Extension cords - risks with appliances like clothes drier and heater

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#2557389 5-Sep-2020 11:07

Almost every post on this thread is bad. I lost count how many times someone has repeated the same stupid suggestion that the lead be changed.

Please don't do any of this BS

You're not on Atlantis anymore, Duncan Idaho.

timmmay

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#2557400 5-Sep-2020 11:36

I don't think cutting a cord is a great idea.

Yes there are risks using extension cords for high current devices, but we have to use them for appliances in practice. We buy good quality cords, check them every few months, make sure they're plugged in properly, and we've not yet had a problem. We do things like avoid running too much current through a single outlet, keep cords uncoiled, and try to avoid them getting hot. Not much else we can do really. Getting new sockets in is difficult and disruptive, and somewhat expensive to get repaired - last time they cut holes all through a wall and it had to be plastered closed, painted, etc.

larknz

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#2557414 5-Sep-2020 12:29

There is nothing wrong with cutting an extension cord to shorten it, as long as you use good quality replacement fittings on the ends and you know what you are doing. Electricians make up extension cords regularly.

Bung

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#2557417 5-Sep-2020 12:41

MadEngineer:
Almost every post on this thread is bad. I lost count how many times someone has repeated the same stupid suggestion that the lead be changed.

Please don't do any of this BS

You sound like the sort of engineer responsible for the American National Electrical Code that mandated 4ft cords for dishwashers yet allowed the socket to be mounted 6ft away from the dishwasher.

snnet

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#2557672 5-Sep-2020 20:54

Bung:
Were there any more details of this incident. A "fire caused by an extension cord" that just happens to be beside a hot water radiator. Was it actually the fact that some idiot had draped the cord over a heater that that caused the problem?

it says it was caused by the washing machine using an extension cord - those radiators don't get so hot that they melt leads and cause them to combust

I've also seen similar at jobs, but in particular when they were used with tumble dryers. Just guessing but this washing machine probably had a heating element for hot water washes to bring the load up

timmmay

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#2557676 5-Sep-2020 21:03

Our new F&P front loader has an element to heat water. We're careful that we don't overload the socket.

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SomeoneSomewhere

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#2557680 5-Sep-2020 21:23

snnet:

Bung:
Were there any more details of this incident. A "fire caused by an extension cord" that just happens to be beside a hot water radiator. Was it actually the fact that some idiot had draped the cord over a heater that that caused the problem?

it says it was caused by the washing machine using an extension cord - those radiators don't get so hot that they melt leads and cause them to combust

I've also seen similar at jobs, but in particular when they were used with tumble dryers. Just guessing but this washing machine probably had a heating element for hot water washes to bring the load up

They get pretty close. Hydronic systems often target 60C for supply water. Most flex is rated for 75C, but is sized based on 25C ambient and a cable temperature of 60C (see table 16 of 3008.1.2), so a temperature rise of 35C at full load (and that temperature rise will be higher due to the higher resistance at high temperatures).

If you leave that flex fully loaded on a hot radiator it's going to get a lot hotter than rated.

snnet

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#2557705 6-Sep-2020 07:41

SomeoneSomewhere:

They get pretty close. Hydronic systems often target 60C for supply water. Most flex is rated for 75C, but is sized based on 25C ambient and a cable temperature of 60C (see table 16 of 3008.1.2), so a temperature rise of 35C at full load (and that temperature rise will be higher due to the higher resistance at high temperatures).

If you leave that flex fully loaded on a hot radiator it's going to get a lot hotter than rated.

My point was that having it on a heavy load appliance its going to get hot anyway regardless of being on a radiator - and the water radiators I've been around don't physically get to a temperature like 60C, would be unsafe for kids, pets, infirm etc

MadEngineer

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#2558019 6-Sep-2020 18:26

Bung:
MadEngineer:

Almost every post on this thread is bad. I lost count how many times someone has repeated the same stupid suggestion that the lead be changed.

Please don't do any of this BS

You sound like the sort of engineer responsible for the American National Electrical Code that mandated 4ft cords for dishwashers yet allowed the socket to be mounted 6ft away from the dishwasher.

That's pretty mad. I approve.

You're not on Atlantis anymore, Duncan Idaho.

timmmay

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#2560020 8-Sep-2020 06:09

I've been paying more attention to my high current appliances the past few days, considering extension cords. For example, I have a heater on a timer that has a short extension cord that runs at for my free hour of power, and has done for a couple of years with no issues. The cord stays cool, but I discovered the plug into the wall gets up to 44 degrees which is slightly too hot to touch for very long, and the end near the heater reaches about 30 degrees. I have a second heater, an oil heater, which goes into a separate plug on a separate extension cord, that doesn't get hot at all.

Are there extension cords that are better than others? Does a 1.5mm conductor help at all with this? Do I need a generally better quality cord? Or are the only solutions to turn the heating down / not use extension cords? I imagine the same thing will happen when I plug the heater directly into the wall, which I'll try later.

Now I'm working from home most of the time I'm considering getting a heat pump put into my office as that would have its own dedicated wiring back to the mains board and eliminate this problem altogether, but it would take a while to do that. There's not really any payback in it, the cost of power for a small 4 x 2m office isn't high, the only reason I'm really considering it is if it gets really hot in summer.

Bung

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#2560052 8-Sep-2020 08:44

How well does the wall socket retain the plug? Low contact pressure will lead to overheating. Have you tried running the heater from another outlet? If a socket feels loose you should replace it.

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timmmay

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#2560057 8-Sep-2020 08:49

Bung: How well does the wall socket retain the plug? Low contact pressure will lead to overheating. Have you tried running the heater from another outlet? If a socket feels loose you should replace it.

Plug and wall socket are solid. Both the plug and wall socket get warm, which makes sense as they're touching.

SomeoneSomewhere

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#2560451 8-Sep-2020 17:45

Generally, a plug or socket means a bad connection in that plug or socket, or the contacts themselves.

If you pull the plug out, is one of the pins noticeably warmer than the others?

This is generally going to be the socket, not the cord, but there are exceptions.

timmmay

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#2560492 8-Sep-2020 19:45

SomeoneSomewhere:

Generally, a plug or socket means a bad connection in that plug or socket, or the contacts themselves.

If you pull the plug out, is one of the pins noticeably warmer than the others?

This is generally going to be the socket, not the cord, but there are exceptions.

I think you're saying that if a plug or socket gets hot it's a bad connection, and if one pin gets hotter than the others it could be the socket. I'll keep an eye out thanks.

larknz

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#2560502 8-Sep-2020 20:31

It could also be a loose connection in the plug

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