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Block heater trips GFCI
I have the standard AC outlet (GFCI) in the engine compartment. Recently, the block heater has started to trip the GFCI breaker in the outlet. It is not the outlet because if I plug the block heater directly into a barn outlet using an extension cord, it also trips the GFCI breaker in the barn.
Does that mean my block heater element has gone bad?
There is no continuity between ground and neutral or ground and the hot wire. The heating element still seems fine (I measure 12.5 Ohm or about 1000W).
I tried to trace the wire but could not find the block heater. The wire runs down the oil line from the reservoir and then across the rear of the engine and then seems to disappear below the turbo. Anybody know where the block heater is on a late 90’s series 60?
Thanks, Gerald
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5 Replies
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You are correct as it is on the side of the block, behind the area of the turbo….
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What about continuity between the hot/neutral and the engine ground? Was shore power plugged in when you plugged the block heater in to your shop?
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Yes, shore power was plugged in both cases (using the internal outlet and using the barn outlet). Both are grounded through the barn panel.
What may be going on is that the block heater element leaks towards ground only when hot causing the GFCI to trip.
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right behind the exhaust side of the turbo (just below that red wire).
Unfortunately, it seems like Prevost built the bus around that block heater. No way to get to it from above (exhaust manifold and turbo, below (oil filters & cooler, muffler) or rear without removing cooling fan and transmission.
I measured 140 kOhm between hot and ground, so it IS leaking about 1 mA to ground. GFI trip current is supposed to be 5 mA. I’d love to take a look at that connector and measure leakage directly at the block heater but …..
Looks like we’ll be using the Webasto to preheat the engine during our upcoming trip south.
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I have had a block heater on all my coaches. The last two have had a Webasto and as a result I never used the block heater on them.
At home the last two coaches were garaged and no preheat was required. On the road however, if it was cool enough to require some heat in the engine, it was also cool enough so I wanted to use the Webasto to keep the interior comfortable, and as a side benefit the engine got heat as well.
Just a general observation, if it is still warm enough outside to be able to use the heat pumps to warm the coach interior, it is warm enough so even if the engine is cold you will not have to pre-heat it. If it is cool out and the engine has not been preheated just do not rev it up when it starts. let it idle and get the oil circulated a little for a minute or so before you go to high idle or rev it up/
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