, but it is really old)

Also check the size of the wire receptacle, there is nothing more frustrating than trying to force a 3mm wire into a 2.5mm hole

/wink wink nudge nudge

 

[ScottulusMaximus]

Thanks guys, so the circuit can handle the load but the plug can't.



What I meant in the latter part of my post was replacing the wall outlet with a double one, and then the dust collector would be on it's own plug. Are those wall outlets also rated at 15A like a multiplug? (One of these.) On this chart it shows the double outlet as 2x16A so I understood the outlet works differently than a multiplug, but now I'm not sure.

What about putting in another wall outlet right above or below the current one? Just doubling up the wiring?




Well it would only be for one of the tools, probably the dust collector.



I've thought about that but I'm very nervous of messing with electricity. I'll read up on what it takes though, I think I can use the same conduit though (breaker is in the house - garage doesn't have a circuit board)

Replacing the single socket(outlet) with a double one should be fine, just check the ratings in the shop and get a heavier duty one. By multiplug I meant a double adaptor type thing. A separate single socket will accomplish the same thing.

Don't run an extension.

If you're nervous don't fiddle with the DB board, changing the socket is easy, just switch off the breaker

 

[Sinbad]

Replacing the single socket(outlet) with a double one should be fine, just check the ratings in the shop and get a heavier duty one. By multiplug I meant a double adaptor type thing. A separate single socket will accomplish the same thing.

Don't run an extension.

If you're nervous don't fiddle with the DB board, changing the socket is easy, just switch off the breaker

Switch off the mains.
I got shocked between neutral and ground before on a circuit with the breaker turned off. Breakers don't isolate the neutral line. No idea why there was voltage but it hurt.

 

[AstroTurf]

I believe you are allowed to put a maximum of 4 plugs onto the cable. It may be a good idea to do that.

 

[ScottulusMaximus]

Switch off the mains.

+1

 

[Awesum]

Switch off the mains.
I got shocked between neutral and ground before on a circuit with the breaker turned off. Breakers don't isolate the neutral line. No idea why there was voltage but it hurt.

You should check the elevated voltage on the neutral (N to E voltage). It shouldn't exceed 25V.
Your earth might not be continuous or the N-E link at the supply is off.

 

[Sinbad]

You should check the elevated voltage on the neutral (N to E voltage). It shouldn't exceed 25V.
Your earth might not be continuous or the N-E link at the supply is off.

Wasn't my house ...

 

[Geoff.D]

Rule 1: never take anything electrical at face value.
Rule 2: Switch off the CB in the board. If you really want to be safe, cut the power completely.
Rule 3: Take a multimeter and measure L-E, N -E, L- N at the point where you want to undertake any work. These days there are some nice simple Earth Leakage tester units with visual indicators that are a very good way to make sure spurious voltages are either non existent of low enough to not be a danger.

If you are considering doing more than a double socket in the garage, Then it pays to get an electrician in to do the job properly for you with a DB board and a separate feed from the main board. Yes it will cost but in the longer run it will be money well spent. A separate socket for each major appliance is the answer and with the lights on their own CB as well.